SPRAY-DRIED ANIMAL PLASMA IN THE DIET OF WEANLING PIGLETS: INFLUENCE ON GROWTH PERFORMANCE AND UNDERLYING MECHANISMS

GESPROEIDROOGD BLOEDPLASMA IN VOEDERS VOOR GESPEENDE BIGGEN: INVLOED OP GROEI EN ACHTERLIGGENDE MECHANISMEN

(met een samenvatting in het Nederlands)

Proefschrift

ter verkrijging van de graad van doctor aan de Universiteit te Utrecht,

op gezag van de Rector Magnificus, Prof. Dr. W.H. Gispen,

ingevolge het besluit van het College voor promoties in het openbaar te verdedigen

op donderdag 8 november 2001 des namiddags te 4.15 uur

door

Xxxxxx Xxx xxx Xxxx

geboren op 18 december 1960 te Emmen

Promotor: Prof. Dr. A.C. Beynen Co-promotoren: Dr. M.J.A. Nabuurs

Dr. T.A. Niewold

De volgende bedrijven wil ik bedanken voor hun financiële bijdrage aan deze promotie:

Cehave-Landbouwbelang Voeders BV CCL-Nutricontrol BV

Harimex BV APC Europe SA Rendac BV

Nutrifeed Veghel, business unit van Campina

Omslagontwerp en druk: Bek grafische producties, Veghel Illustratie omslag en pag. 73: Xxxxx xxx Xxxx-de Jong Fotografie pag. 105: Xxxx Xxxxxxx

ISBN 90-9015142-7

voor Tertske voor Ab

Contents

Chapter 1

Introduction 1

Chapter 2

Growth performance of weanling pigs fed spray-dried animal plasma: a review 5

Chapter 3

Zootechnical aspects 27

Chapter 3.1

Growth performance and health status in weanling piglets fed spray-dried porcine plasma under typical Northern European conditions 29

Chapter 3.2

The influence of diet composition and an anti microbial growth promoter on the growth response of weaned piglets to spray dried animal plasma 43

Chapter 3.3

Pre- and postweaning performance of piglets fed pre-weaning diets containing either spray-dried porcine plasma, whey protein concentrate or whey powder 61

Chapter 4

Small intestinal morphology and function 73

Chapter 4.1

Small intestinal morphology in weaned piglets fed a diet containing spray-dried porcine plasma75 Chapter 4.2

Small intestinal morphology and disaccharidase activities in early-weaned piglets fed a diet containing spray-dried porcine plasma 91

Chapter 5

Influence on intestinal microflora 105

Chapter 5.1

Effect of spray-dried porcine plasma on intestinal microflora as measured in vitro and in weanling piglets 107

Chapter 5.2

The effect of dietary spray-dried porcine plasma on clinical response in weaned piglets challenged with a pathogenic Escherichia coli 117

Chapter 6

General discussion 135

Summary 147

Samenvatting 153

Dankwoord 159

Curriculum vitae 161

CHAPTER 1

Introduction

Spray-dried animal plasma (SDAP) is a by-product of slaughter plants. The plasma obtained from slaughtered pigs or ruminants is spray-dried and used for the production of both human foodstuffs and animal feeds (Howell and Xxxxxx 0000, Xxxxxx 1990). It has been demonstrated in many experiments that SDAP in weaning piglets’ diets can have considerable positive effects on piglets’ growth performance. In a meta analysis, Xxx Xxxx et al. (2001) calculated from 68 comparisons between SDAP containing diets and control diets that the SDAP- induced change in average daily gain (ADG) and average daily feed intake (ADFI) in the first two weeks after weaning was +26.8 % and +24.5 %, respectively. There are no other feed ingredients or additives, that have such large effects. Two experiments demonstrated that dietary SDAP can reduce post-weaning diarrhoea (Gatnau 1990, Van der Peet-Xxxxxxxxx and Binnendijk 1995). Moreover, there are indications that the beneficial effect of dietary SDAP is much more pronounced under conditions with a high pressure of pathogens as compared to conditions with optimal hygiene (Xxxxxx and Xxxxxxxx 1995). In addition, the positive effect of SDAP on piglets’ post weaning ADFI and ADG is more pronounced in piglets that have a low baseline value of these parameters in comparison to piglets with a higher base line growth performance (Van Dijk et al. 2001). Possibly, there are interactions between infection pressure, piglet growth performance and the effect of dietary SDAP.

There are limitations to the use of SDAP as an ingredient in piglets’ diets. First, its relatively high price makes it less attractive for use than other protein sources like fishmeal or whey powder. Secondly, the use of SDAP originating from slaughter animals that have not been approved at ante and post mortem veterinary inspection can spread certain diseases like Classical and African Swine Fever and

Foot and Mouth disease (Xxxx and Sellers 1989, Van Oirschot and Terpstra 1989, Xxxxxxxxx 1989, Horst et al. 1997).

Given the limitations to the use of SDAP as a feed ingredient, it is important to unravel its mode of action. By getting insight in the mode of action, inclusion of SDAP in piglets diets can possibly be reduced to lower levels, e.g. by specific processing. Moreover, bioactive components responsible for the positive effects of SDAP may be identified and then isolated from other raw materials that are less expensive or that are not associated with the spread of diseases.

Another advantage of the identification of bioactive components from SDAP is that they may be used in human health-care, especially in the prevention of diarrhoea in neonates or in other categories of humans that are susceptible to diarrhoea. Research with piglets is then justified as these animals are considered to be a good model for humans as to the intestinal structure and function (Xxxxxxx et al. 1992).

To study the mode of action of SDAP, its possible intestinal flora modulating properties or its effects on the structure and function of the intestinal mucosa should be considered. Another means to get insight into the mode of action and to optimise its application is to investigate its use under conditions that have not been described before, i.e. under typical European conditions and in diets without anti microbial growth promoters (AMGP). Moreover, SDAP could be considered as an alternative for AMGP, that may be banned in the near future (Health Council 1998).

Therefore, the scope of the present thesis was as follows.

• To assess the effect of dietary SDAP in weaned piglets under typical European conditions.

• To investigate the interaction between dietary SDAP and complexity of the diet in weaned piglets.

• To investigate the interaction between SDAP and the use of AMGP in weaned piglets’ diets.

• To investigate the effect of SDAP in diets for suckling piglets (creep feeds).

• To measure the effect of dietary SDAP in weaned piglets on small intestinal villus length, crypt depth, mitotic activity and brush border enzyme activity.

• To measure the effect of SDAP on the small intestinal microflora of weaned piglets.

• To investigate the effect of dietary SDAP in weaned piglets that are challenged by a pathogenic E. coli.

Introduction 3

References

Xxxxxx, R.D., Xxxxxxxx, G.L., 1995. The impact of environment and antimicrobial agents on the growth response of early weaned pigs to spray-dried porcine plasma. J. Anim. Sci. 73: 2532-2539.

Xxxxxx, X., 0000. Spray dried porcine plasma as a source of protein and immunoglubulins for weanling pigs. M.S. Thesis, Iowa State University.

Health Council. 1998. Commission antimicrobial growth promoters. Publication number 1998/15. Rijswijk, The Netherlands.

Xxxxx, X.X., Xxxxxx, R.B.M., Xxxxxxxxxx, A.A., 1997. Risks and economic consequences of introducing classical swine fever into the Netherlands by feeding swill to swine. Rev. Sci. Tech. Off. Int. Epiz. 16: 207-214.

Xxxxxx, X.X., Xxxxxx, R.A., 1983. Functional aspects of blood plasma proteins. I. Separation and characterisation. J. Food. Technol. 18: 747-762.

Xxxx, X.X., Xxxxxxx, R.F., 1989. Foot and mouth disease virus. In: Xxxxxxxx, M.B. (Ed.), Virus infections of porcines. Elsevier Science Publishers, Amsterdam, pp. 251-258.

Xxxxxxx, P.J., Xxxxxxx, M.J., Cranwell, P.D., Xxxxx, W.C., Xxxxxxx, X., 1992. The piglet as a model for studying aspects of digestion and absorption in milk-fed human infants. In: Xxxxxxxxxx, X.X. (Ed.), Nutritional triggers for health and in disease. Karger, Basel, pp 40-113.

Van der Peet-Xxxxxxxxx, C.M.C., Xxxxxxxxxx, G.P., 1995. The effect of spray-dried porcine plasma in diets with different protein sources on the performance of weanling piglets. Report P1.137. Praktijkonderzoek varkenshouderij, Rosmalen, The Netherlands.

Xxx Xxxx, A.J., Xxxxxx, X., Xxxxxxx, M.J.A., Xxxxxx, R.J.C.F., Xxxxxx, A.C., 2001. Growth performance of weanling pigs fed spray-dried animal plasma: a review. Livest. Prod. Sci. 68: 263-274.

Van Oirschot, J.T., Xxxxxxxx, X., 1989. Hog cholera virus. In: Xxxxxxxx, M.B. (Ed.), Virus infections of porcines. Elsevier Science Publishers, Amsterdam, pp. 113-131.

Xxxxxxxxx, X.X., 1989. African swine fever virus. In: Xxxxxxxx, M.B. (Ed.), Virus infections of porcines. Elsevier Science Publishers, Amsterdam, pp. 17-37.

CHAPTER 2

Growth performance of weanling pigs fed spray-dried animal plasma: a review

X.X. xxx Xxxxx, X. Evertsb, M.J.A. Nabuursc, R.J.C.F. Margrya, A.C. Beynenb

a Co-operative Central Laboratory “CCL-Nutricontrol” of Cehave Landbouwbelang, X.X. Xxx 000, 0000 XX Xxxxxx, Xxx Xxxxxxxxxxx

b Department of Nutrition, Utrecht University, Faculty of Veterinary Medicine,

P.O. Box 80152, 3508 TD Utrecht, The Netherlands

c Institute for Animal Science and Health ID-Lelystad, X.X. Xxx 00, 0000 XX Xxxxxxxx, Xxx Xxxxxxxxxxx

Published in Livestock Production Science, 2001; 68: 263-274

Abstract

Spray-dried animal plasma (SDAP), mostly of porcine origin, is frequently used as an ingredient of weanling piglets diets in order to improve feed intake and to reduce post-weaning diarrhoea. On the basis of 15 published studies it is concluded that dietary SDAP levels up to 6 % raise both average daily gain (ADG) and feed intake (ADFI) in the first two weeks after weaning in a dose-dependent fashion. Up to 6 % SDAP also reduces feed conversion ratio (FCR). The positive effect of SDAP on ADG and ADFI is much more pronounced in the first than the second week after weaning. There is no positive carry-over effect of SDAP feeding during the period of two weeks after weaning on growth performance thereafter. SDAP is an expensive protein source and an economic evaluation should be made before including SDAP in weanling piglets diets. Multiple regression analysis indicated that, apart from SDAP dose, baseline growth rate is an important determinant of the effect of SDAP on ADG, with high baseline growth rate being associated with small effects of SDAP. It should be stressed that SDAP is a non-sterilised product that might spread certain diseases after feeding it to pigs. Porcine plasma has more beneficial effects than bovine plasma. Possible modes of action are discussed. It is suggested that, in addition to improving feed

palatability, SDAP reduces post-weaning intestinal disease by preventing attachment of pathogens.

Introduction

Weanling piglets often suffer from post-weaning diarrhoea and oedema disease. In the pathogenesis of these diseases, enteropathogenic E. coli strains play a major role (Van Beers-Schreurs et al. 1992, Nabuurs et al. 1993, Xxxxxx et al. 1997, Nabuurs 1998). Low feed intake and post-weaning diarrhoea, which both occur during the first two weeks after weaning, have a negative impact on growth performance. Various measures are taken to improve feed intake and health after weaning. Amongst these measures is the addition of specified substances to the weanling piglet diet. One of these substances is spray dried animal plasma (SDAP), which usually is of porcine origin (SDPP) as a by-product of slaughter plants. An anticoagulant is added, usually sodium citrate, to the blood from slaughtered pigs and the erythrocytes are removed by centrifugation. The plasma obtained is subsequently spray-dried and used for the production of both human foodstuffs and animal feeds (Howell and Xxxxxx 0000, Xxxxxx 1990).

The type of protein in the diet of weanling piglets has consequences for feed intake, weight gain, nitrogen digestibility and pancreatic enzyme activity (Makkink et al. 1994a, Xxxxxxx et al. 1994b, Xxxxxxx et al. 1996). The typical composition of SDAP is given in Tables 1 and 2.

Table 1

Composition (% of product) of various spray-dried animal plasma (SDAP) preparations in comparison with that of casein and soybean protein concentrate

Component	SDAP a	SDPP*b	Freeze dried porcine plasmac	Dried porcine plasmac	Dried bovine plasmac	Casein a	Soybean a protein concentrate
Dry matter	91	94.6	90.8	91.1	91.6	91	90
Crude protein	78	87.5	68	70	70	89	64
Crude fat	2	1	2	1.5	1.5	0.8	3
Ash	n.g.	5	11.5	11.8	10.3	n.g.	n.g.
Calcium	0.15	0.09	n.g.	n.g.	n.g.	0.61	0.35
Phosphorus	1.71	0.13	n.g.	n.g.	n.g.	0.82	0.81
Sodium	3.02	3.4	5.2	5.1	5	0.01	0.05
Chloride	1.5	n.g.	n.g.	n.g.	n.g.	0.04	n.g.
Potassium	0.2	0.13	n.g.	n.g.	n.g.	0.01	2.2
Magnesium	0.34	n.g.	n.g.	n.g.	n.g.	0.01	0.32
* Spray-dried porcine plasma		a National Research Council (1998).				xXxxxxxx (1975)
cHowell and Xxxxxx (1983)		n.g. = not given

Table 2

Amino acid composition and apparent ileal digestibilities of various spray-dried plasma (SDAP) preparations in comparison with casein and soybean meal

Content (% of product) Apparent ileal digestibility

(%)

	SDAPa	SDPPb*	SDBPb+	Caseinc	Soybean mealc	SDAPa	Caseinc	Soybean mealc
Alanine	n.g.	4.19	3.95	2.69	2.05	n.g.	95	85
Asparagine	n.g.	7.58	8.48	6.13	5.42	n.g.	96	87
Arginine	4.55	4.47	4.70	3.02	3.46	90	94	94
Glutamine	n.g.	11.18	11.39	18.48	8.45	n.g.	96	90
Glycine	n.g.	2.80	2.91	1.68	2.01	n.g.	94	83
Histidine	2.55	2.51	2.45	2.60	1.26	91	98	89
Isoleucine	2.71	2.79	2.53	4.37	2.15	85	95	87
Leucine	7.61	7.44	7.63	8.15	3.60	84	98	87
Lysine	6.84	6.84	7.43	6.72	2.90	87	98	89
Methionine	0.75	0.62	0.95	2.52	0.65	64	98	90
Cystine	2.63	3.03	3.16	0.34	0.70	n.g.	86	82
Phenylalanine	4.42	4.43	4.25	4.37	2.38	88	99	88
Proline	n.g.	5.90	5.71	9.41	2.38	n.g.	98	89
Serine	n.g.	4.52	5.59	4.79	2.43	n.g.	91	87
Tyrosine	3.53	3.79	3.89	4.70	1.73	n.g.	99	88
Threonine	4.72	4.54	5.54	3.61	1.82	82	94	84
Tryptophan	1.36	1.36	1.45	1.09	0.61	92	97	87
Valine	4.94	5.07	5.64	5.63	2.24	86	95	86

* Spray-dried porcine plasma

+ Spray-dried bovine plasma

a National Research Council (1998)

x Xxx xxx Xxxx-Xxxxxxxxx and Binnendijk (1997)

c CVB (1999)

n.g. = not given

The protein content of SDAP is lower than that of casein and has low apparent ileal digestibilities of amino acids. However, with respect to the contents of essential amino acids, SDAP is superior to soybean protein. The provision of essential amino acids from SDAP and the requirements of piglets (National Research Council 1998) are in good agreement except for methionine, which has a relatively low level in SDAP.

After weaning, the transition from sow milk to solid feed has important nutritional consequences like a switch from fat to carbohydrates as the main source of digestible energy and a shift from highly digestible animal protein to less digestible protein of plant origin (Everts et al. 1999). Addition of SDAP instead of plant protein to diets of weaned piglets as a protein source may improve post weaning performance because the amino acid composition and protein digestibility

of SDAP are more similar to those of the proteins in sow’s milk (Xxxxxxx and Xxxxxxx 1998).

New-born piglets rely on colostrum as their sole source of serum antibodies and milk provides intestinal antibodies during most of the postnatal period (Xxxxxx 1976, Blecha 1998). Xxxxxx and Xxxxxxxx (1995) have proposed that SDPP may enhance piglet performance after weaning by improving immunocompetence due to the immunoglobulins present in SDPP.

As described below, the incorporation of SDAP into the diet can have positive effects on average daily gain (ADG), average daily feed intake (ADFI) and feed conversion ratio (FCR) in weanling piglets. SDAP is a relatively expensive protein source and experiments have therefore been carried out to determine the optimum dose. This paper presents a review of those studies. The main objective was to establish SDAP dose-response relationships on the basis of a meta analysis and to identify additional independent variables related to the response variables ADG, ADFI and FCR. In addition, an attempt is made to describe possible mechanisms by which SDAP influences growth performance.

Multiple regression analysis.

Table 3 summarises the design and outcome of published studies on the influence of feeding SDAP on growth performance in weanling piglets. The overall, mean SDAP-induced change in ADG, ADFI and FCR in the first two weeks after weaning is +26.8 % (n=68, SEM=3), +24.5 % (n=68, SEM=2.3) and –3.2 %

(n=68, SEM=1.3), respectively.

Table 3

Summary of published experiments with piglets fed spray-dried animal plasma (SDAP) during the first two weeks after weaning

Initial Performance

Percentage difference vs.

SDAP-free control

Refer- ence

Inclu- sion (% of diet)

n Age (days)

Weight (kg)

ADG$ ADFI+ FCR# ADG ADFI FCR

A 0 80	17	4.9	310	497	1.60
A 3x "	"	"	313	488	1.56	1	-1.8	-2.5*
A 6x "	"	"	287	512	1.79	-7.4	3	11.9*
A 9x "	"	"	289	532	1.85	-6.8	7	15.6*
A 12x "	"	"	268	500	1.87	-13.5	0.6	16.9*
A 0 "	18	5.3	263	402	1.53
A 8.33x "	"	"	277	470	1.70	5.3	16.9*	11.1*
A 0 "	"	"	214	251	1.18
A 8.33x "	"	"	300	399	1.34	40.2*	59.0*	13.6*
A 0 "	"	"	304	419	1.39
A 8.33x "	"	"	323	496	1.54	6.3	18.4*	10.8
A 0 "	"	"	192	269	1.43
A 8.33x "	"	"	238	352	1.48	24.0*	30.9*	3.5
A 0 120	30	7.3	155	249	1.61
A 5x "	"	"	237	391	1.65	52.9*	57.0*	2.5
A 0 "	"	"	244	363	1.49
A 5x "	"	"	343	488	1.42	40.6*	34.4*	-4.7
A 0 "	"	"	203	317	1.57
A 5x "	"	"	343	488	1.42	69.0*	53.9*	-9.6
B 0 534	21	6.4	165	206	1.27
B 2x "	"	"	206	244	1.19	24.8*	18.4*	-6.3
B 4x "	"	"	217	256	1.18	31.5*	24.3*	-7.1
B 6x "	"	"	240	290	1.22	45.5*	40.8*	-3.9
B 8x "	"	"	247	302	1.23	49.7*	46.6*	-3.1
B 10x "	"	"	255	300	1.19	54.5*	45.6*	-6.3
C 0 96	25	6.1	151	387	2.66
C 2x "	"	"	150	447	2.94	-0.7	15.5	10.5
C 4x "	"	"	236	526	2.25	56.3	35.9	-15.4
C 6x "	"	"	254	528	2.07	68.2	36.4	-22.2
C 8x "	"	"	269	547	2.03	78.1	41.3	-23.7
C 10x "	"	"	188	445	2.44	24.5	15.0	-8.3
D 0 144	24	7.2	280	330	1.12
D 4x "	"	"	360	410	1.11	28.6*	24.2*	-0.9
D 0 18	19.5	6.1	280	420	1.59
D 14x "	"	"	360	510	1.45	28.6*	21.4*	-8.8
E 0 36	n.g.	6.9	247	292	1.18
E 10x "	"	"	261	350	1.34	5.7	19.9*	13.6
E 0 "	"	"	139	213	1.46
E 10x "	"	"	261	350	1.34	87.8*	64.3*	-8.2
E 0 "	"	"	153	204	1.47

Table 3. Continued

Initial Performance

Percentage difference vs.

SDAP-free control

Refer- ence

Inclu- sion (% of diet)

n Age (days)

Weight (kg)

ADG$ ADFI+ FCR# ADG ADFI FCR

E	10x	"	"	"	261	350	1.34	70.6*	71.6*	-8.8
E	0	"	"	"	191	267	1.44
E	10x	"	"	"	345	462	1.35	80.6*	73.0*	-6.2
E	0	"	"	"	230	300	1.74
E	10x	"	"	"	345	462	1.35	50.0*	54.0*	-22.4
E	0	96	"	7.1	63	119	1.85
E	10x	"	"	"	127	209	1.65	101.6*	75.6*	-10.8
F	0	236	24	7.5	262	305	1.16
F	10x	"	"	"	266	302	1.12	1.5	-1.0	-3.4
F	0	204	21	5.9	315	389	1.23
F	10.35x	"	"	"	444	537	1.20	41.0*	38.0*	-2.4
F	10.35x	"	"	"	420	487	1.16	33.3*	25.2*	-5.7
F	13.4x	"	"	"	413	482	1.16	31.1*	23.9*	-5.7
F	13.4x	"	"	"	378	437	1.15	20.0*	12.3*	-6.5
F	0	120	"	5.3	328	390	1.18
F	10.28x	"	"	"	378	499	1.32	15.2	27.9	11.9
F	6.96y	"	"	"	327	422	1.28	-0.3	8.2	8.5

180	22	6.2	190	253	1.34
"	"	"	220	293	1.32	15.8*	15.8*	-1.5
"	"	"	263	338	1.29	38.4*	33.6*	-3.7

G 0

G 3y

G 6y

H 0 720 28 7.9 215 270 1.30

H 5x " " " 250 290 1.20 16.3* 7.4* -7.7* H 0 " " " 196 260 1.33

"	"	"	235	290	1.23	22.4*	16.0*	-5.4*
"	"	"	224	270	1.23	16.7*	8.0*	-5.4

H 5x " " " 249 310 1.26 27.0* 19.2* -5.3* I 0 960 " 7.5 192 250 1.30

I 5x

I 5y

I	3.33x	"	"	"	223	280	1.27	16.1*	12.0*	-2.3
I	1.66x	"	"	"	227	270	1.18	18.2*	8.0*	-9.2*
J	0	626	13.2	4.1	163	186	2.50
J 2x "			"	"	195	217	2.44	19.6*	16.7*	-2.4
J 4x "			"	"	204	234	2.56	25.2*	25.8*	2.4
J 6x "			"	"	212	236	2.44	30.1*	26.9*	-2.4
J 2x "			"	"	195	222	2.50	19.6*	19.4*	0
J 4x "			"	"	215	237	2.44	31.9*	27.4*	-2.4
J 6x "			"	"	209	241	2.56	28.2*	29.6*	2.4
J 2y "			"	"	182	204	2.50	11.7*	9.7*	0
J 4y "			"	"	204	219	2.38	25.2*	17.7*	-4.8
J 6y "			"	"	200	277	2.50	22.7*	48.9*	0
K 0 180			17	5	227	299	1.32
K 2.5z "			"	"	262	316	1.20	15.4*	5.7*	-9.1*
K 5z "			"	"	290	341	1.18	27.8*	14.0*	-10.6*
L 0 416			15	4.3	191	248	1.30

Table 3. Continued

Initial Performance

Percentage difference vs.

SDAP-free control

Refer- ence

Inclu- sion (% of diet)

n Age (days)

Weight (kg)

ADG$ ADFI+ FCR# ADG ADFI FCR

"	"	"	209	265	1.27	9.4	6.9	-2.3
"	"	"	232	267	1.15	21.5*	7.7	-11.5*
"	"	"	232	267	1.15	21.5*	7.7	-11.5*

L 5y

L 5x

M	0	360	19	5.3	311	296	0.95
M	7.5z	"	"	"	333	321	0.96	7.1*	8.4*	1.0
M	0	"	"	"	329	298	0.91
M	7.5z	"	"	"	337	326	0.96	2.4*	9.4*	5.8
M	0	"	"	"	295	289	0.98
M	7.5z	"	"	"	313	301	0.96	6.1*	4.2*	-1.9
M	0	"	"	"	341	291	0.84
M	7.5z	"	"	"	339	321	0.94	-0.6*	10.3*	12.3
M	0	"	"	"	272	259	0.95
M	7.5z	"	"	"	295	293	0.99	8.5*	13.1*	4.0
M	0	"	"	"	345	304	0.88
M	7.5z	"	"	"	375	342	0.91	8.7*	12.5*	3.6
N	0	45	28	7.1	138	243	2.10

N 2x "	"	"	176	276	2.34	27.5*	13.6	11.4*
N 4x "	"	"	203	294	1.49	47.1*	21.0	-29.0*
N 6x "	"	"	251	326	1.32	81.9*	34.2	-37.1*
N 8x "	"	"	188	290	1.63	36.2*	19.3	-22.4*

A = Xxxxxx and Xxxxxxxx (1995), B = Kats et al. (1994), C = Gatnau and Xxxxxxxxx (1992), D

= de Rodas et al. (1995), E = Gatnau (1990), F = Hansen et al. (1993), G = Angulo and Cubilo (1998), H = Van der Peet-Xxxxxxxxx and Binnendijk (1995), I = Van der Peet-Xxxxxxxxx and Binnendijk (1997), J = Rantanen et al. (1994), K = Xxxxxxxxx et al. (1998), L = Smith II et al. (1995), M = Xxxxxxxx et al. (1997), N = Gatnau et al. (1991)

* = statistically significant difference (P < 0.05)

x porcine plasma

y bovine plasma

z plasma of unknown origin

n.g. = not given

n = number of piglets in the experiment

$ = average daily gain

+ = average daily feed intake

# = feed conversion ratio

The data were subjected to multiple linear regression (SAS, 1988) to disclose relationships between the independent and response variables. Figure 1 shows the dose-response effects for the percentage of SDAP in the diet and percentage change in ADG, ADFI and FCR for all studies combined.

ADG 20

-10

-20

2 1

8 3

ADFI

8 3 7 11 8

2 1

20 1 1

FCR 15

-5

-10

-15

2 3 4 5 6 7 8 9 10 11 12 13 14

SDAP (% of diet)

Fig. 1. Percentage change in average daily gain (ADG) (panel A), average daily feed intake (ADFI) (panel B) and feed conversion ratio (FCR) (panel C) in piglets fed spray-dried animal plasma (SDAP) during the first two weeks after weaning. SDAP dose classes were defined as the value indicated on the x axis ± 0.5 %. For the selected ranges of SDAP dose, expressed as percentage of diet, the percentage changes versus SDAP-free controls were calculated as weighted means; the SEM is given. The number of observations is indicated above the bars.

For this analysis the data were weighed according to the number of piglets studied. The response of both ADG and ADFI is more or less consistent up to 6 % SDAP in the diet, whereas the responses to higher levels of inclusion were not clear. As to FCR, the response to SDAP seems beneficial at levels below 6 %. Again, at higher levels, the response was variable.

Regression analyses for all studies combined showed that there are no significant relationships between the dose of SDAP and the response of either ADG, ADFI or FCR. When more independent variables were included in the regression model the variance in some response variables could be correlated significantly although the explained variance was not substantial (Table 4).

Table 4

Relationships between independent variables and response variables (percentage SDAP-induced change in ADG) for the first week (subscript 1) and for the period of two weeks after weaning (subscript 1+2)*

Response variable Modela R2 P value

% Δ ADG1	55.7 + 2.73%SDAP - 0.24ADG1 control	0.73	0.0001
% Δ ADG1+2	65.22 + 3.77%SDAP - 0.29ADG1+2 control	0.54	0.0001

* SDAP = spray-dried animal plasma, ADG = average daily gain

a Models were selected by using the linear regression procedure of SAS (SAS, 1988).

As to ADG, there is a strong influence of the performance of the control group, with high values of ADG in the control group being associated with small effects of SDAP. This is illustrated in Figure 2 for ADG in the first week after weaning. It would appear that the feeding of SDAP improves ADG only when the piglets show suboptimal performance.

In general, the response of ADG to SDAP during the first two weeks after weaning is quite impressive. The beneficial effect of SDAP on ADG is associated with an increase in ADFI. As a consequence, the improvement of FCR is generally modest.

y = 61.8 - 0.17x

R2 = 0.59, P = 0.0001

% SDAP-induced change in ADG

0 000 000 000 400

ADGcontrol (g/day)

Fig. 2. Relationship between average daily gain (ADG) in control piglets and the percentage change in ADG of piglets fed spray-dried amimal plasma (SDAP) during the first week after weaning.

Effective feeding period

Most papers on SDAP feeding in piglets report ADG and ADFI for the combined first two weeks after weaning, but not for the first and second week separately. The available percentage changes in ADG, ADFI and FCR for both weeks 1 and 2 are given in Table 5. It appears that the beneficial effect of SDAP on performance is much more pronounced in the first week than in the second week after weaning.

The percentage SDAP-induced changes in ADG, ADFI and FCR in the first two weeks after weaning and during the following period, when the control and SDAP-fed piglets received identical feeds, are presented in Table 5. It can be concluded that there is no positive carry-over effect of SDAP.

Table 5

Comparison of the mean percentage spray-dried animal plasma (SDAP)-induced change in average daily gain (ADG), average daily feed intake (ADFI) and feed conversion ratio (FCR) in the first and second week after weaning (upper part) and of the first two weeks after weaning and the following weeks when the control and SDAP-fed piglets received identical feeds (lower part). For the comparisons within each row, only experiments were used in which the data from both periods were given.

Week after weaning

Week 1				Week 2
	n	Mean	SEM	n	Mean	SEM	P valuea
% Δ ADG	29	31.1	3.4	29	13.9	2.8	0.0002
% Δ ADFI	6	26.5	4.2	6	18.3	3.4	0.16
% Δ FCR	4	-24.5	7.4	4	1.1	1.7	0.01

Week after weaning

Week 1+2 Week > 3 + 4/5

	n	Mean	SEM	n	Mean	SEM
% Δ ADG	39	21	3	39	2.4	1.9
% Δ ADFI	39	20.9	2.6	39	0.9	1
% Δ FCR	39	0.3	1.2	39	-0.8	1.3

Data derived from experiments mentioned in Table 3. n = number of control-SDAP comparisons

a Model used in t-test: y = mean + week + error

Diet composition of control group

The response to SDAP may be dependent on the kind of protein used in the control diet. In most experiments, dairy proteins were used for the control feed, but soy proteins were also used. Table 6 documents that the responses of FCR and ADG to SDAP are greater when soy protein was used in the control feed instead of dairy protein. Milk proteins are generally considered to be of high value in piglet feeding. Therefore, it is surprising that in most experiments SDAP improves piglet performance even when compared with milk proteins.

Table 6

Mean percentage spray-dried animal plasma (SDAP)-induced change in average daily gain (ADG), average daily feed intake (ADFI) and feed conversion ratio (FCR) during the first two weeks after weaning as determined by the kind of protein in the control feed (upper part), source of the SDAP (middle part) and form of the diet (lower part)

Protein in the control feed

Milk protein Soy protein

	n	Mean	SEM	n	Mean	SEM	P valuea
% Δ ADG	38	23.9	3.1	14	38.1	7.3	0.04
% Δ ADFI	38	24.5	2.8	14	28.8	5.7	0.45
% Δ FCR	38	-0.1	1.4	14	-7.9	2.3	0.006

Source

Porcine SDP Bovine SDP nd Mean SEM nd Mean SEM P valueb

% Δ ADG	5	24.2	2	6	17.1	3	0.07
% Δ ADFI	5	17.9	3.9	6	18.2	7.9	0.97
% Δ FCR	5	-4.7	2.4	6	-2.5	1.1	0.45

Form

Meal diet Pelleted diet

	n	Mean	SEM	n	Mean	SEM	P valuec
% Δ ADG	12	26.1	10.3	24	21.2	2.9	0.55
% Δ ADFI	12	29.6	7.6	24	16.3	2.5	0.05
% Δ FCR	12	4.9	2.8	24	-3.8	1.2	0.002

Data derived from experiments mentioned in Table 3. n = number of control-SDAP comparisons

a Model used in t-test: y = mean + proteincontrol feed + error

b Model used in t-test : y = mean + source + error

c Model used in t-test : y = mean + form + error

d Data derived from Xxxxxxxx et al. (1994), Xxxxx et al. (1995), and Van der Peet-Xxxxxxxxx and Binnendijk (1997)

SDAP is lower in methionine than is casein (Table 2). In the published experiments, the diets were usually formulated on an iso-lysine basis and only occasionally on an iso-methionine basis. Hansen et al. (1993), Kats et al. (1994) and Xxxx et al. (1995) have suggested that insufficient absolute intake of methionine could have been the cause of the low response to SDPP in certain experiments. Low responses to dietary SDAP could also result from low intakes of other essential amino acids such as cystine, threonine and tryptophan. To exclude any effects of amino acid intake, the experimental diets should be formulated so that

the amounts of apparent, ileal-digestible amino acids are identical. Sodium citrate is frequently used as an anticoagulant. Thus, SDAP preparations may contain 2 % citrate and diets containing 10 % SDAP may contain up to 0.2 % citrate. Because citric acid might be considered as a growth promoter in swine, it could be argued that, in studies on the effects of SDAP, the control diets should be enriched with sodium citrate. However, it is unlikely that dietary citrate concentrations as low as

0.2 % would influence piglet performance.

Porcine versus bovine spray dried plasma

Hansen et al. (1993) found no response to spray dried bovine plasma (SDBP) in the first two weeks after weaning. In three other experiments, a direct comparison between SDPP and SDBP was made. The results are presented in Table 6. It can be concluded that both SDPP and SDBP improve piglet performance post weaning, but the response of ADG to SDPP is greater than that to SDBP.

Feed processing and effect of SDAP

Weanling piglets can be fed diets in either pellet or meal form. It could be suggested that the process of pelleting, during which high temperatures are reached, may damage specific bioactive components, such as immunoglobulins, in the SDAP which in turn would diminish the positive effect on performance. It appears that both meal and pelleted feed containing SDAP have a positive effect on piglet post-weaning performance (Table 6). The response of ADFI to SDAP in meal was greater than that to SDAP incorporated in pellets. FCR appears to react more favourably to SDAP in pelleted feed.

Effect on piglet health

It has been hypothesised that the feeding of SDAP reduces the incidence and/or severity of post-weaning diarrhoea. Unfortunately, health parameters were not registered in most published experiments. In two experiments, less diarrhoea was found in piglets fed SDPP during the first two weeks after weaning (Gatnau 1990, Van der Peet-Xxxxxxxxx and Binnendijk 1995). In one experiment, piglets given feeds with SDPP required less treatment against gastro-intestinal disorders during the first two weeks after weaning than did piglets that were fed diets without SDPP (Van der Peet-Xxxxxxxxx and Binnendijk 1995).

Between-experiment variation in response to SDAP

Between experiments, the response to SDAP can vary considerably (Table 3). Various factors determining the effect of SDAP, such as baseline growth and composition of the control diet, have been discussed above. It has been suggested that the response also depends on health and hygiene status (Xxxxxx and Xxxxxxxx 1995, Xxxxxxxxx et al. 1997), but this suggestion is not well substantiated other than indirectly by the negative association between SDAP effect and growth of the control group (Figure 2).

Xxxxxx and Xxxxxxxx (1995) demonstrated that the growth-enhancing properties of SDPP are unrelated to the response to antimicrobial agents, indicating that the health status of the piglets is not an important determinant of the SDAP effect.

Possible mode of action of SDAP

As to the mechanism by which SDAP enhances growth of weanling piglets, only speculative theories have been put forward. Knowledge about the mode of action could assist in identifying and/or developing feedstuffs less expensive than SDAP, but with the same properties. It is unclear whether the beneficial effects of SDAP on post-weaning ADG are caused by directly increasing feed intake or indirectly by specific bioactive components. It is likely that factors present in SDAP influence systemic and/or intestinal functions controlling growth and/or immunity.

Feed intake and digestibility

Xxxxx et al. (1994) performed a preference test in which weanling piglets could choose between diets containing either SDPP or dried skim milk. ADFI was higher for the feed containing SDPP and thus it has been suggested that the higher intake was associated with a greater palatability.

The higher ADFI by itself can explain most of the SDAP-induced increase in ADG. The latter increase is generally greater than the increase in ADFI, resulting in an improvement in the FCR. Hansen et al. (1993) found lower dry matter and nitrogen digestibilities for piglets consuming diets containing SDPP instead of dairy proteins. Knabe (1994) found lower apparent ileal amino acid digestibilities for SDPP than for blood meal. However, the impact of the lower digestibility of SDPP must be small because the feeding of diets with up to 6 % SDAP actually improves the ADG and FCR (Fig. 1).

Immunoglobulins (Ig) and insulin-like growth factor-I (IGF-I)

Xxxxxx and Xxxxxxxx (1995) have proposed that SDPP may enhance piglet performance by improving immunocompetence through Ig present in SDPP. The Ig would prevent viruses and bacteria from damaging the gut wall, resulting in a more functional intestinal wall. However, there is no evidence that SDPP is more effective in environments with a greater load of pathogenic organisms. Xxxxx et al. (1996) have hypothesised that the Ig fraction decreases exposure of the immune system to antigens, leading to decreased production of inflammatory cytokines and, in turn, to increased feed intake. There is only indirect evidence for these ideas. Ig derived from processed blood and orally administered to colostrum- deprived new-born piglets have beneficial effects on health and performance (Xxxx and Xxxx 0000, Xxxxxx 0000, Xxxxx xx xx. 1998). Extrapolating these effects to non-colostrum-deprived weanling piglets is not justified, but it is clear that Ig in SDAP can have an effect on piglet health. The response to SDPP is higher than that to SDBP (Table 6) suggesting that a specific Ig effect could be involved. Xx Xxxxx et al. (1995) did not find a difference in piglet performance for two different sources of SDPP. Thus, this provides no evidence to support the hypothesis that the effect of SDPP is based on its Ig moiety.

De Rodas et al. (1995) reported that SDPP contains high levels of immunoreactive IGF-I (0.8 ng/mg), a peptide hormone in the somatotrophic axis that is involved in the regulation of growth. However, SDPP-fed piglets showed superior performance but no change in plasma IGF-I concentrations. The authors suggested that dietary IGF-I might have influenced intestinal mucosal function and gastrointestinal growth.

Glycoproteins

Xxxxxxxx et al. (1980) described that binding of purified K88 antigen to porcine intestinal brush border membranes was inhibited by glycoproteins derived from porcine submaxillari mucins. In vitro studies have demonstrated that the oligosaccharide chains of glycoproteins obtained from plasma can act as binding sites for the fimbrial adhesins of E. coli (Xxxxxxx et al. 1993). In this way, it may be possible that attachment of F-17 expressing E. coli strains to bovine mucus and brush border membranes can be prevented by glycoproteins. These authors state that this inhibition is not due to Ig present in the plasma because neither heat denaturation, nor proteolytic digestion nor removal of the antibodies from the plasma affected this inhibitory capacity. Mouricout et al. (1990) treated diarrhoea in calves due to infection by enteropathogenic E. coli by administration of glycoprotein glycans derived from bovine plasma. The glycan moieties of the non- Ig fraction of plasma mimicked the oligosaccharide moiety of the intestinal

receptors recognised by K99 pili. The glycoprotein glycans inhibited adhesion of bacteria to the intestine and protected colostrum-deprived calves against lethal doses of enterotoxigenic E. coli. There is some evidence that the feeding of large amounts of SDPP to weaned piglets offers protection against pathogenic E. coli (Nollet et al. 1999).

Conclusions and further research

Dietary SDAP levels up to 6 % raise both ADG and ADFI in the first two weeks after weaning in a dose-dependent fashion. Up to 6 % SDAP also reduces the FCR. The positive effect of SDAP on ADG and ADFI is much more pronounced in the first than the second week after weaning. There is no positive carry-over effect of SDAP feeding during the period of two weeks after weaning on subsequent growth. In all studies with SDAP, performance is only considered during a very short period of the piglets life. Long term effects of this expensive protein source are unknown and an economic evaluation should be made before applying SDAP in weanling diets. Baseline growth rate is an important determinant of the effect of SDAP on ADG, with high values of baseline ADG being associated with small effects of SDAP. So, it should be considered to use SDAP in weanling piglets’ diets only in farms with suboptimal post-weaning performance.

There are health risks associated with the use of non-sterilised products of animal origin as feed ingredients for the same species (Horst et al. 1997). Therefore, it must be considered that the use of dietary SDAP in pigs might spread certain diseases like Classical and African Swine Fever, and Foot and Mouth disease (Mann and Sellers 1989, Van Oirschot and Terpstra 1989, Xxxxxxxxx 1989). It is recommended to only use SDPP that originates from slaughter pigs that were approved after ante- and post-mortem veterinary inspection.

The growth-promoting action of SDAP could lie in the observed increase in ADFI due to increased palatability of SDAP-containing feed. Alternatively or additionally, SDAP could have direct effects on the intestine, leading to less intestinal disease and, in turn, higher ADFI and ADG. The Ig and glycoprotein fractions of SDAP might prevent attachment of pathogens and thus support functionality of the intestine. This possible mode of action should be put to the test in vivo. Piglets fed a diet containing SDAP should show enhanced colonisation resistance against enteropathogenic bacteria. SDAP may protect against the development of mucosa damage and thus should allow less passage of inert large molecules through the intestinal wall. Experiments have to be carried out in order to either support or refute these hypotheses.

Acknowledgements

This work was supported by the BTS Fund from the Dutch Ministry of Economic Affairs.

References

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CHAPTER 3

Zootechnical aspects

CHAPTER 3.1

Growth performance and health status in weanling piglets fed spray-dried porcine

plasma under typical Northern European conditions

X.X. xxx Xxxxx , R.J.C.F. Xxxxxxx, X.X. xxx xxx Xxxx, X. Xxxxxx, A.C. Beynenb

a Co-operative Central Laboratory “CCL-Nutricontrol” of Cehave Landbouwbelang, p.o. box 107, 5460 AC Veghel, The Netherlands

b Department of Nutrition, Utrecht University, Faculty of Veterinary Medicine,

p.o. box 80152, 0000 XX Xxxxxxx, Xxx Xxxxxxxxxxx

Journal of Animal Physiology and Animal Nutrition (accepted for publication)

Abstract

The effect of inclusion of spray-dried porcine plasma (SDPP) in diets for weanling piglets was studied. The objectives were to determine whether SDPP would have positive effects on post weaning piglet performance and health under typical Northern European conditions. In experiment 1, 160 weanling piglets were assigned randomly to a control diet or a diet containing 3% SDPP, which was added at the expense of both fishmeal and dried skim milk. In experiment 2, 264 weanling piglets were assigned to a control diet containing whey protein, a diet without whey protein but with SDPP or a diet containing both whey protein and SDPP. In essence SDPP was added to the test diets at the expense of either whey protein or fishmeal. Piglets were fed the diets for 3 weeks. In experiment 1, the piglets fed the SDPP diet had a 7% higher average daily gain (ADG) and a 4 % lower feed conversion ratio (FCR) (P < 0.05) during the first 3 weeks after weaning than did those fed the control diet. There were no differences in leukocyte counts or γ -globulin. In experiment 2 there were no significant differences in ADG and

FCR among the dietary treatments. It is concluded that low amounts of SDPP in weanling diets can have positive effects on growth performance under Northern European conditions.

Introduction

A meta-analysis of published data has shown that the feeding of spray-dried porcine plasma (SDPP) improves average daily gain (ADG) and average daily feed intake (ADFI) in weanling piglets (Van Dijk et al. 2001). In two experiments, less diarrhoea was found in piglets fed SDPP during the first two weeks after weaning (Gatnau 1990, Van der Peet-Xxxxxxxxx and Binnendijk 1995). However, most of the experiments used in the meta-analysis were conducted under Northern American conditions, which could interfere with extrapolation to the situation in Northern Europe. European weanling diets differ from those used in the US in that the main starch source is wheat, barley or tapioca instead of corn; soybean meal is included in smaller quantities; their composition is based on the amount of apparent ileal digestible, first limiting essential amino acid instead of total amino acids and that they contain less antibiotics and zinc oxide. Moreover, the weaning age of piglets in Europe is generally higher than that in the US and there might be differences in hygiene status. The effect of SDPP on ADG and ADFI depends on various factors such as weaning age, background composition of the weanling diet and hygiene status (Xxx Xxxx et al. 2001). Thus, the quantitative effect of SDPP may differ between management and feeding conditions.

Milk proteins are generally considered to have beneficial effects on piglets’ performance (Xxxxxx et al. 1995). It could thus be suggested that in the presence of whey protein no further influence of SDPP would be seen. The use of SDPP in diets for weanling piglets is limited by its high price in comparison with other protein sources. Dietary SDPP has clear effects at low inclusion percentages (Xxx Xxxx et al. 2001) and thus only 3% was added to the experimental diets used in the present experiments. Blood leukocyte counts and globulin analyses can give an indication of the health status of pigs (Xxxxx and XxXxxxxxx 1977, Xxxxxx et al. 1991).

Two experiments were conducted to evaluate the effect of SDPP. The objectives were to determine whether SDPP has positive effects on post-weaning piglet performance and health status under typical Northern European conditions and to study the effect of dietary SDPP in the presence or absence of a high level of dietary whey protein.

Materials and methods

Experiment 1.

Hundred sixty weanling piglets (F2 cross-bred: GY x [Finnish X Dutch Landrace]) from the closed herd of the research station ‘Laverdonk’ (Veghel, The Netherlands) were used. The females and castrates weighed on average 8.0 kg and were 26 days of age. The experiment had a randomised complete block design with pen as experimental unit and room as block. Each room had 6 pens and each pen contained 10 piglets. The piglets were allocated to the pens so that sex, litter origin and body weight were equally distributed. Piglets did not receive creep feed during the lactation period.

Piglets were housed in environmentally regulated rooms in pens (2.60m x 1.20m) with partially slatted floors (concrete floor: 1.10m x 1.20m) and had ad libitum access to feed and water. Each pen was equipped with a nipple waterer and a one-hole self-feeder. The room temperature was 26 oC on the first day after weaning, gradually declining to 23 oC by the end of the experiment. Day light could enter the rooms.

At weaning, piglets were assigned randomly to a diet containing either 0 or 3% SDPP (Harimex, Loenen, The Netherlands). There were eight observations (pens) per treatment. The composition of the diets is presented in Table 1. To formulate the experimental diet in relation to the control diet, SDPP was substituted for portions of both fishmeal and dried skim milk. The two diets were further formulated to contain 1.03% of apparent ileal digestible lysine and 2394 kcal NE/kg. As a consequence, there were multiple, but slight differences in the ingredient composition of the two diets. The content of apparent ileal digestible lysine was balanced by adding crystalline lysine. Piglets were fed the diets, which were in pelleted form, for 3 weeks. Subsequently, i.e. from days 22 to 33 after weaning, all piglets received the same starter diet (2270 kcal NE/kg, 16.6 % crude protein). This diet met the requirements of piglets weighing 15 to 25 kg. The experimental period lasted from weaning until 33 days after weaning. After this period, the piglets were transported to the fattening stable. Piglets and content of the feeders were weighed on d 7, 21 and 33 post-weaning so as to calculate ADG, ADFI and feed conversion ratio (FCR). Faeces scores were based on the following scale: 0= normal, solid faeces; 1 = soft, looser than normal, 2 = diarrhoea and 3=liquid faeces, severe diarrhoea. Condition scores were based on a scale of: 0 (good condition; healthy appearance, short hair, shiny skin) to 3 (poor condition; unhealthy appearance, long hair, pale and dull skin). Faeces and condition scores were recorded per pen once weekly by the same person who was unaware of treatment modality.

For leukocyte counts and globulin analyses, blood was collected from 10 randomly chosen piglets per dietary treatment 3 weeks after weaning. Blood was drawn by jugular venipuncture. The analyses were executed in the laboratory of the

Animal Health Service in the Southern Netherlands according to standard procedures. Leukocytes were counted electronically in duplicate. Leukocytes were differentiated microscopically by examining 100 leukocytes. Globulins were separated by electrophoresis on cellulose acetate and quantified densitometrically.

Experiment 2.

Two hundred and sixty-four weanling piglets, similar to those described above, were used. Piglets were housed and managed as described for experiment 1. The composition of the diets is presented in Table 2. The control diet contained 8.8 % whey-protein concentrate as a source of protein. In one of the experimental diets 3 % SDPP was added at the expense of the whey-protein concentrate ingredient, when compared with the control diet. The whey-protein level was 8.8 % to achieve that the same amount of protein was brought in the diets by the two protein sources. The second experimental diet contained both 8.8% whey-protein concentrate and 3 % SDPP, SDPP replacing a portion of the fishmeal component. The diets were pelleted and contained 1.03% of apparent ileal digestible lysine and had an energy density of 2394 kcal NE/kg, these prerequisites causing slight differences in the amounts of a limited number of ingredients. The contents of apparent ileal digestible lysine, methionine, threonine and tryptophan were balanced using crystalline amino acids. Piglets were fed the diets for 3 weeks. From days 22 to 33 after weaning, all piglets received the same starter diet as described above. There were nine observations (pens) per treatment. Piglets and content of the feeders were weighed on d 21 and 33 post-weaning. Experimental procedures, measurements and scoring methods were as described for experiment 1, except for the haematological analyses.

Analytical methods. Crude protein was determined according to Xxxxxxxx (EC 22- 7-1993; nr. L 179/8-10). The analyses of crude fat (based on EC 3-9-1998; nr. L 257/23-25), crude fibre (based on EC 26-11-1992; nr. L334/35-37), moisture (based on EC 20-12-1971; nr. L279/ 8-11) and ash (based on ISO 936, 1992) were performed with gravimetrical methods. The starch content of the diets was determined polarimetrically according to Xxxxx (ISO 5554, 1993). Phosphorus was determined spectrophotometrically according to ISO 13730 (1996). Calcium, sodium, copper, iron, manganese, zinc, potassium and magnesium were analysed with atomic absorption spectrometry (ISO 6869). The amino acid content of SDPP was determined spectophotometrically.

Statistical Analysis. Analysis of variance was performed using the GLM procedures of SAS (1988). The statistical model used in experiment was Yij = mean + dieti + roomj + errorij . DF = 6 and 10 for this model in Exp. 1 and 2, respectively. In the tables, the pooled standard error of the mean (SEM) is given. The level of statistical significance was pre-set at P < 0.05.

Table 1

The composition and calculated nutrient content of the diets in experiment 1

Ingredient or nutrient	Control diet	SDPP diet
Ingredients, % on as fed basis Barley	35.00	35.00
Wheat	19.95	20.60
Corn	15.00	15.00
Fish meal	7.00	4.70
Xxxxx whey	6.50	7.50
Toasted soy beans	6.00	6.00
Dried skim milk	5.00	2.70
Fat mixture	1.80	2.10
Organic acid mixture	1.50	1.50
L-Lysine HCl premix	0.51	0.44
Premix a	0.50	0.50
Limestone	0.46	0.83
Threonine premix	0.35	-
Salt	0.30	-
DL methionine premix	0.13	0.13
Spray-dried porcine plasma	-	3.00
Calculated nutrient content, on as fed basis NE, kcal/kg	2394	2394
Crude Protein, %	18.20	18.00
Ash, %	5.50	5.60
Fat, %	5.20	5.40
Starch, %	41.00	41.10
Crude fibre, %	2.90	2.90
Digestibleb lysine, %	1.03	1.03
Digestibleb methionine plus cystine, %	0.61	0.59
Digestibleb methionine, %	0.37	0.33
Digestibleb threonine, %	0.59	0.59
Digestibleb tryptophan, %	0.19	0.21
Lactose, %	4.90	4.50
Calcium, %	0.80	0.83
Phosphorus, %	0.59	0.53
Digestible phosphorus, %	0.44	0.38
Potassium, %	0.96	1.00
Magnesium, %	0.13	0.13
Sodium, %	0.35	0.36

a Premix provided per kg of complete diet: vitamin A, 15,000 IU; vitamin D3, 1,800 IU; vitamin E, 20 mg; riboflavin, 3 mg; vitamin B12, 22.5 цg; vitamin K3, 1.1 mg, d-pantothenic acid, 8 mg; niacin, 65 mg; Fe, 80 mg; I, 0.4 mg; Co, 0.16 mg; Cu, 160 mg; Mn, 24.5 mg; Se, 0.125 mg; Zn,

150 mg; biotin, 0.04 mg; folic acid, 0.5 mg; Natuphos (phytase) 5000, 60 mg; tryptophan, 196 mg; tylosin, 40 mg.

bApparent ileal digestible

Table 2

The composition and calculated nutrient content of the diets in experiment 2

Ingredient or nutrient	Control diet	SDPP diet without whey protein	SDPP diet with whey protein
Ingredients, % on as fed basis Barley	50.00	50.00	50.00
Corn	15.00	15.00	15.00
Whey-protein concentrate	8.80	-	8.80
Spray-dried porcine plasma	-	3.00	3.00
Fish meal	7.50	7.50	4.00
Toasted soy beans	6.00	6.00	6.00
Cassava	5.00	2.00	5.00
Fat mixture	2.30	2.45	2.50
Wheat	1.80	9.40	1.80
Organic acid mixture	1.50	1.50	1.50
Limestone	0.70	0.57	0.65
Premix a	0.50	0.50	0.50
Mono sodium phosphate	0.40	0.70	0.80
L-Lysine HCl premix	0.40	0.60	0.35
DL methionine premix	0.10	0.13	0.10
Threonine premix	-	0.55	-
Tryptophan premix	-	0.10	-
Calculated nutrient content, on as fed basis NE, kcal/kg	2394	2394	2394
Crude Protein, %	17.60	17.70	17.40
Fat, %	5.97	5.97	5.92
Xxx, %	5.20	5.20	5.40
Starch, %	40.90	43.80	40.90
Crude fibre, %	3.46	3.52	3.46
Digestibleb lysine, %	1.03	1.03	1.03
Digestibleb methionine plus cystine, %	0.61	0.59	0.63
Digestibleb methionine, %	0.37	0.33	0.33
Digestibleb threonine, %	0.63	0.59	0.66
Digestibleb tryptophan, %	0.20	0.18	0.20
Lactose, %	4.30	0.00	4.30
Calcium, %	0.92	0.84	0.86
Phosphorus, %	0.63	0.64	0.63
Digestible phosphorus, %	0.39	0.39	0.39
Potassium, %	0.66	0.58	0.66
Magnesium, %	0.14	0.13	0.13
Sodium, %	0.16	0.29	0.28

150 mg; biotin, 0.04 mg; folic acid, 0.5 mg; Natuphos (phytase) 5000, 60 mg; tryptophan, 196 mg; tylosin, 40 mg. bApparent ileal digestible

Results

Experiment 1

The analysed composition of the diets (Table 3) agreed well with the calculated composition, except that the fat content of the control diet and the crude protein content of the SDPP feed were somewhat lower and higher than expected, respectively (table 1). Table 3 also shows that mineral and trace element concentrations in the two experimental diets were similar, except for iron which cannot be explained.

Table 3

Analysed composition of spray-dried porcine plasma (SDPP) and the diets in experiment 1

Nutrient	SDPP	Control diet	SDPP diet
Crude protein, %	69.1	18.4	19.1
Xxx, %	13.1	5.8	6.1
Fat, %	1.9	4.6	5.4
Crude fibre, %	-	2.8	2.8
Starch, %	-	40.7	39.6
Moisture, %	10.6	10.5	10.5
Phosphorus, %	0.13	0.64	0.60
Calcium, %	0.11	0.92	0.94
Sodium, %	4.43	0.38	0.38
Potassium, %	0.35	0.93	0.94
Magnesium, %	0.03	0.15	0.14
Copper, mg/kg	17	140	137
Iron, mg/kg	101	197	287
Manganese, mg/kg	5	54	58
Zinc, mg/kg	9	153	152

Piglets fed the SDPP diet instead of the control diet grew 11% and 6 % faster during the first 7 days and during days 8-21, respectively (Table 4). This difference in ADG was significant only during days 8-21 (P < 0.05). Piglets fed the SDPP diet had a 4% and 3% lower FCR during days 1-7 and 8-21, the difference being significant only for the latter period (P < 0.05). During the whole three-week period of feeding the experimental diets, piglets fed the SDPP diet had a 7% higher ADG (P < 0.05) and a 3 % lower FCR (P < 0.05). ADFI was not significantly influenced by feeding SDPP. During the experiment overall health status of the piglets was good and SDPP in the diet had no significant impact on condition and faecal scores (results not shown).

During days 22-33 after weaning when all piglets received an identical diet, the feeder in one pen showed aberrations. The results of this pen are not included in the data for this period.

Table 4

Criterion and days	Control diet	SDPP diet	SEM
ADG (g/day)
1-7	176	196	9
8-21	432	457*	8
1-21	339	361*	7
22-33	522	521	29
1-33	406	416	14
ADFI (g/day)
1-7	185	194	10
8-21	566	572	11
1-21	421	434	9
22-33	882	859	35
1-33	586	604	14
FCR
1-7	1.06	1.02	0.05
8-21	1.29	1.25*	0.01
1-21	1.24	1.20*	0.01
22-33	1.70	1.80	0.09
1-33	1.45	1.46	0.03

The effect of SDPP in experiment 1 on growth performance of piglets weaned when weighing on average 8 kg

* Significantly different from the corresponding value for the control diet (P < 0.05). Table 5

The effect of SDPP in experiment 1 on blood variables of piglets three weeks after weaning

	Control diet	SDPP diet	SEM
Leukocytes, nr/nl	18.1	19.9	1.8
Lymphocytes, %	61.1	66.9	4.9
Monocytes, %	0.9	1.1	0.3
Eosinophils, %	1.3	1.7	0.03
Basophils, %	0.4	0.8	0.3
Stabform neutrophils, %	0.6	0.7	0.3
Segmented neutrophils, %	35.7	28.8	4.7
Total protein g/l	50.6	52.3	1.5
Albumin, %	51.9	47.9*	1.4
α -globulin, %	21.8	22.8	0.8
β -globulin, %	19.0	20.6	0.7
γ -globulin, %	7.3	8.7	0.5

* Significantly different from the corresponding value for the control diet (P < 0.05).

During days 22-33, there were no significant differences in the three zootechnical variables. During the whole experimental period (days 0-33) there were no significant differences in ADG, ADFI and FCR either. There were no significant diet-induced differences in faecal and condition scores after day 21 (results not shown). The blood variables are presented in Table 5. There were no significant differences between the two dietary treatments except for albumin that was significantly lower in the SDPP fed piglets than in the control piglets.

Experiment 2

The analysed composition of the diets (Table 6) was comparable to the calculated composition, with the exception of the fat content of the three diets that was higher than expected (Table 2). Mineral and trace element contents of the three diets were comparable, except for sodium.

Table 6

Analysed composition of spray-dried porcine plasma (SDPP) and the diets in experiment 2.

Nutrient	SDPP	Control diet	SDPP diet without whey protein	SDPP diet with whey protein
Crude protein, %	70.1	18.0	16.9	17.7
Xxx, %	18.5	5.6	5.2	5.6
Fat, %	2.2	6.9	7.2	7.3
Crude fibre, %	-	4.0	4.1	4.0
Starch, %	-	39.9	43.5	40.4
Moisture, %	5.6	10.0	10.1	9.9
Phosphorus, %	0.10	0.63	0.66	0.65
Calcium, %	0.06	0.87	0.77	0.77
Sodium, %	7.20	0.15	0.34	0.34
Potassium, %	0.16	0.77	0.64	0.72
Magnesium, %	0.01	0.14	0.14	0.13
Copper, mg/kg	11	156	138	135
Iron, mg/kg	44	256	240	242
Manganese, mg/kg	1	39	44	45
Zinc, mg/kg	11	198	195	171

The amino acid composition of SDPP was found to be as follows (% of product): alanine, 3.88; asparagine, 6.70; arginine, 3.96; glutamine, 9.83; glycine 2.63;

histidine, 2.12; xxxxxxxxxx, 2.65; leucine, 6.66; xxxxxx, 6.17; methionine, 0.47; xxxxxxx,

2.52; phenylalanine, 4.02; serine, 4.23; threonine, 4.35; valine, 5.00.

During the first three weeks after weaning there were no significant differences in ADG, ADFI and FCR among the dietary treatments (Table 7). On a group mean level, the SDPP diet with whey protein produced a 5 % higher ADG, 3% higher ADFI and 2% lower FCR than did the control diet containing whey protein. During days 22-33, when all piglets received an identical diet, and for the whole experimental period (days 0-33) there were no significant differences either. In the third and fourth week after weaning, the piglets fed the SDPP diet with whey protein had significantly better condition scores (P < 0.05) than did the piglets fed the SDPP diet without whey protein.

Table 7

The effects of SDPP in the absence or presence of whey protein on growth performance and condition scores of weanling piglets in experiment 2

Criterion and days*	Control diet	SDPP diet without whey protein	SDPP diet with whey protein	SEM
ADG (g/day)
1-21	316	314	331	7
22-33	000	000	000	10
1-33	391	385	396	7
ADFI (g/day)
1-21	409	416	421	11
22-33	881	848	868	13
1-33	578	570	582	8
FCR
1-21	1.30	1.32	1.27	0.03
22-33	1.70	1.68	1.71	0.03
1-33	1.48	1.48	1.47	0.02
Condition score
7	1.11	1.22	1.11	0.21
14	1.33	1.44	1.11	0.18
21	1.22ab	1.56a	1.00b	0.13
28	1.44ab	1.67a	1.11b	0.18

a, b Means within the same row without a common superscript letter differ significantly (P< 0.05)

Discussion

When SDPP was substituted for a combination of fish and milk protein in experiment 1, a positive effect of SDPP on growth performance was seen. When the diet contained whey protein and a portion of its fish meal component was replaced by SDPP (exp. 2) there was no significant effect on growth performance but group mean values improved. Taken together the results of experiments 1 and 2, it would appear that SDPP is superior to fishmeal. Thus, SDPP may be used as an alternative for fishmeal in weanling diets. The observed improvement of ADG and FCR during the first three weeks after weaning, could justify the use of SDPP in weanling piglets diets. The magnitude of the SDPP induced improvements in growth performance is not as high as found in most other experiments conducted in the USA (Xxx Xxxx et al. 2001). Possibly, the high hygiene status of our research station may be the cause of this, because it has been suggested that SDPP has a more pronounced effect under conditions with high infection pressure (Xxxxxx and Xxxxxxxx 0000, Xxxxxxxxx et al. 1997). There were no significant differences in blood values between the two dietary treatments except for albumin that was significantly lower in the SDPP fed piglets than in the control piglets. Because there were no differences in leukocyte counts or γ-globulin, of which high values are indicative for infections (Imlah and McTaggert, 1977), it can be concluded that there was no difference in health status between the two dietary treatment groups. Overall faecal and condition scores were good, losses percentages were low (0.7% and 1.6% in exp. 1 and 2 respectively) and blood variables within the standard range from which it can be concluded that the overall health status of the piglets was good.

In experiment 2, SDPP apparently was equally effective as whey protein. The addition of SDPP to the diet in combination with the omission of whey protein had no significant effect on growth performance. However, the SDPP diet without whey protein contained extra wheat protein and no lactose. Moreover, the control diet contained less sodium than the two SDPP diets. The effect of those differences cannot be ascertained with the present experimental design. On the other hand, the lack of effect of SDPP could relate to the fact that the control diet was high in whey protein. This conclusion corroborates earlier observations in that the protein source in the control diet either masks or enhances the effect of SDPP: When the control diet contained casein instead of soy protein, the incorporation of SDPP into the diet produced a smaller stimulatory effect on growth performance in weanling piglets (Van Dijk et al. 2001). Further evidence for protein interactions comes from experiment 2. Piglets fed the diet with SDPP and whey protein showed better condition scores in weeks 3 and 4 after weaning than did the piglets fed the SDPP diet without whey protein. Possibly, the use of the combination of SDPP and whey protein is beneficial on farms with health problems or unthrifty appearance of the piglets.

In both experiments, there was no carry-over effect of SDPP feeding into the subsequent feeding period. This is in accordance with literature data (Xxx Xxxx et al. 2001). This study corroborates earlier local reports (Van der Peet-Xxxxxxxxx and Xxxxxxxxxx 0000 and 1997) in that a low amount of SDPP in diets for weanling piglets can have positive effects on growth performance under Northern European conditions. Possible mechanisms by which SDPP may stimulate growth performance of weanling piglets have been described elsewhere (Xxx Xxxx et al. 2001). Probably, larger effects of SDPP on piglets’ growth performance and health would be seen under less hygienic conditions and with higher inclusion levels in the diet.

Acknowledgements

This research was partly supported by Xxxxxx, Son, The Netherlands.

References

Xxxxxx, R.D., Xxxxxxxx, G.L., 1995. The impact of environment and antimicrobial agents on the growth response of early weaned pigs to spray-dried porcine plasma. J. Anim. Sci. 73: 2532-2539.

Xxxxxx, A.R.W., Xxxxxx, I.J.R., Xxxxx, X., Xxxxxx, J.F.M. 1991. Changes in haematological and clinicochemical profiles in blood of apparently healthy slaughter pigs, collected at the farm and at slaughter in relation to the severity of pathological-anatomical lesions. Vet. Quarterly 13: 1-9.

Xxxxxx, X., 0000. Spray dried porcine plasma as a source of protein and immunoglubulins for weanling pigs. M.S. Thesis, Iowa State University.

Xxxxx, X., XxXxxxxxx, H.S. 1977. Heamatology of the pig. In: ‘Comparative clinical haematology’. Eds. Xxxxxx, R.K. and Xxxxxxxx, L.B. Xxxxxxxxx Xxxxxxxxxx Xxxx., Xxxxxx, Xxxxxx, Xxxxxxxxx, Xxxxxxxxx: 271-203.

SAS, 1988: SAS/STAT User’s Guide (Release 6.03 Ed.). SAS Inst. Inc., Cary, NC.

Xxxxxx, M. D., Xxxxxxxxx, J. E., Xxxxxxxx, L. J., Xxxxxxxx, M., Xxxx, X. X., Xxxxxxxxx,

S. G., 1995. Effect of adding fat and (or) milk products to the weanling pig diet on performance in the nursery and subsequent grow-finish stages. J. Anim. Sci. 73: 3358-3368.

Van der Peet-Xxxxxxxxx, C. M. C., Xxxxxxxxxx, G. P., 1995. The effect of spray- dried porcine plasma in diets with different protein sources on the performance of weanling piglets. Report P1.137. Praktijkonderzoek varkenshouderij. Rosmalen. The Netherlands.

Van der Peet-Xxxxxxxxx, C. M. C., Xxxxxxxxxx, G. P., 1997. Spray-dried porcine and bovine plasma and animal and plant protein in diets of weaned piglets. Report P1.185. Praktijkonderzoek varkenshouderij. Rosmalen. The Netherlands.

Xxx Xxxx, A. J., Xxxxxx, X., Xxxxxxx, M. J. A., Xxxxxx, R. J. C. F., Xxxxxx, A. C. 2001. Growth performance of weanling pigs fed spray-dried animal plasma: a review. Livest. Prod. Sci. 68: 263-274.

CHAPTER 3.2

The influence of diet composition and an anti microbial growth promoter on the growth response of weaned piglets to spray dried animal plasma

P. Xxxxxxx, X.X. xxx Xxxxx, X. Xxxxxxxxxxx, X. Fledderusa, X. Xxxxxx-Blanksmab,

A.C. Beynenc

a Institute for Animal Nutrition 'De Schothorst', X.X. Xxx 000, 0000 XX Xxxxxxxx,

Xxx Xxxxxxxxxxx

b Co-operative Central Laboratory “CCL- Nutricontrol” of Cehave Landbouwbelang, X.X. Xxx 000, 0000 XX Xxxxxx, Xxx Xxxxxxxxxxx.

c Department of Nutrition, Utrecht University, Faculty of Xxxxxxxxxx Xxxxxxxx,

X.X. Xxx 00000, 0000 XX Xxxxxxx, Xxx Xxxxxxxxxxx

Submitted

Abstract

Two separate experiments were conducted with spray dried animal plasma (SDAP) in diets for piglets from 0-14 days post-weaning. Exp. 1 was conducted to determine a possible interaction between diet composition and SDAP in diets without anti microbial growth promoter (AMGP). Exp. 2 was conducted to determine a possible interaction between SDAP and an AMGP. Both experiments comprised four treatments in a 2 x 2 factorial arrangement. The respective factors were diet composition (simple vs. complex) and SDAP (0% vs. 4%) in exp. 1 and AMGP (0 vs. 40 ppm avilamycine) and SDAP (0% vs. 4%) in exp. 2. In exp. 1 SDAP improved average daily gain (ADG) and feed conversion ratio (FCR) during the first week post weaning by 19% and 11%, respectively (P < 0.05). SDAP effects were more pronounced for the complex diet. In exp. 2, SDAP improved

feed intake, ADG and FCR during the first week post-weaning by 14, 25 and 11%, respectively (P < 0.001). SDAP tended (P < 0.1) to have more effect on ADG and ADFI for the diet without avilamycine. In conclusion SDAP in weaning diets has a positive effect on growth performance of the piglets. The magnitude of the effect depends on diet complexity and is more pronounced for diets without AMGP.

Introduction

The type of protein in the weaning diet of piglets has consequences for feed intake, weight gain, nitrogen digestibility and pancreatic enzyme activity (Xxxxxxx et al. 1994a, Xxxxxxx et al. 1994b, Xxxxxxx et al. 1996). The feeding of spray dried animal plasma (SDAP) has been shown to promote growth performance in weanling piglets (Van Dijk et al. 2001).

The use of SDAP in diets for weaned piglets in e.g. The Netherlands is limited because of the high price in comparison with other protein sources. There is an interaction between the background composition of the diet and the effect of SDAP. A meta analysis revealed that the response of average daily gain (ADG) and feed conversion ratio (FCR) to SDAP was greater when soy protein was used in the control feed instead of dairy protein (Xxx Xxxx et al., 2001). Presumably less complex diets can be formulated if SDAP is included. Therefore it was considered necessary to determine the efficacy of SDAP added to complex Northern European diets. Moreover, because of the expected reduction in the use of anti- microbial growth promoters (AMGP) in piglet diets, the effect of SDAP in diets without AMGP is of interest. A ban on AMGP may limit production and increase health disorders like diarrhoea in newly weaned piglets (Kamphues 1999). Results of Xxxxxx and Xxxxxxxx (1995) showed a larger effect of SDAP in piglets kept under poor hygienic conditions. There are indications that constituent immunoglobulins are in part responsible for the improved performance induced by SDAP (Xxxxxxxxxx-Xxxxx and Xxxxxxx 1997, Xxx Xxxx et al. 2001). It was thus hypothesised that the immunoglobulins present in SDAP reduce bacterial and viral activity in the gut and have a positive effect on the integrity of the intestinal mucosa. This hypothesis would imply that SDAP has a greater effect on growth performance of weaned piglets when it is incorporated into diets without AMGP.

SDAP shows substantial effects at relatively low inclusion rates in the diet (Xxx Xxxx et al. 2001) and it is expected that only low dosages can be economically justified. Thus, low inclusion rates of SDAP were used in the present experiments. Two experiments were conducted to evaluate the effects of SDAP as a protein source for weanling piglets. The objective of experiment 1, using weanling piglets’ diets without AMGP, was to determine a possible interaction between diet ingredients and SDAP. The objective of experiment 2 was to determine a possible

interaction between SDAP and AMGP in weaned piglets fed relatively complex diets. Avilamycine was used as a prototypical AMGP.

Materials and methods

Experiment 1

Four hundred and forty weanling piglets (F2 cross-bred: GY x [Finnish X Dutch Landrace]) from the closed herd of the research station ‘Laverdonk’ (Veghel, The Netherlands) were used. The females, males and castrates weighed on average 8.3 kg and were 26 days of age. The piglets were allocated to the pens so that sex, litter origin and body weight were equally distributed. Piglets were housed in environmentally regulated rooms in pens (2.60m x 1.20m) with partially slatted floors (concrete floor: 1.10m x 1.20m) and had ad libitum access to feed and water. Each room had 6 pens and each pen contained 10 piglets. Each pen was equipped with a nipple waterer and a one-hole self-feeder. The room temperature was 26 oC on the first day after weaning, gradually declining to 23 oC by the end of the experiment. Day light could enter the rooms.

The experiment had a randomised complete block design with pen as experimental unit and replicate as block. The experiment comprised four treatments from 0-14 days post-weaning in a 2 x 2 factorial arrangement. Within a room, pens were assigned randomly to one of the four dietary treatments. There were eleven replicates per treatment.

The experimental weanling diets that were used were: 1. a relatively simple diet,

2. a relatively complex diet, 3. the simple diet with SDAP (Appetein, APC, Ames, USA), 4. the complex diet with SDAP (Table 1). Simple and complex diets both met the energy and ileal digestible amino acid requirements for newly weaned piglets, but they differed in raw materials. The simple diets had barley, wheat, soybean meal, fish meal and potato protein as base components. The complex diets contained additionally maize, linseed meal and whey powder. SDAP was included at the expense of equal amounts of fishmeal and potato protein. Soya oil and pure amino acids were used to exclude any small differences in energy content and apparent ileal digestible essential amino acid levels among the experimental diets. The diets were pelleted and contained 10.3 g/kg apparent ileal digestible lysine and 9.84 MJ NE/kg. The contents of apparent ileal digestible methionine, lysine, threonine and tryptophan were balanced by adding crystalline amino acids. The four diets did not contain AMGP. After being fed the experimental diets, all piglets received the same starter diet from days 15-28 post-weaning. This diet was formulated to meet the requirements of weaned piglets in the rearing period from 8 to 25 kg.

Table 1

The ingredient composition and calculated nutrient content of the diets in experiment 1

Treatment	1	2	3	4
Diet composition	simple	complex	simple	complex
SDAP level	0%	0%	4%	4%
Ingredients, % on as fed basis
Barley	25.00	39.94	25.00	39.93
Wheat	50.42	20.50	50.09	21.00
Maize	-	11.20	-	10.40
Linseed meal	-	2.00	-	2.00
Soybean meal	11.00	2.00	11.00	2.00
Fish meal	2.10	3.10	-	1.00
Wheypowder	-	11.59	-	11.60
Purified potato protein	3.10	3.10	1.00	1.00
Fat mixture	0.49	1.17	0.50	1.19
Soybean oil	1.52	0.50	1.95	0.96
Molasses	2.00	2.00	2.00	2.00
Monocalcium phosphate	0.91	0.29	1.14	0.51
L-Lysine HCl premix	0.71	0.67	0.67	0.64
Premix a	0.50	0.50	0.50	0.50
Limestone	0.88	0.84	0.91	0.87
Threonine premix	0.66	0.18	0.48	-
Salt	0.47	0.03	0.51	0.09
Tryptophan premix	0.09	0.23	-	0.05
DL methionine premix	0.15	0.16	0.25	0.26
Spray-dried animal plasma	-	-	4.00	4.00
Calculated nutrient content, on as fed basis, g/kg
XX, MJ/kg	9.84	9.84	9.84	9.84
Crude Protein	181	172	182	173
Fat	37	37	39	40
Crude fibre	28	28	28	28
Starch	466	428	463	423
Digestibleb lysine	10.3	10.3	10.3	10.3
Chloride	4.8	6.2	4.7	6.1
Calcium	7.0	7.0	7.0	7.0
Digestible phosphorus	3.6	3.6	3.6	3.6
Sodium	2.5	2.6	2.5	2.6

a Premix provided per kg of complete diet: vitamin A, 7,500 IU; vitamin D3, 1,500 IU; vitamin E,

17.5 mg; riboflavin, 3 mg; vitamin B12, 20 цg; vitamin K3, 0.75 mg, d-pantothenic acid, 6 mg; niacin, 30 mg; Fe, 80 mg; I, 0.4 mg; Co, 0.15 mg; Cu, 160 mg; Mn, 24 mg; Se, 0.125 mg; Zn, 200 mg

bApparent ileal digestible

Piglets and content of the feeders were weighed on d 7, 14 and 28 post- weaning to calculate ADG, average daily feed intake (ADFI) and FCR. Faecal scores were based on the following scale: 0= normal, solid faeces; 1 = soft, looser than normal, 2 = diarrhoea and 3 = liquid faeces, severe diarrhoea. Xxxxxx scores were recorded per pen twice weekly by the same person who was blinded to treatment modality.

Experiment 2

Two hundred and eighty-eight weanling piglets (F2 cross-bred: GY x [Norwegian X Dutch Landrace]) from the closed herd of the research institute 'De Schothorst', (Lelystad, The Netherlands) were used. The females and castrates weighed on average 8.0 kg and were 26 days of age. The piglets were allocated to the pens so that sex, litter origin and body weight were equally distributed. Piglets were housed in environmentally regulated rooms in pens (2.00m x 1.10m) with partially slatted floors (concrete floor: 0.75m x 1.10m) and had ad libitum access to feed and water. Each room had 10 pens and each pen contained 6 piglets. Each pen was equipped with a nipple waterer and a self-feeder. The room temperature was 26 oC on the first day after weaning, gradually declining to 23 oC by the end of the experiment. The rooms were illuminated from 7.00 a.m. to 19.00 p.m.

The experiment comprised four treatments from 0-28 days post-weaning in a 2 x 2 factorial arrangement with twelve replicates. The experiment had a randomised complete block design with pen as experimental unit and replicate as block. The inclusion of SDAP into the diets fed during 14 days and that of AMGP during 28 days post-weaning were the treatments.

The experimental weanling diets that were used from day 0-14 were: 1. a diet without SDAP and without AMGP, 2. a diet with avilamycine as AMGP and without SDAP, 3. a diet with SDAP (Appetein, APC, Ames, USA) and without AMGP, 4. a diet with both SDAP and AMGP (Table 2). The four diets met the energy and ileal digestible amino acid requirements for newly weaned piglets. SDAP was included at the expense of fishmeal and potato protein. Renderer fat and pure amino acids were used to exclude any differences in energy content and apparent ileal digestible essential amino acid levels among the experimental diets. The diets were pelleted and contained 11.0 g/kg apparent ileal digestible lysine and

9.68 MJ NE/kg. The contents of apparent ileal digestible methionine, lysine, threonine and tryptophan were balanced by adding crystalline amino acids. From days 15-28 post-weaning all piglets received the same diet that was formulated to meet the requirements of weaned piglets in the rearing period from 8 to 25 kg. However, the piglets from treatments 1 and 3 received this diet without AMGP, whereas piglets from treatments 2 and 4 received this diet with AMGP. Thus, SDAP was included in treatments 3 and 4 from days 1-14 and AMGP was included in treatments 2 and 4 from days 1-28 post-weaning.

Table 2

The ingredient composition and calculated nutrient content of the diets in experiment 2

0-14 days post-weaning 15-28 days

Treatment	1	2	3	4	1+3	2+4
AMGP	0	40 ppm	0	40 ppm	0	40 ppm
SDAP	0 %	0 %	4 %	4 %	0 %	0 %
Ingredients, % on as fed basis
Barley	30.0	30.0	30.0	30.0	25.0	25.0
Wheat	27.8	27.8	27.8	27.8	34.9	34.9
Maize	12.4	12.4	12.4	12.4	-	-
Manioc	0.9	0.5	0.65	0.2	11.9	11.5
Linseed meal	-	-	-	-	2.7	2.7
Soybean meal	7.05	6.65	7.05	6.65	12.5	12.1
Spray dried animal plasma	-	-	4.0	4.0	-	-
Wheypowder	11.3	11.3	11.3	11.3	-	-
Fishmeal	3.1	3.1	1.1	1.1	2.15	2.15
Renderer fat	0.8	0.8	0.94	0.99	1.0	1.0
Monocalcium phosphate	0.10	0.10	-	-	0.42	0.42
CaCO3	0.25	0.25	0.42	0.42	0.1	0.1
NaCl	0.25	0.25	-	-	0.77	0.77
Protastar, potato protein	3.0	3.0	0.8	0.8	2.1	2.1
Molasses	-	-	-	-	2.5	2.5
Soybean oil	0.5	0.5	0.5	0.5	0.24	0.24
Calciumformate	0.75	0.75	0.75	0.75	0.75	0.75
Premixa	0.5	0.5	0.5	0.5	0.5	0.5
Methionine premix 10%	-	-	0.51	0.51	-	-
Xxxxxx premix 25%	0.21	0.21	0.23	0.23	0.24	0.24
Threonine premix 10%	-	-	-	-	0.73	0.73
Lys / met. premix 20/10%	0.74	0.74	0.78	0.78	1.03	1.03
Lys / try premix 00/0%	0.00	0.00	-	-	-	-
Xxxxxxx, 000,000 XXX	0.30	0.30	0.30	0.30	0.46	0.46
Avilamycine premixb	-	0.8	-	0.8	-	0.8
Calculated nutrient content, on as fed basis, g/kg

XX, MJ/kg	9.68	9.68	9.68	9.68	9.42	9.42
Crude protein	000	000	000	183	170	170
Ash	55	55	54	55	53	53
Fat	38	38	37	38	37	37
Crude fibre	27	27	27	27	35	35
Starch	405	405	405	405	426	424
c Digestible lysine	11	11	11	11	10	10
Chloride	7.0	7.0	5.8	5.8	6.5	6.5
Calcium	6.6	6.6	6.6	6.6	5.5	5.5
Dig. phosphorus	3.6	3.6	3.6	3.6	3.2	3.2
Sodium	3.3	3.3	3.3	3.3	3.5	3.5

a Premix provided per kg of complete diet: vitamin A, 7,500 IU; vitamin D3, 1,500 IU; vitamin E, 15 mg; riboflavin, 4 mg; vitamin B12, 20 цg; vitamin K3, 0.75 mg, d-pantothenic acid, 6 mg; niacin, 30 mg; Fe, 80 mg; I, 0.4 mg; Co, 0.15 mg; Cu, 160 mg; Mn, 24 mg; Se, 0.125 mg; Zn, 62 mg. b Premix provided 40 ppm of avilamycine per kg of diet. cApparent ileal digestible

Piglets and content of the feeders were weighed on d 7, 14 and 28 post- weaning to calculate ADG, ADFI and FCR. In addition faecal consistency was visually recorded twice a week by an experienced panel. Faecal scores were registered on a scale from 1-10 for which 1 = liquid stools, 10 = hard and dry stools.

Analytical methods

Crude protein was determined according to Xxxxxxxx (EC 22-7-1993; nr. L 179/8- 10). The analyses of fat (based on EC 3-9-1998; nr. L 257/23-25), crude fibre (based on EC 26-11-1992; nr. L334/35-37), moisture (based on EC 20-12-1971; nr. L279/ 8-11) and ash (based on ISO 936, 1992) were performed with gravimetrical methods. The starch content of the diets was determined polarimetrically according to Xxxxx (ISO 5554, 1993) in exp. 1 and according to ISO/CD 15159 (2000) in exp. 2. Phosphorus was determined spectrophotometrically according to ISO 13730 (1996). Calcium, was analysed with atomic absorption spectrometry (ISO 6869). Pellet hardness was determined using xxx Xxxx tester in Experiment 1 and according to Xxxxxxxxxxx in Experiment 2 (Xxxxxx and Xxx xxx Xxxx, 1996).

Statistical Analysis

Analysis of variance was performed using the GLM procedures of SAS (1988). The statistical model used in experiment 1 was Yijk = mean + blocki + feed compositionj + SDAP levelk + interaction + errorijk . The statistical model used in experiment 2 was Yijk = mean + blocki + AMGP levelj + SDAP levelk + interaction + errorijk. Faecal scores were considered as a continuous variable. The level of statistical significance was pre-set at P < 0.05. In the tables, the pooled standard error of the mean (SEM) is given.

Results

Experiment 1

The analysed composition of the diets (Table 3) agreed well with the calculated composition. The level of crude protein was somewhat low for the complex diet without SDAP.

In Table 4 the main effects for SDAP and type of diet are presented. SDAP improved ADG and FCR in the first week after weaning (P < 0.05). There were no significant effects of SDAP in the second week post-weaning. For the entire four- week period, results were similar for diets with and without SDAP. There was a small but consistent positive effect of the inclusion of SDAP on the faecal consistency in weeks 1 and 2 post-weaning.

Table 3

Analysed composition the diets used in experiment 1

Diet composition	Simple	Complex	Simple	Complex
SDAP	0%	0%	4%	4%
Component, g/kg
Crude protein	184	169	182	181
Ash	47	50	51	56
Fat	41	39	48	42
Crude fibre	26	23	26	26
Starch	442	425	437	409
Moisture	000	000	000	108
Pellet hardness, Xxxxxx	33	41	35	46

There was no effect of the complexity of the diets on growth performance. For the entire four-week period the FCR tended (P < 0.01) to be less favourable for the complex diet.

For the various measures there were significant interactions between SDAP level and diet composition (Table 4). To illustrate these effects, the results of the four dietary treatments are presented in Table 5. There was a significant interaction between diet composition and SDAP for both ADG and FCR in the second week post-weaning (Table 4). For FCR there also was a tendency towards interaction during days 1-14 (Table 4). Data in Table 5 show that SDAP improved FCR when present in the complex diet but not in the simple diet for the period of two weeks post-weaning. Similar effects, although not statistically significant, were found for FCR and ADG during week 2 and for ADFI during weeks 3-4 and weeks 1-4. In the whole 4-week experimental period, piglets that were fed the simple diet without SDAP during the first two weeks after weaning grew significantly faster than did piglets fed the complex diet without SDAP.

Feed intake in weeks 3 and 4, i.e. the period after feeding the experimental diets, was higher than expected. As a consequence, for the last two replicates there was not enough diet so that their data for weeks 3 and 4 are not included in the calculations. Piglets that were fed the complex diet containing SDAP ate more of the same diet during days 15-28 than did their counterparts that had been fed the simple diet with SDAP (Table 5). In the entire 4-week period, piglets that were fed the complex diet with SDAP during the first two weeks after weaning ate significantly more than piglets fed the simple diet with SDAP.

On day 16 after weaning, the faecal score of the piglets that had previously been fed the simple diet without SDAP was significantly worse than that for the piglets that were previously fed complex diets. On day 23 after weaning, the faecal score for the piglets that had previously been fed the simple diet with SDAP was significantly less favourable than that for the piglets that were fed earlier the complex diet with SDAP.

Table 4

The main effects of inclusion of SDAP in a simple or complex diet on growth performance of weanling piglets fed the experimental diets until 14 days post-weaning followed by feeding of the same starter diet to all piglets (Exp. 1)

Diet composition SDAP Level Statistical significancea

	simple	complex	0%	4%	SEM	Diet	SDAP	Int.
						composi
						tion
Criterion and days
ADG, g/d
1-7	135	132	123	145	7	ns	*	ns
8-14	232	229	230	232	8	ns	ns	*
15-28	393	399	403	390	9	ns	ns	ns
1-14	184	181	176	188	6	ns	ns	ns
1-28	288	281	284	285	5	ns	ns	ns
XXXX, x/d
1-7	159	157	153	163	6	ns	ns	ns
8-14	302	311	307	306	7	ns	ns	ns
15-28	580	601	596	584	12	ns	ns	t
1-14	231	234	230	235	6	ns	ns	ns
1-28	407	413	412	408	7	ns	ns	*
FCR
1-7	1.20	1.25	1.29	1.16	0.04	ns	*	ns
8-14	1.32	1.38	1.36	1.34	0.03	ns	ns	*
15-28	1.50	1.53	1.49	1.53	0.03	ns	ns	ns
1-14	1.26	1.31	1.32	1.25	0.02	*	**	t
1-28	1.42	1.48	1.46	1.45	0.02	t	ns	ns
Faecal score
2	1.36	1.36	1.45	1.27	0.09	ns	ns	ns
6	1.41	1.45	1.55	1.32	0.07	ns	*	ns
9	1.64	1.59	1.68	1.55	0.10	ns	ns	ns
13	1.17	1.17	1.22	1.11	0.09	ns	ns	ns
16	1.22	1.00	1.17	1.06	0.07	*	ns	ns
20	1.00	1.00	1.00	1.00	0.00	ns	ns	ns
23	1.33	1.08	1.17	1.25	0.10	ns	ns	t
27	1.00	1.00	1.00	1.00	0.00	ns	ns	ns

a Statistics: Int. = interaction diet composition x SDAP, ns = not significant, t = tendency, P < 0.1, * = P < 0.05, ** = P < 0.01, *** = P< 0.001.

Table 5

The individual treatment effects of inclusion of SDAP in a simple or complex diet on growth performance of weanling piglets fed the experimental diets until 14 days post-weaning followed by feeding of the same starter diet to all piglets (Exp. 1)

Diet	simple	complex	simple	complex	SEM
SDAP	0%	0%	4%	4%
Criterion and days
ADG, g/d
1-7	121	124	149	141	10
8-14	242	218	223	241	9
15-28	000	000	000	401	12
1-14	182	171	186	191	8
1-28	296a	273b	281ab	288ab	7
XXXX, x/d
1-7	152	155	167	160	8
8-14	309	305	296	316	9
15-28	602ab	591ab	557a	610b	16
1-14	230	230	231	238	8
1-28	419ab	405ab	395a	421b	9
FCR
1-7	1.27ab	1.32a	1.14b	1.18ab	0.05
8-14	1.29b	1.44a	1.35ab	1.33ab	0.04
15-28	1.50	1.49	1.50	1.56	0.04
1-14	1.27a	1.37b	1.25a	1.26a	0.02
1-28	1.43	1.49	1.42	1.47	0.03
Faecal score
2	1.45	1.45	1.27	1.27	0.14
6	1.55	1.55	1.27	1.36	0.10
9	1.73	1.64	1.55	1.55	0.14
13	1.22	1.22	1.11	1.11	0.13
16	1.33a	1.00b	1.11ab	1.00b	0.09
20	1.00	1.00	1.00	1.00	0.00
23	1.17ab	1.17ab	1.50a	1.00b	0.13
27	1.00	1.00	1.00	1.00	0.00

a,b Means within the same row without a common superscript letter differ significantly (P < 0.05).

Experiment 2

The analysed composition of the diets (Table 6) agreed well with the calculated composition although the analysed fat content was slightly higher than that calculated (Table 2). The main effects of SDAP and avilamycine are presented in Table 7. From 1-14 days AMGP did not significantly affect the variables whereas inclusion of SDAP into the diet significantly improved ADG, ADFI, FCR and

faecal scores. The effects of SDAP were most prominent from 1-7 days and diminished from 8-14 days post-weaning.

Table 6

Analysed composition of the diets used in experiment 2

0-14 days post-weaning 15-28 days

Treatment	1	2	3	4	1+3	2+4
Component, g/kg
Crude protein	183	186	184	184	169	170
Ash	52	53	51	51	50	50
Fat	42	42	41	42	49	49
Crude fibre	25	25	25	23	32	31
Starch	000	000	000	397	398	400
Moisture	141	135	139	135	140	139
Pellet hardness, Xxxxxx	24	28	33	29	11	12

The faecal consistency was significantly better on the SDAP diets during the first week post-weaning without significant effects thereafter. In week 3-4 post-weaning AMGP significantly improved ADFI and ADG. In week 3-4 post-weaning the piglets that previously had received the SDAP diet showed a lower ADFI and ADG than their counterparts that had been previously fed a diet without SDAP. Furthermore, the piglets receiving a diet with AMGP showed a higher ADG during days 15-28 than the piglets fed a diet without AMGP. The FCR for days 15- 28 was similar for all treatments. Over the four-week period, inclusion of the growth promoter into the diet tended to improve ADG without significant effects on ADFI or FCR. For the period of days 1-28 SDAP did not have a significant effect on ADG or ADFI, but significantly improved the FCR.

There were tendencies (P < 0.1) for an interaction between the effects of AMGP and SDAP. To illustrate the interactions Table 8 presents results for the individual treatments. The inclusion of SDAP into the diet had more significant effects in the absence than in the presence of AMGP. Results for days 1-7 and 8- 14 demonstrate a considerable effect of SDAP on ADFI and ADG when the diet did not contain AMGP, whereas the effects were less pronounced for the diet with AMGP. Similarly, AMGP tended to have greater effects when added to diets without SDAP. Furthermore, for the period of 1-14 days SDAP more effectively influenced performance variables than did AMGP. In general, performance variables during weeks 1-2 were significantly better when the diet contained both SDAP and AMGP instead of none of the additions. In week 3-4 AMGP increased both ADFI and ADG and tended to have a greater effect in piglets that had not previously been fed diets with SDAP. For the entire four-week period AMGP increased ADFI and ADG in piglets fed diets without SDAP, but not in their counterparts that had been fed diets with SDAP during days 1-14 post-weaning.

Table 7

The main effects of inclusion of avilamycine and SDAP on growth performance of weanling piglets (Exp. 2)

avilamycine SDAP Statistical significancea

	0	40 ppm	0	4 %	SEM	avilamycine	SDAP	Int.
Criterion and days
ADG, g/d
1-7	204	204	181	227	5	NS	***	ns
8-14	349	360	344	365	8	ns	t	ns
15-28	518	536	536	518	6	*	*	ns
1-14	272	277	258	292	5	ns	***	t
1-28	391	403	392	401	4	t	ns	ns
XXXX, x/d
1-7	211	206	195	222	4	ns	***	ns
8-14	446	454	440	459	8	ns	t	ns
15-28	769	793	794	768	8	*	*	ns
1-14	000	000	000	333	5	ns	**	t
1-28	538	550	544	544	5	ns	ns	t
FCR
1-7	1.06	1.02	1.10	0.98	0.02	ns	***	ns
8-14	1.28	1.27	1.29	1.26	0.02	ns	ns	ns
15-28	1.49	1.48	1.48	1.49	0.01	ns	ns	ns
1-14	1.19	1.17	1.21	1.15	0.01	ns	**	ns
1-28	1.38	1.37	1.39	1.36	0.01	ns	**	ns
Faecal score
week 1	6.0	5.9	5.5	6.4	0.2	ns	**	ns
week 2	5.5	5.5	5.4	5.6	0.1	ns	ns	ns
week 3-4	5.7	5.7	5.7	5.7	0.1	ns	ns	ns

a Statistics: Int. = interaction avilamycine x SDAP, ns = not significant, t = tendency, P < 0.1, *

= P < 0.05, ** = P < 0.01, *** = P< 0.001.

Table 8

The individual treatment effects of inclusion of avilamycine and SDAP on growth performance of weanling piglets (Exp. 2)

Avilamycine, d 0-28	0	40 ppm	0	40 ppm	SEM
SDAP, d 0-14	0	0	4 %	4 %
Criterion and days
ADG, g/d
1-7	176a	187a	231b	222b	7
8-14	331a	357ab	367b	362ab	12
15-28	525ab	546b	510a	526ab	8
1-14	249a	266a	295b	288b	7
1-28	383a	402b	399ab	404b	6
XXXX, x/d
1-7	194a	196a	228b	215b	6
8-14	427a	453ab	464b	455ab	11
15-28	774a	812b	762a	773a	11
1-14	303a	317ab	339c	328bc	7
1-28	531a	557b	544ab	543ab	8
FCR
1-7	1.13a	1.06b	0.99c	0.97c	0.02
8-14	1.28	1.28	1.27	1.25	0.03
15-28	1.47	1.49	1.49	1.47	0.01
1-14	1.22a	1.20a	1.15b	1.14b	0.02
1-28	1.39a	1.39a	1.36ab	1.35b	0.01
Faecal score
week 1	5.5a	5.5a	6.6b	6.2ab	0.3
week 2	5.3	5.5	5.8	5.5	0.2
week 3-4	5.6	5.8	5.7	5.7	0.1

a,b Means within the same row without a common superscript letter differ significantly (P < 0.05).

Discussion

Although SDAP was exchanged for high value protein sources in exp. 1, positive effects of relatively low inclusion levels of SDAP were apparent. This is in accordance with the outcome of a meta analysis, conducted by Xxx Xxxx et al. (2001). So, SDAP can be used as an alternative for the combination of milk proteins, fish meal and potato protein, thereby even improving ADG and FCR during the first week after weaning, which may economically justify its use. In experiment 1 there was no positive carry over effect of SDAP. This also agrees with the meta analysis (Xxx Xxxx et al. 2001). For the whole experimental period, there were no treatment effects on growth performance. It seems that piglets in the control groups compensated for the lower weight gain during the initial weeks of the experiment. In exp.1, in which no AMGP’s were present in the diets, there was

a small but systematic, positive effect of SDAP on faecal consistency. Likewise, in the experiments of Gatnau (1990) and Van der Peet-Xxxxxxxxx and Binnendijk (1995) less diarrhoea was found in piglets fed SDAP. It might be anticipated that SDAP addition to weaning piglets diets may help to prevent post-weaning diarrhoea. This would be especially relevant when AMGP are banned and, as a consequence, more gastro-intestinal disorders can be expected (Kamphues 1999).

In experiment 1, the use of a complex diet with similar nutrient content, but more high quality ingredients, did not result in an improved performance. It may be speculated that the higher pellet hardness of the complex diets, probably caused by the higher inclusion level of whey powder, caused the lack of the expected better performance. A similar suggestion was made earlier by Xxxxxxx (1993). The overall daily gain in experiment 1 was relatively low, which is presumably caused by the use of diets without AMGP’s. Inclusion of SDAP into the diet considerably improved ADG and FCR during the first week post-weaning but not in the second week after weaning. This observation corroborates the literature review by Xxx Xxxx et al. (2001). There were significant interactions between diet composition and the effect of SDAP in that SDAP generally had beneficial effects on performance when added to complex diets in stead of simple diets. We had hypothesised that SDAP would improve performance more when added to a simple diet when compared to a complex diet. Possibly, our hypothesis is not supported by the results of this experiment because of the complex diet without SDAP produced poor growth performance so that SDAP could act beneficially. The positive effect of SDAP was seen for complex diets without AMGP. Xxxxxx and Xxxxxxxx (1995) also demonstrated that the growth-enhancing properties of SDAP are unrelated to the response to antimicrobial agents.

The positive effects of SDAP on growth performance were not accompanied by a higher feed intake. This would indicate that the positive effect of SDAP on weight gain was not caused by a better palatability of the SDAP containing diets, but rather by an improvement of digestibility or absorptive capacity. Literature data generally point at an improved palatability of diets containing SDAP (Xxx Xxxx et al. 2001).

During the four-week period of experiment 2 the piglets showed on average an ADFI of 540 g/d, an ADG of 400 g/d and a FCR of 1.38. Even for the negative control treatment 1, the performance results were quite good. Inclusion of avilamycine as growth promoter into the experimental diets improved feed intake and growth rate, but not for the first two weeks post-weaning. These results are in agreement with earlier work at De Schothorst (unpublished data) in which avilamycine improved ADFI and ADG by approximately 5% during week 3-4 post-weaning, without having an effect during week 1-2. In contrast, SDAP significantly improved ADFI (by 14%), ADG (by 25%) and FCR (by 11%) during week 1 post-weaning and did also, but to a lesser extent in week 2 post-weaning, the effects being enhancements by 4%, 6% and 2%, respectively. These results are

in good agreement with those of Van der Peet-Xxxxxxxxx and Binnendijk (1995, 1997). The better palatability of the diets with SDAP, and a protective effect of immunoglobulins present in SDAP might explain the positive effects. The favourable characteristics of SDAP make it a valuable feed ingredient in diets for newly weaned piglets.

During the entire four-week period, FCR was significantly improved by the feeding of SDAP during the first two weeks, but feed intake and daily gain were not significantly affected. After the withdrawal of SDAP the piglets showed a lower group mean ADG and ADFI than those that had not received SDAP during weeks 1-2. It can be speculated that after the withdrawal of SDAP the piglets have to adapt to diets with a lower palatability and without the protective effect of the immunoglobulins. In several experiments Xxxxxx and Xxxxxxxx (1995) did not find a negative carry-over effect after withdrawal of SDAP. It is therefore of interest to study how reduced performance after the changeover in diets can be avoided. The information obtained could increase the benefit of the use of SDAP under practical conditions.

Xxxxxx and Xxxxxxxx (1995) showed larger effects of SDAP in piglets kept under poor hygienic conditions. This may indicate a protective effect of SDAP against colonisation of pathogenic bacteria. Therefore it was hypothesised that SDAP would have a bigger effect when added to diets without growth promoter, because when using diets without AMGP (pathogenic) bacteria are more likely to colonise the digestive tract. Our hypothesis is supported by the results of experiment 2. During week 1 and 2, SDAP improved ADFI, ADG and FCR by 12,

18 and 6%, respectively, when SDAP was added to the diet without growth promoter, whereas the improvements were only 3, 8 and 5% when the diet contained a growth promoter. The mechanism of the interaction between SDAP and avilamycine is not clear. Immunoglobulins from SDAP might bind bacteria and prevent bacteria and viruses from damaging the gut wall. In addition, recent data point at a reduction in intestinal inflammation after weaning piglets onto diets with porcine plasma (Jiang et al. 2000). There also was a plasma-induced reduction in weight of the small intestine (Xxxxx et al. 2000) which is characteristic for the response of animals ingesting antibiotics with the diet (Visek 1978). Our results are contradictory to those of Xxxxxx and Xxxxxxxx (1995) who reported similar effects of SDAP in diets with or without growth promoter. The reason for the discrepancy is not clear, but Xxxxxx and Xxxxxxxx (1995) used much higher levels of a combination of various antibiotics and copper sulphate than we did. In any case, the observed larger effect of SDAP in the diet without growth promoter suggests that SDAP has an extra benefit in antibiotic free diets.

Conclusions

It can be concluded from experiment 1. that a relatively low inclusion level of SDAP in weaning piglets diets without AMGP has positive effects on growth performance and possibly on health and that these effects are dependent of diet complexity. The results of experiment 2. show that SDAP in the diet can significantly improve ADFI, ADG, FCR and faecal consistency during the first two weeks post-weaning. The effect of SDAP is bigger when added to a diet without avilamycine. This indicates an increased value of plasma in diets without AMGP.

Acknowledgements

This research has been financially supported by APC Europe, S.A., Barcelona, Spain.

References

Xxxxxx, R.D., Xxxxxxxx, G.L., 1995. The impact of environment and antimicrobial agents on the growth response of early weaned pigs to spray-dried porcine plasma. J. Anim. Sci. 73: 2532-2539.

Xxxxxx, X., 0000. Spray dried porcine plasma as a source of protein and immunoglubulins for weanling pigs. M.S. Thesis, Iowa State University.

Xxxxxxxxxx-Xxxxx, J.A., Xxxxxxx, D.E., 1997. A bioassay used to identify the active fraction of spray-dried porcine plasma. J. Anim. Sci. 75: 195 (abs.).

Xxxxx, X., Xxxxx, X., Xxxxx, X., Xxx, M.Z., Xxxxxxxxxx, X. Xxxxxx, X., Xxxxxxxx, X., Xxxxxx, D.G., 2000. Dietary plasma protein reduces small intestinal growth and lamina propria cell density in early-weaned pigs. J. Nutr. 130: 21-26.

Xxxxxxxx, X., 1999. Antibiotic growth promoters in animal nutrition. Berl. Munch. Tierarztl. Wschr. 112: 370-379.

Xxxxxxx, X.X., 1993. Of piglets, dietary proteins and pancreatic proteases. PhD Thesis, Agricultural University, Wageningen.

Xxxxxxx, C.A., Xxxxxxxx, P.J., op den Kamp, B.M., Xxxx, X., Xxxxxxxxx, M.W., 1994a. Gastric protein breakdown and pancreatic enzyme activities in response to

two different dietary protein sources in newly weaned pigs. J. Anim. Sci. 72: 2843- 2850.

Xxxxxxx, X., Xxxxxxxx, X., Xxxxxxxx, X. 1996. Effects of dietary protein sources differing in solubility on total tract and ileal apparent digestibility of nitrogen and pancreatic enzymes activity in early-weaned pigs. Livest. Prod. Sci. 45: 197-208.

SAS, 1988. SAS/STAT User’s Guide (Release 6.03 Ed.). SAS Inst. Inc., Cary, NC. Xxxxxx, X., Xxx xxx Xxxx, A.F.B., 1996. Physical quality of pelleted animal feed.

1. Criteria for pellet quality. Anim. Feed Sci. Techn. 61: 89-112.

Xxx Xxxx, A.J., Xxxxxx, X., Xxxxxxx, M.J.A., Xxxxxx, R.J.C.F., Xxxxxx, A.C. 2001 Growth performance of weanling pigs fed spray-dried porcine plasma: a literature review. Livest. Prod. Sci. 68: 263-274.

Xxxxx, X.X., 1978. The mode of growth promotion by antibiotics. J. Anim. Sci. 46: 1447-1469.

CHAPTER 3.3

Pre- and postweaning performance of piglets fed pre-weaning diets containing

EITHER SPRAY-DRIED PORCINE PLASMA, WHEY PROTEIN CONCENTRATE OR WHEY POWDER

A.J. Xxx Xxxxx , X. Xxxxxx-Xxxxxxxxx, J.G.P. Xxx xxx Xxxxxx, A.C. Beynenb

a Co-operative Central Laboratory Nutricontrol Cehave-Landbouwbelang, Veghel,

The Netherlands

b Department of Nutrition, Utrecht University, Faculty of Veterinary Medicine, Utrecht, The Netherlands

Submitted

Abstract

The effect of the addition of either whey powder, spray dried porcine plasma (SDPP) or whey protein concentrate (WPC) to creep feed on pre- and post weaning performance and health of piglets was studied. The experiment had a randomised complete block design with litter as the experimental unit. Piglets remained with their littermates in the same pen after weaning. During the period from thirteen days before weaning until weaning, the piglets were offered one of three experimental creep feeds followed by the same diet after weaning. During the pre-weaning period there were no significant differences in feed intake and daily gain between the treatment groups. During the first week after weaning, the piglets that had been fed the SDPP diet before weaning, had a significantly higher average daily feed intake (ADFI) than did the piglets that were fed the WPC diet before weaning. During the fourth week after weaning, the piglets given the creep feed with SDPP before weaning had a significantly higher average daily gain (ADG) and lower feed conversion ratio (FCR) than the piglets that were fed the creep feed

with whey powder. It is concluded that the type of protein in creep feed can have positive carry-over effects on post weaning growth performance.

Introduction

Modern sow genotypes give birth to large litters of piglets that have a high growth capacity (Xxxxxxxxx and Xxxxxx 1998). Milk production of those sows is too low to accommodate the piglets’ growth potential (Xxxxxxx et al. 1993). Given the tendency towards larger litters and the limitation in milk production, it seems desirable to stimulate the intake of supplementary feed by suckling piglets. Extra feed intake would attest to the piglets’ growth capacity and would prevent a pronounced negative energy balance the lactating sow.

The feeding of diets to piglets during suckling, so called creep feeds, could be expected to have beneficial effects on piglets’ performance and health before and after weaning. However, the experiments on feeding piglets during lactation have not yielded conclusive results (Pluske 1993). Feed intake during lactation generally is small and variable and publications report either beneficial effects or no effects on piglet performance before and/or after weaning. Piglets that were fed creep feed before weaning had longer small intestinal villi after weaning than did their non-fed littermates (Nabuurs et al. 1993, Xxxxxxx et al. 1996), but this effect was not seen in an other experiment (Xxxxxxx 1986). Mean net absorption of fluid and sodium after weaning by the small intestine of piglets that had been fed creep feed was greater than in their non-fed littermates (Nabuurs et al. 1996). Possibly, piglets that receive creep feed during lactation have an improved functioning of the small intestine after weaning.

The inclusion of spray-dried animal plasma (SDAP) in a diet for weaned piglets generally has a positive effect on average daily gain (ADG) and average daily feed intake (ADFI) in comparison with other protein sources (Hansen et al. 1993, Kats et al. 1994, Xxxxxx and Xxxxxxxx 1995, Xxx Xxxx et al. 2001a). The growth promoting action of SDAP could lie in the observed increase in ADFI due to increased palatability of SDAP-containing feed (Ermer et al. 1994). Alternatively, or additionally, SDAP may have direct effects on the intestine, leading to less intestinal disease which in turn has a beneficial effect on ADFI and ADG (Xxx Xxxx et al. 2001a). Whey protein concentrate (WPC) can be used to replace SDAP in diets for weanling piglets without reducing performance (Xxxxxxxxx et al. 2000, Xxx Xxxx et al. 2001b). The effect of SDAP in diets supplied before weaning has only been described by Xxxxx and Xxx (1995), who found no significant differences in pre and postweaning growth performance between a spray dried porcine plasma (SDPP) containing creep feed (inclusion level 7.5%) compared to a fish meal and skim milk containing creep feed. However, the growth performance data in the latter experiment are relatively low and not comparable to that of high

production sow units. It could be suggested that the addition of either SDAP or WPC to creep feed may increase piglets’ feed intake before weaning. The aim of the present study was to investigate whether the addition of SDPP or WPC in creep feed influences pre- and post weaning growth performance and health.

Materials and Methods

Fifty-one litters, comprising five hundred and forty-two suckling and subsequently weaned piglets from the closed herd of the research station ‘Laverdonk’, Veghel were used. On the first day after parturition, some piglets were re-allocated to the sows so as to achieve equal litter sizes of 10 or 11 piglets per sow. The piglets (F2 cross-bred: GY x [Finnish X Dutch Landrace]) consisted of females and castrates. The male piglets were castrated at the age of 3 days. Piglets were weaned on average at the age of 25 days.

During the period from thirteen days before weaning, when the piglets weighed on average 4.5 kg, until weaning, the piglets were offered either a control diet containing 16.7 % dried whey or one of two experimental diets containing either 5.0 % SDPP (Harimex, Loenen, The Netherlands) or 13.1 % WPC (Nutrifeed, Veghel, The Netherlands). SDPP or WPC were exchanged for whey powder in the control diet on an isonitrogenous basis. The three diets were further formulated to contain 1.25 % of apparent ileal digestible lysine, 10.8 MJ NE/kg and 7.5 % lactose. The contents of apparent ileal digestible lysine, methionine, tryptophan and threonine were balanced by adding crystalline amino acids. The composition of the diets is presented in Table 1. Within parity classes of the sows, litters were assigned randomly to one of the three dietary treatments. Piglets were offered the experimental diets ad libitum in bowls to which the sows had no access.

The sows and their piglets were housed in conventional farrowing crates (2.4 m x 1.8 m). There were 6 crates per room. In the crates, the sow had a restricted area, but the piglets could roam freely. One portion of the floor of the crates consisted of concrete and the remaining area of triangular metal bars. Part of the concrete floor was heated with warm water pipes and a lamp to create a lying place for the piglets with a temperature of 27 oC. Room temperature was kept at 22 oC. Sows and piglets had free access to a water nipple. During the first eleven days of lactation, the sows were fed a commercial lactation diet (dietcode 359, Cehave, Veghel, The Netherlands), the amount supplied gradually increasing from 0.5 to

7.0 kg per day. During the subsequent days of lactation, the sows were fed this diet on ad libitum basis.

Table 1

Ingredient composition and calculated nutrient content of the creep feeds.

Item	WP	SDPP	WPC
Ingredients (% on as fed basis) Corn	41.18	43.05	43.31
Barley	10.00	10.00	10.00
Toasted soy beans	9.00	9.00	9.00
Fish meal	6.00	6.00	6.00
Soybean meal	5.00	5.00	5.00
Wheat	5.00	5.00	5.00
Whey permeate	-	9.50	0.96
Spray-dried porcine plasma	-	5.00	-
Dried whey	16.70	-	-
Whey protein concentrate	-	-	13.10
Soybean oil	2.90	2.46	2.36
Premix a	1.00	1.00	1.00
Soycomil	1.51	0.95	1.40
Monocalcium phosphate	0.51	0.79	0.77
Ca-formiate	0.60	0.60	0.60
Potassium chloride	-	0.50	0.39
Limestone	0.09	0.31	0.22
Salt	-	0.28	0.51
Flavour	0.05	0.05	0.05
Sweetener	0.03	0.03	0.03
DL-Methionine premix	0.11	0.12	0.05
L-Lysine HCl premix	0.31	0.30	0.21
Tryptophan premix	0.01	0.03	0.04
Threonine premix	-	0.03	-
Calculated nutrient content (on as fed basis) NE. MJ/kg	10.80	10.80	10.80
Crude Protein. %	21.00	21.00	21.00
Fat. %	7.38	7.00	7.15
Digestibleb lysine. %	1.25	1.25	1.25
Digestibleb methionine plus cystine. %	0.70	0.70	0.70
Digestibleb methionine. %	0.42	0.40	0.41
Digestibleb threonine. %	0.70	0.67	0.74
Digestibleb tryptophan. %	0.21	0.21	0.21
Lactose. %	7.50	7.50	7.50
Calcium. %	0.85	0.85	0.85
Digestible P. %	0.50	0.50	0.50
Sodium. %	0.42	0.42	0.42

a Main micro-nutrients provided by this premix per kilogram of complete diet: vitamin A, 12,000 IU; vitamin D3, 2,000 IU; vitamin E, 50 mg; Cu, 160 mg; avilamycine, 40 mg.

bApparent ileal digestible

After weaning, the litters were moved to environmentally regulated rooms, each containing 6 pens. The pens were 2.60 x 1.20 m with partially slatted floors (concrete floor: 1.10 m x 1.20 m). Piglets remained with their littermates in the same pen after weaning. The piglets had ad libitum access to feed and water. All piglets received the same weaner diet from weaning until 14 days after weaning (dietcode 302, Cehave, Veghel, The Netherlands) and were subsequently changed to the same starter diet (dietcode 315, Cehave, Veghel, The Netherlands) which was given until 28 days after weaning (end of the experiment). The weaner and starter diets met the requirements of piglets weighing 8 to 25 kg. Each pen was equipped with a nipple waterer and a one-hole self-feeder. The room temperature was 26 oC on the first day after weaning, gradually declining to 23 oC by the end of the experiment.

Before weaning, the piglets were weighed after birth, 13 days before weaning and at weaning. Contents of the bowls were weighed on days 13 and 7 before weaning and at weaning. Postweaning, the piglets and contents of the feeders were weighed after 7, 14, 21 and 28 days so as to calculate ADG, ADFI and feed conversion ratio (FCR).

Samples of the experimental diets and of SDPP and WPC were analysed. Crude protein was determined according to Xxxxxxxx (EC 22-7-1993; nr. L 179/8- 10). The analyses of crude fat (based on EC 3-9-1998; nr. L 257/23-25), crude fibre (based on EC 26-11-1992; nr. L334/35-37), moisture (based on EC 20-12- 1971; nr. L279/ 8-11) and ash (based on ISO 936, 1992) were performed with gravimetrical methods. The starch content of the diets was determined polarimetrically according to Xxxxx (ISO 5554, 1993). The total immunoglobulin content was determined with protein-G affinity chromatography (Pharmacia/ LKB), followed by UV detection.

Data were analysed as based on a randomised complete block design with litter as the experimental unit and parity class or birth date as block factors. There were 17 replicates (litters) per treatment. Treatments were compared using pair-wise t- tests using the general linear models procedure of SAS (1988). Xxxxxxxxxx'x and Xxxxxx'x tests were applied to check the assumptions of normality and homogeneity of variances. The statistical model used for the data before weaning was: y = mean + diet effect + parity class effect + error. The statistical model used for the data after weaning was: y = mean + diet effect + birth date effect + error. The level of statistical significance was pre-set at P < 0.05. In the tables, the pooled standard error of the mean (SEM) is given.

Results

The analysed composition of the creep feeds (Table 2) agreed well with the calculated composition (Table 1).

Table 2

Analysed composition of the protein sources and experimental creep feeds

	SDPP	WPC	WP diet	SDPP diet	WPC diet
Chemical analysis , % on as fed basis
Crude protein	82.0	34.1	20.1	20.5	20.2
Fat	0.1	0.5	6.6	6.7	6.6
Crude fibre	-	-	1.9	1.9	2.0
Moisture	7.6	3.8	11.1	11.1	10.9
Ash	5.5	6.8	6.4	6.3	6.2
Starch	-	-	35.4	35.8	36.2
Immunoglobulins, g/kg	199	12	ND	11	ND

SDPP = Spray dried porcine plasma WP = Whey powder WPC = Whey protein concentrate ND = Not detected

Growth performance before weaning is presented in Table 3. There were no significant treatment effects on feed intake and daily gain. On average, piglets fed the SDPP diet ate more during the period of 7 days before weaning until weaning than did the other two groups, but piglets fed the WPC diet grew somewhat faster than those fed the diet containing whey powder. Before weaning, the piglets were healthy and showed no signs of diarrhoea.

Table 3

The effects of protein source in creep feed on growth performance of piglets before weaning.

	Diet	WP	SDPP	W P C	SEM
Number of litters		17	17	17
ADG (g/day)
13 days before weaning until weaning		295	310	314	9
ADFI (g/day)
13 days before weaning until 7 days before weaning		8	9	9	2
7 days before weaning until weaning		17	22	18	3
13 days before weaning until weaning		12	15	13	2

See footnote to Table 1.

The results for the period after weaning are presented in Table 4. During the first week after weaning, piglets that had been fed the SDPP diet before weaning, had a higher ADFI than did the piglets that were fed the WPC diet before weaning (P < 0.05). Piglets that had been fed the diet with whey powder showed intermediate values for ADFI during the first week after weaning. As from week one after weaning, there were no significant treatment effects on ADFI. During the first 3 weeks after weaning, there were no significant treatment effects on ADG. However during the fourth week after weaning, piglets fed the SDPP creep feed had a higher ADG than the piglets that were fed the diet with whey powder before weaning (P < 0.05). The experimental creep feeds with SDPP and WPC induced a non-significant higher weight at the end of experiment (Fig 1). During the fourth week after weaning, piglets fed SDPP creep feed had a significantly better FCR than did their counterparts fed WPC creep feed. During the post- weaning period all piglets were healthy and showed no signs of diarrhoea.

WP SDPP WPC

12 25 32 39 46 53

weaning

days of age

Fig 1: Mean body weight of the piglets during the experimental period. Before weaning creep feeds with different protein sources were given; after weaning all piglets received the same diet. There were 17 litters per treatment.

SDPP = Spray dried porcine plasma WPC = Whey protein concentrate WP = Whey powder

Table 4

The effects of protein source of creep feed on growth performance of piglets after weaning when they were al fed the same diet

Diet	WP	SDPP	WPC	SEM
Number of litters	17	17	17
ADG (g/day)
Days after weaning
1-7	162	170	167	16
8-14	290	333	321	21
15-21	428	464	454	24
22-28	550a	621b	586ab	24
1-14	226	251	244	17
15-28	489	542	519	20
1-28	358	397	381	16

ADFI (g/day) Days after weaning

1-7	171ab	192a	156b	11
8-14	361	399	383	21
15-21	616	692	633	36
22-28	837	909	912	33
1-14	266	295	270	14
15-28	726	801	771	32
1-28	496	548	519	22
FCR
Days after weaning
1-7	1.12	1.18	1.06	0.06
8-14	1.19	1.23	1.23	0.05
15-21	1.50	1.51	1.40	0.07
22-28	1.54ab	1.48a	1.58b	0.03
1-14	1.20	1.19	1.15	0.04
15-28	1.49	1.48	1.48	0.03
1-28	1.39	1.38	1.36	0.02

SDPP = Spray dried porcine plasma WPC = Whey protein concentrate WP = Whey powder

a,b Means within the same row without a common superscript letter differ significantly (P < 0.05).

Discussion

We speculated that higher intakes of creep feed would be associated with higher feed intakes immediately after weaning. We also expected that the type of protein source in creep feed would affect feed intake before weaning. In the present experiment the protein-induced differences in creep feed intake were not statistically significant. However, during the week before weaning the creep feed with SDPP produced a more than 20% higher feed intake than did the creep feeds with either WPC or whey powder. There was a carry-over effect in that during the first week after weaning ADFI for the piglets fed the creep feed with SDPP was 23

% higher than for those fed the diet with whey powder. Possibly, the analysed high level of immunoglobulins in SDPP had protective and/or stimulatory effects on the intestine, leading to a better functioning of the intestine after weaning as reviewed earlier by Xxx Xxxx et al. (2001a). Alternatively, the palatability of SDPP (Xxxxx et al. 1994) could be involved. During the period of lactation palatability would enhance the intake of creep feed which in turn would facilitate the uptake of dry feed as sole source of nutrition after weaning. It should be stressed that the positive effect of SDPP on post-weaning feed intake was seen during the first week only. After the first week post weaning there was no significant influence of the type of protein in the creep feed and thus SDPP, WPC and whey powder can be considered equally effective.

During the post-weaning period there were effects of the type of protein in creep feed on ADG and FCR but the effects were limited to days 22-28. It is unknown why the carry-over effects became apparent during one specific post weaning period only. In any event, the piglets fed creep feed with SDPP had a significantly higher ADG during days 22-28 after weaning than did the piglets fed the creep feed with whey powder. Xxxxx and Xxx (1995), who conducted a comparable experiment using two experimental creep feeds (control and SDPP), found a similar, although non-significant post weaning weight gain effect for SDPP creep feed fed piglets. It is difficult to see that the higher ADG is a result of the higher ADFI during the first week. The higher ADG during days 22-28 after weaning for the piglets fed the creep feed with SDPP was associated with an unchanged ADFI and thus significantly lower FCR, at least when compared with the piglets fed creep feed with WPC. Again it should be stressed that for the entire post-weaning period there were no major differential effects on ADG, ADFI and FCR as mediated by either SDPP, WPC or whey powder in the creep feed.

It can be concluded that even within high quality protein sources in creep feed there still may be a difference in growth performance and that the protein source in creep feed can have a positive carry over effect on post weaning growth performance, but the observed effects were not systematic. Nevertheless, it would appear that the use of SDPP and/or WPC in creep feed, of which only minute amounts are consumed, might be justified for their inclusion in pre-weaning diets.

Acknowledgements

This research was supported by the Fund Eureka from the EU.

References

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Hansen, X.X., Xxxxxxx, J.L., Xxxxxxxx, R.D., Xxxxxx, T.L., 1993. Evaluation of animal protein supplements in diets of early-weaned pigs. J. Anim. Sci. 71: 1853- 1862.

Xxxxxx, R.J., Xxxxxx, M.J., Xxxx, B.D., 1993. Limitations of sow milk yield in baby pig growth. Cornell Nutrition Conference. Cornell University, Ithaca. pp 156-164.

Xxxxxxxxx, D.D.S., Xxxxxx, D.K., 1998. Genetic influences on milk quantity. In: Xxxxxxxxx, M.W.A., Xxxxxxx, P.J., Xxxxxxx, X.X. (Eds.), The Lactating Sow. Wageningen Pers, Wageningen, pp. 97-112.

Xxxxxxx, M.J.A., Xxxxxxxxxxx, X., Xxx xxx Xxxxx, E.J., Van Osta, A.L.M., 1993. Villus height and crypt depth in weaned and unweaned pigs, reared under various circumstances in the Netherlands. Res. Vet. Sci. 55: 78-84.

Xxxxxxx, M.J.A., Xxxxxxxxxxx, X., Xxx Xxxxxxxxxx-xxx xxxxxx, X., 1996. Effect of supplementary feeding during the suckling period on net absorption from the small intestine of weaned pigs. Res. Vet. Sci. 61: 72-77.

Xxxxxx, X.X., 1993. Psychological and nutritional stress in pigs at weaning: production parameters, the stress response, and histology and biochemistry of the small intestine. pp 21-22. Ph.D. Thesis. Xxxxxxxxxx xx Xxxxxxx Xxxxxxxxx.

XXX 0000. SAS/STAT User’s Guide (Release 6.03 Ed.). SAS Inst. Inc., Cary, NC.

Xxx Xxxx, A.J., Xxxxxx, X., Xxxxxxx, M.J.A., Xxxxxx, R.J.C.F., Xxxxxx, A.C. 2001a. Growth performance of weanling pigs fed spray-dried animal plasma: a review. Livest. Prod. Sci. 68: 263-274.

Xxx Xxxx, A.J., Xxxxxx, R.J.C.F., Xxx xxx Xxx, A.G., Xxxxx, X., Xxxxxx, A.C., 2001b. Growth performance and health status in weanling piglets fed spray-dried porcine plasma under typical Northern European conditions. J. Anim. Physiol. Anim. Nutr. In press.

CHAPTER 4

Small intestinal morphology and function

Jejunal cypts of piglets. BrdU positive cells, an indicator of cell mitotic activity, are visible as relatively dark-stained cells. Magnification 400 X.

CHAPTER 4.1

Small intestinal morphology in weaned piglets fed a diet containing spray-dried porcine plasma

X.X. Xxx Xxxxx, X.X. Xxxxxxxx, X.X.X.X. Xxxxxxx, X.X.X. Xxx Xxx Xxxxxx,

M.J.A. Nabuursb, N. Stockhofe-Zurwiedenb, A.C. Beynenc

aCo-operative Central Laboratory “CCL- Nutricontrol” of Cehave Landbouwbelang, X.X. Xxx 000, 0000 XX Xxxxxx, Xxx Xxxxxxxxxxx,

bDepartment of Immunology, Pathobiology and Epidemiology, Institute for Animal Science and Health, ID-Lelystad, X.X. Xxx 00, 0000 XX Xxxxxxxx, Xxx Xxxxxxxxxxx,

cDepartment of Nutrition, Utrecht University, Faculty of Xxxxxxxxxx Xxxxxxxx, X.X. Xxx 00000, 0000 XX Xxxxxxx, Xxx Xxxxxxxxxxx

Research in Veterinary Science (accepted for publication, available online at 'xxxx://xxx.xxxxxxxxxxx.xxx doi: 10.1053/rvsc.2001.0478)

Abstract

The hypothesis tested in this study was that the reported beneficial effects of spray-dried porcine plasma (SDPP) on piglet post-weaning performance and health are associated with a trophic effect on small intestinal mucosa. At 24 days of age, the piglets of 7 sows were assigned to one of three treatment groups. One group remained to be suckled. The other two groups were weaned and offered a diet containing either 15% SDPP or casein. From each treatment group, one piglet was anaesthetised and samples were taken from the small intestinal wall at 26, 28 and 31 days of age. There were no significant effects of SDPP versus casein on villus length. On average, there was less mitotic activity in the SDPP-fed piglets than in those fed casein on days 4 and 7 after weaning. Because less mitotic activity leads to less immature enterocytes, this may provide a mechanism for the reported beneficial effects of SDPP on performance and health.

Introduction

In weaned piglets, diarrhoea occurs frequently during the first two weeks after weaning at the age of 21-28 days, which causes impaired growth performance and high mortality. The diarrhoea is associated with the proliferation and activity of enterotoxigenic E. coli and low feed intake in the first week after weaning (Van Beers-Schreurs et al. 1992). Histological examination of the small intestine has shown that weaning is associated with a marked hyper-regeneration following villus atrophy (Xxxx and Xxxxx 1989). The villus atrophy impairs digestive and absorptive function of the gut, contributing to poor performance after weaning (Hampson and Kidder 1986, Nabuurs et al. 1994, Xxxxxx et al. 1997). Xxxxx et al. (1991), Xxxxxx et al. (1996) and Xxx Xxxxx et al. (1998) demonstrated that higher feed intake after weaning results in less villus atrophy.

Xxxxxx et al. (1997) suggested that cell-kinetic changes after weaning are similar to those described in starvation followed by re-feeding, which caused a decreased cell production rate in the crypts followed by an increase (reviewed by Xxxxxx et al. 1997). An increased mitotic activity results in more immature enterocytes (Xxxx and Xxxxxx 1992), leading to an impaired digestive and absorptive function (Xxxxxxx et al. 1983, Xxxxx 1984, Xxxxx 1985, Xxxx and Xxxxxx 1992) and increased sensitivity to bacterial toxins and increased toxin migration through the enterocyte membrane (Xxxxxx et al. 1991, Xxx and Xxxxxx 1993, Nabuurs et al. 1994). As suggested by Xxxxxxx (1986) and Xxxxxxx et al. (1994), these effects explain the increased susceptibility of the piglet to diarrhoea and growth depression in the post-weaning period.

Various measures are taken to improve feed intake and health of piglets after weaning. Amongst these is the addition of specific substances to the weaner pig diet. One of these substances is spray-dried animal plasma (SDAP) which usually is of porcine origin.

The addition of SDAP to diets of weaned piglets generally has a positive effect on average daily feed intake (ADFI) and average daily gain (ADG) (Van Dijk et al. 2001). In two experiments, less diarrhoea was found in piglets fed spray-dried porcine plasma (SDPP) during the first two weeks after weaning (Gatnau 1990, Van der Peet-Xxxxxxxxx and Binnendijk 1995).

Several studies have been conducted to unravel the mode of action of SDAP. The growth promoting action of SDAP could lie in the observed increase in ADFI due to increased palatability of SDAP-containing feed (Ermer et al. 1994). Alternatively, or additionally, SDAP may have direct effects on the intestine, leading to less intestinal disease which in turn has a beneficial effect on ADFI and ADG (Xxx Xxxx et al. 2001). It could be hypothesised that SDPP prevents post weaning villus atrophy by a protective or trophic effect on the small intestinal epithelium. It

may be possible that SDAP contains active components like Epidermal growth factor or Insulin like growth factor-1, that are trophic to the small intestinal villi, as described for milk products by Xxxx et al. (1996). There are four reports in abstract form on the effect of feeding SDAP on small intestinal morphology in weaned piglets (Cain et al. 1992, Xxxxxx xx xx. 0000, Xxxxxxxxx xx xx. 0000, Xxxxxxx xx xx. 1997). However, the experimental designs and methods used are not described in detail and the outcomes of the experiments are contradictory. Therefore we examined the effects of dietary SDPP not only on small intestinal morphology, but also on enterocyte mitotic activity in piglets during the first week after weaning. Two groups of weaned piglets were fed a diet containing either 15% SDPP or casein. A third group of piglets remained with the sow. Thus, it was expected that our experiment would provide information about the extent to which the feeding of SDPP may normalise intestinal morphology and enterocyte mitotic activity. High concentrations of SDPP in the diet have considerable positive effects on piglet post weaning performance (Xxx Xxxx et al. 2001) and by using a high level in the experimental diet, we anticipated that maximum trophic or protective effects on the small intestinal mucosa would be seen. Casein is generally considered to be a high value protein source for piglets. As a control protein for SDPP, casein may not enhance the contrast, but it does exclude possible confounding effects on small intestinal morphology because, unlike plant protein sources, casein would be expected not to damage the intestinal epithelium (Xxxx and Xxxxx 1989).

Materials and methods

Animals and design

Animal care and use. The experimental design was approved by the Animal Experiments Committee of ID-Lelystad.

Seventy piglets from the closed herd of the research station ‘Laverdonk’, Veghel were used. The piglets (F2 cross-bred: GY x [Finnish X Dutch Landrace]) were females and castrates aged 24 d with average weight of 7.9 kg. The experiment had a complete randomised block design with each block consisting of 10 piglets from the same litter. At the age of 24 days, the piglets of 7 sows were assigned randomly to one of three treatments. One group (3 piglets per litter) remained on the sow. Two groups were weaned and offered a diet containing either SDPP (3 piglets per litter) or casein (3 piglets per litter). To obtain baseline values, at the age of 24 days, one randomly chosen piglet from each litter was anaesthetised to provide samples of the small intestinal wall and was killed immediately afterwards. From each treatment group, one randomly chosen piglet from each sow was sampled and killed at 26, 28 and 31 days of age. As a result, there were 21 piglets for each feeding treatment.

Housing Environments. The piglets that had been weaned were kept in groups of 3 animals (per dietary treatment) from the same litter. The groups were housed in pens (2.60m x 1.20m) with rubber-coated, expanded metal floors. The pens were placed in an environmentally regulated nursery. The piglets had free access to feed and water. Each pen was equipped with a water nipple and a feeding bowl. The room temperature was 26 oC. The unweaned piglets were housed with their dam in conventional farrowing crates (2.4 m x 1.8 m). In the crates, the sow was restricted to one area and the piglets could roam freely. One part of the floor of the crates consisted of concrete and the other part of triangular metal bars. Room temperature was kept at 22 oC. Piglets had free access to a water nipple. No creep feed was provided.

Feeding. The composition of the experimental diets is shown in Table 1. The diets, which were in meal form, contained either 15% (w/w) casein or SDPP. The diets were formulated to contain 1.32 % apparent ileal digestible lysine and 2394 kcal NE/kg.

Measurements.

Individual body weight was measured at 24, 26, 28 and 31 days of age. For the piglets that were weaned, feed intake per group was measured daily from 24 to 31 days of age.

The crude protein content of the feed was determined according to Xxxxxxxx (EC 22-7-1993; nr. L 179/8-10). The analyses of fat (based on EC 3-9-1998; nr. L 257/23-25), crude fibre (based on EC 26-11-1992; nr. L334/35-37), moisture (based on EC 20-12-1971; nr. L279/ 8-11) and ash content (based on ISO 936, 1992) were performed with gravimetrical methods. The starch content of the feed was determined polarimetrically according to Xxxxx (ISO 5554, 1993). The total immunoglobulin content of SDPP and the feed was determined with protein-G affinity chromatography (Pharmacia/LKB), followed by UV detection.

To assess cell mitotic activity, the incorporation rate of 5-bromo-2’- deoxyuridine (BrdU) into the small intestinal enterocytes was determined by an immunocytochemical technique (Xxxxxxx-Xxxxxx and Xxxxxxxx 1986, Dolbeare 1995). The piglets received BrdU (Sigma-Aldrich Fine Chemicals, B-5002) by intraperitoneal injection. Each animal received a volume of 5 ml, which contained 40 mg BrdU/ml saline, two hours before sampling the small intestine.

Before samples from the small intestine were taken, the piglets were anaesthetised with a mixture of nitrous oxide, oxygen and halothane administered through a facemask. Five intestinal tissue samples of 2 cm length each were removed along the small intestine. One sample was taken adjacent to the stomach at 10 per cent of the length of the small intestine. The other four samples were taken further distally at 25, 50, 75, and 95 per cent of the length of the small intestine. The tissue was cut at the contra-mesenteric side and pinned with the serosal side on a piece of cork. After the samples had been taken, the piglets were

euthanised by an intracardial injection of T61 (Hoechst Roussel Vet, Brussels, Belgium).

Table 1.

Composition of the experimental diets

Control SDPP

Ingredient composition Spray-dried porcine plasma	% on as fed -	basis 15.00
Casein	15.00	-
Dried whey	10.00	10.00
Monocalcium phosphate	0.88	1.60
Limestone	1.02	0.60
Soybean oil	1.30	1.70
Premixa	0.50	0.50
Barley	40.00	20.30
DL-Methionine	-	0.30
Corn	30.80	50.00
Salt	0.50	-
Calculated composition NE kcal/kg	2394	2394
Crude protein, %	23.40	22.50
Fat, %	3.50	4.20
Crude fibre, %	2.50	2.00
Digestibleb lysine, %	1.37	1.32
Digestibleb methionine plus cystine, %	0.73	0.73
Digestibleb methionine, %	0.54	0.34
Digestibleb threonine, %	0.84	0.83
Lactose, %	5.00	5.00
Calcium, %	0.73	0.74
Digestibleb phosphorus, %	0.40	0.41
Sodium, %	0.50	0.50

a Premix provided per kilogram of complete diet: vitamin A, 7,500 IU; vitamin D3, 1,500 IU; vitamin E, 17.5 mg; riboflavin, 2 mg; vitamin B12, 20 µg; vitamin K3, 0.75 mg, d-pantothenic acid, 6 mg; niacin, 30 mg; iron, 80 mg; iodine, .45 mg; cobalt, .15 mg; copper, 160 mg;

manganese, 24 mg; selenium, .175 mg; zinc, 150 mg; zincbacitracin, 50 mg.

bApparent ileal digestible

The tissue samples were fixed in 10 per cent neutral buffered formalin with the mucosal side downwards so that the villi were fixed vertically. After fixation, a portion of the sample was embedded in paraffin wax by standard techniques. From each sample, two transverse sections were selected, stained with

haematoxylin and eosin and examined with a binocular microscope using an ocular micrometer. Length and depth of at least 10 villi and crypts were measured in each sample (Nabuurs et al. 1993). An immunohistochemical technique was used to stain cells labelled with BrdU. Tissue sections of about 4 µm thickness were deparaffinized and rehydrated, endogenous peroxidase was blocked and sections were treated with 0.1 % proteinase K (Sigma P-6556). Sections were first incubated with a monoclonal antibody against bromodeoxyuridine (Dako X0902, 1:15 dilution, room temperature) followed by an incubation with a biotinylated secondary antibody (rabbit-anti-mouse, Dako E0413, 1:200 dilution, room temperature). An incubation with a streptavidin/biotin complex (Dako P 0397) and diaminobenzidine (DAB, Sigma D 5637) as substrate were used to visualise binding of the first antibody. Stained cells showed x xxxxx to darkbrown colour and were counted in ten randomly selected crypt-areas of 0.062 mm2 per specimen by light microscope at a magnification of 400 fold. This immuno-stain was applied on the samples taken at 10, 25, 50, and 75 per cent of the length of the small intestine. Histological examination was done by one person while he was blinded to treatment modality.

Statistical Analyses

Pen was the experimental unit for growth performance data. The individual pig was considered as experimental unit for the data from small intestinal morphology and mitotic activity. Growth performance and villus-crypt data were analysed using the model: y = mean + sow effect + treatment effect + error. Mitotic activity data were analysed using the model: y = mean + treatment effect + error. Sow as block factor was left out of the latter model because, due to absence of staining of some BrdU samples, the number of piglets originating from one sow was not equal for each treatment. Crypt depth and villus length data are all based on 7 replicates (individual piglets) per treatment-day combination. Statistical analysis was performed using the general linear models procedure of SAS (1988). The level of statistical significance was pre-set at P < 0.05. Xxxxxxxxxx'x and Xxxxxx'x tests were applied to check the assumptions of normality and homogeneity of variances.

Results

The data presented in Table 2 show that the analysed values for feed composition were similar to those calculated (Table 1).

For ADG data some in-equalities of variance were found. After log transformation of the ADG data the variances were found to approach equality so that further statistical analyses were performed with the transformed data. During

the first 4 days, the unweaned piglets grew much faster than the weaned piglets. (Table 3).

Table 2.

Chemical analysis of the experimental diets

control SDPP

Chemical analysis % on as fed basis

Crude protein	23.4	21.0
Fat	3.1	3.9
Crude fibre	3.3	2.6
Moisture	10.3	10.8
Ash	5.3	5.3
Starch	39.8	43.1
Immunoglobulins (g/kg)	4.0	37.0

Table 3.

Daily weight gain in the three treatment groups and feed intakes in the weaned piglets

Unweaned piglets

Weaned

piglets

Measure		Control diet	SDPP diet	SEM
Average Daily Gain, g
Days1 24-25	597a	36b	16b	40
DAYS 26-27	411a	228b	239b	46
Days 28-30	212	240	158	55
Average Daily Feed Intake, g
Day 24		4	13	5
Day 25		16	33	9
Day 26		118	124	19
Day 27		170	202	24
Day 28		217	173	37
Day 29		301	217	66
Day 30		260	278	43

Data presented as means for 6 or 7 animals and pooled SEMs.

1Days refer to age of the piglets. Piglets were weaned at the age of 24 days.

a,b Means within the same row without a common superscript letter differ significantly (P < 0.05).

There were no significant differences in ADG between unweaned and weaned piglets during the last 3 days of the experiment. For the weaned piglets, there was no significant diet effect on ADG. ADFI was similar for the two dietary treatments.

Villi were significantly shorter in the weaned than unweaned piglets at the age of 26 and 28 days (Fig. 1). No such difference in villus length was seen at the age of 31 days. Diet composition did not significantly influence the villus length reduction seen immediately after weaning.

At the ages of 26 and 28 days there were no differences in crypt depth among treatments (Fig. 2). At the age of 31 days however, the unweaned piglets generally showed shorter crypts than did their weaned counterparts groups. The difference was statistically significant for the site at 75% of the length of the small intestine.

The villus-height/crypt-depth ratio is presented in Figure 3. The ratio was systematically higher in the unweaned piglets than in the weaned piglets. There was no significant diet effect in the weaned piglets. At days 4 and 7 after weaning, the overall mean villus-height/crypt depth ratio was higher for the weaned piglets fed the SDPP diet instead of the casein diet, but the difference was not significant.

BrdU data are based on 3-7 replicates per treatment. In 66 out of the total of 280 samples there was absence of staining and those samples were excluded from the calculations. The excluded samples consisted of 9, 30 and 27 samples of the unweaned, casein and SDPP fed groups, respectively. It was concluded that the major cause of the absence of staining was erroneous injection of BrdU into the bladder or the intestinal lumen because there was a total absence of BrdU incorporation in either the mucosa or submucosa. At the age of 26 days, the overall mean numbers of BrdU-labelled epithelial cells in the small intestine were significantly lower in the weaned piglets than in their unweaned counterparts (Fig. 4). However, at the ages of 28 and 31 days, the overall mean number of BrdU- labelled cells was lower in the unweaned group than in the weaned groups. This difference was significant at the age of 31 days. At day 7 after weaning, piglets fed SDPP generally showed less mitotic activity than did the piglets receiving the casein diet; the difference only reached statistical significance for the site at 25% of the length of the small intestine. For the piglets aged 26, 28 and 31 days, linear regression was done for the number of BrdU-labelled epithelial cells and either villus length or crypt depth. The analysis was carried out with the mean values of all five sites for the entire small intestine. Only at 26 days of age these relationships were found to be statistically significant (Fig. 5).

abb abb

abb

abb abb

abb

suckling

casein SDPP

800

700

600

villus height µ m

500

400

300

200

mean

100

sites

days of age 24

26 28 31

Fig 1: Villus height (+SEM) at the 25% and 75% sites along the entire length of the small intestine and the mean villus height of all sites of unweaned piglets and weaned piglets given either a casein or SDPP containing diet. Days refer to age of the piglets. Weaning was done at the age of 24 days. a,b Bars, within each set of comparable data without a common superscript letter differ significantly (P < 0.05).

180

160

140

Crypt depth µ m

120

100

sites

suckling casein SDPP

abb

a b ab

mean

days of age 24 26

28 31

Fig 2: Crypt depth (+SEM) at the 25% and 75% sites along the entire length of the small intestine and the mean crypt depth of all sites of unweaned piglets and weaned piglets given either a casein or SDPP diet. Days refer to age of the piglets. See also legend to Fig. 1.

abb

suckling

casein SDPP

abb abb

abb

a b ababb

a b ab

ratio

mean

sites

days of age 24 26

28 31

Fig 3: Villus height-Crypt depth ratio (+SEM) at the 25% and 75% sites along the entire length of the small intestine and the mean ratio of all sites of unweaned piglets and weaned piglets given either a casein or SDPP diet. See also legend to Fig. 1.

abb

aba

abb

suckling casein SDPP

number of BrdU positive cells

140

120

100

mean

sites

days of age 24 26 28 31

Fig 4: Number of BrdU positive epithelium cells (+SEM) at the 25% and 75% sites along the entire length of the small intestine and the mean number of all sites of unweaned pigs and weaned piglets given either a casein or SDPP diet. See also legend to Fig. 1.

200

180

160

crypt depth

140

120

100

0 10 20 30 40 50 60 70 80

n BrdU positive cells

900

800

700

villus height

600

500

400

300

200

100

0 10 20 30 40 50 60 70 80

n BrdU positive cells

Fig 5: The relationship between the average number of BrdU positive epithelial cells and either crypt depth or villus height (µm) at day 26 of age. Model equations were: Crypt depth = 95.7 +

0.8 x number of BrdU positive cells (R2=0.65, P=0.002) and Villus height= 267 + 5.8 x number of BrdU positive cells (R2=0.65, P=0.002).

Discussion

This report describes the effect of dietary SDPP on small intestinal morphology and enterocyte mitotic activity in weaned piglets. Unweaned piglets served as reference. In our study there was no positive effect of SDPP on ADFI and ADG in the first week after weaning. This may be explained by the adequate ADFI and ADG in the control group for the age interval of 24 – 30 days. Xxx Xxxx et al. (2001) demonstrated in a meta analysis that high baseline ADG and ADFI values

are associated with a lack of effect of SDAP. Because SDPP did not affect ADFI, this experiment is suitable to identify specific trophic effects of SDPP, if any. A change in feed intake would by itself alter villus height (Xxxxx et al. 1991, Pluske et al. 1996, Xxx Xxxxx et al. 1998).

The finding that villi were significantly shorter in the weaned piglets versus unweaned piglets is in accordance with the experiments of Nabuurs et al. (1993) and Xxx Xxxxx et al. (1998). However, contrary to the experiments of Xxxxxxx et al. (1993) and Xxx Xxxxx et al. (1998), the shorter villi in weaned piglets were not seen at 7 days after weaning in our experiment. Possibly in this experiment the adequate consumption of good quality feed had caused an increase in mitotic activity, resulting in increased villus height. In the weaned piglets, there was no significant effect of dietary SDPP on villus length, indicating that that SDPP has no specific trophic effects to small intestinal villi. This is in accordance with the outcome of an experiment of Xxxxx et al. (2000).

At the age of 26 days, the mean numbers of BrdU-labelled epithelial cells were significantly lower in the weaned piglets than in their unweaned counterparts (Fig. 4). However, at the ages of 28 and 31 days, the difference was opposite. The increased mitotic activity at days 4 and 7 after weaning, fits into the concept of hyper-regeneration following villus atrophy. It also supports the suggestion of Xxxxxx et al. (1997) that cell-kinetic changes after weaning are similar to those described in starvation followed by re-feeding, which caused a decreased cell production rate in the crypts followed by an increase (reviewed by Pluske et al. 1997). As stated in the introduction, the increased mitotic activity at days 4 and 7 after weaning can explain the increased susceptibility of the piglet to diarrhoea and growth depression in the post-weaning period.

Xxxx and Xxxxx (1989), using the vincristine technique that arrests dividing cells in metaphase, found that there was less mitotic activity in crypts at 3 days after weaning and suggested that this induced shorter villi rather than villus damage. This suggestion agrees with our findings in that there was a positive relationship between mitotic activity and villus length at day 2 after weaning (Fig 5).

At day 7 after weaning, the SDPP-fed piglets showed less mitotic activity than did the piglets receiving the casein diet, but the difference only reached statistical significance for the site at 25% of the length of the small intestine. When the BrdU data of days 4 and 7 after weaning were combined and were adjusted for sow and age, the comparison of SDPP-fed with casein-fed piglets showed for the former significantly less mitotic activity in epithelial cells at the site at 25% of the length of the small intestine. A similar, but non-significant effect at day eight after weaning in the proximal jejunum was reported by Xxxxx et al. (2000). The mechanism by which SDPP may affect mitotic activity is not known. There could have been secondary effects on mitotic activity, such as effects mediated by changes in the intestinal microflora. As explained above, higher mitotic activity predisposes to disease (Xxxxxxx et al. 1994). The lower mitotic activity in piglets

fed SDPP might explain the better health and performance found in most investigations on SDPP feeding in weaned piglets (Xxx Xxxx et al. 2001).

Acknowledgements

This research was supported by the Fund BTS from the Dutch Ministry of Economic Affairs.

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Xxxxxxx, J.D., Xxxxxxxxx, K.J., Xxx, X., Xxxxx, G.L., Xxxxxxx, N.D., Xxxxx, M.S., Xxxx, L.W., 1997. Effect of spray-dried plasma and fructooligosaccharide on nursery performance and small intestinal morphology of weaned pigs. J. Anim. Sci. 75: suppl.1., 199 (abstr.).

Xxxxxxxxx, K.J., Xxxxx, G.L., Xxxxxxx, M.D., Xxxx, L.W., Xxxxxxxxxx, M.R., 1997. Impact of feed intake and spray-dried plasma on nursery performance and intestinal morphology of weaned pigs. J. Anim. Sci 75: suppl.1., 198 (abstr.).

Xxx Xxxxx-Xxxxxxxx, H.M.G., Xxxxxxx, M.J.A., Xxxxxxxx, X., Kalsbeek-Van Der Valk, H.J.L., Xxxxxxx, TH., Xxxxxxxx, X.X., 1998. Weaning and the weaning diet influence the villous height and crypt depth in the small intestine of pigs and alter the concentrations of short-chain fatty acids in the large intestine and blood. J. Nutr. 128: 947-953.

Van Beers-Schreurs, H. M. G., Xxxxxxxx, X., Xxxxxxx TH., Xxxxxxxx, H.J., 1992. The pathogenesis of the post weaning syndrome in weaned pigs; a review. Vet. Quart. 14: 29-34.

Van Der Peet-Xxxxxxxxx, C.M.C., Xxxxxxxxxx, G.P., 1995. The effect of spray-dried porcine plasma in diets with different protein sources on the performance of weanling piglets. Report P1.137. Praktijkonderzoek varkenshouderij. Rosmalen. The Netherlands.

Xxx Xxxx, A.J., Xxxxxx, X., Xxxxxxx, M.J.A., Xxxxxx, R.J.C.F., Xxxxxx, A.C., 2001. Growth performance of weanling pigs fed spray-dried animal plasma: a review. Livest. Prod. Sci. 68: 263-274.

Xxxx, X.X., Xxxxxx, X., 1992. Alterations in quantitative distribution of Na, K- ATPase activity along crypt-villus axis in animal model of malabsorption characterised by hyperproliferative crypt cytokinetics. Dig. Dis. Sci. 37: 417-425.

Xxxxxxx-Xxxxxx, X., Xxxxxxxx X.X., 1986. Use of bromodeoxyuridine for cell kinetic studies in intact animals. Cell tissue kinetics 19: 179-182.

CHAPTER 4.2

Small intestinal morphology and disaccharidase activities in early-weaned

PIGLETS FED A DIET CONTAINING SPRAY-DRIED PORCINE PLASMA

A.J. Xxx Xxxx0, T.A. Niewold2 M.J.A. Nabuurs2, X. Van Hees1, P. De Bot1, N. Stockhofe-Zurwieden2, X. Xxxxxx-Blanksma1 and A.C. Beynen3

1 Co-operative Central Laboratory “CCL-Nutricontrol” of Cehave Landbouwbelang, X.X. Xxx 000, 0000 XX Xxxxxx, Xxx Xxxxxxxxxxx,

2Department of Immunology, Pathobiology and Epidemiology, Institute for Animal Science and Health, ID-Lelystad, X.X. Xxx 00, 0000 XX Xxxxxxxx, Xxx Xxxxxxxxxxx,

3Department of Nutrition, Utrecht University, Faculty of Xxxxxxxxxx Xxxxxxxx,

X.X. Xxx 00000, 0000 XX Xxxxxxx, Xxx Xxxxxxxxxxx

Journal of Veterinary Medicine, Series A (accepted for publication)

Abstract

The goal of this study was to test whether dietary spray-dried porcine plasma (SDPP) in early-weaned piglets prevents small intestinal villus atrophy by trophic or protective activity. Fifty-four weaned, 18-days old piglets were used to determine the effect of dietary SDPP on small intestinal villus length, crypt depth, enterocyt mitotic activity and brush border enzyme activities during the first week after weaning. The piglets were offered a diet containing either 8% SDPP or 8% casein.

At 2 and 7 days after weaning, piglets were anaesthetised to provide samples of the small intestinal wall and killed immediately afterwards. There were no differences in daily gain and daily feed intake between the two dietary treatments. At day 2 after weaning, all piglets showed a marked reduction in villus height when compared with baseline values. In all piglets, small intestinal enterocyte mitotic activity had decreased by day two and was increased again on day 7. There were no significant effects of dietary SDPP on small intestinal villus length, crypt depth and enterocyt mitotic activity. This indicates that SDPP has no trophic effect on the small intestinal mucosa and that it does not protect against the damaging effect on the small intestinal villi that is associated with the process of weaning. There was no effect of SDPP on lactase, sucrase or maltase specific activities that are a measure of the digestive function of the small intestine. It can be concluded that SDPP versus casein has no effect on small intestinal morphology and disaccharidase activities in early-weaned piglets kept under low infection pressure.

Introduction

In piglets, the process of weaning is associated with small intestinal villus atrophy (Hall and Xxxxx, 1989), which impairs digestive and absorptive function of the gut (Hampson and Kidder 1986, Nabuurs et al. 1994, Xxxxxx et al. 1997). The addition of spray-dried animal plasma (SDAP) to diets of weaned piglets generally has a positive effect on average daily feed intake (ADFI) and average daily gain (ADG) (Xxx Xxxx et al. 2001a) and may diminish the incidence of diarrhoea (Gatnau 1990, Van der Peet-Xxxxxxxxx and Binnendijk 1995).

So far, the mode of action of SDAP remains obscure. Xxx Xxxx et al. (2001b) investigated the effects of dietary spray-dried porcine plasma (SDPP) versus casein on small intestinal morphology and enterocyt mitotic activity in piglets that were weaned at 24 days of age. There was no significant effect of dietary SDPP on villus length or crypt depth, but the SDPP-fed piglets tended to have less mitotic activity. Similar results have been reported by Xxxxx et al. (2000). Xxx Xxxx et al. (2001b) found an increased mitotic activity at days 4 and 7 after weaning in weaned versus unweaned piglets. An increased mitotic activity results in more immature enterocytes (Xxxx and Xxxxxx 1992), leading to an impaired digestive and absorptive function (Xxxxxxx et al. 1983, Xxxxx 1984, Xxxxx 1985, Xxxx and Xxxxxx 1992) and increased sensitivity to bacterial toxins and increased toxin migration through the enterocyte membrane (Xxxxxx et al. 1991, Xxx and Xxxxxx 1993, Nabuurs et al. 1994). As suggested by Xxxxxxx (1986) and Xxxxxxx et al. (1994), these effects explain the increased susceptibility of the piglet to diarrhoea and growth depression in the post-weaning period. Less mitotic activity is associated with less immature enterocytes, which might explain the beneficial effects of SDPP (Xxx Xxxx et al. 2001b). It could be suggested that weaning at an

Small intestinal morphology and disaccharidase activities in early-weaned 93

PIGLETS FED A DIET CONTAINING SPRAY-DRIED PORCINE PLASMA

earlier age than in our previous experiment (Xxx Xxxx et al. 2001b) would result in more pronounced effects of SDPP because weaning-induced morphological changes in the small intestine are more conspicuous when weaning occurs at an earlier age (Pluske et al. 1997). The objective of the present study was to determine the effect of dietary SDPP on villus length, crypt depth and enterocyt mitotic activity of piglets that were weaned at the age of 18 days. The specific activity of brush-border (BB) enzymes is a measure of the digestive function of the small intestine (Xxxxx 1985, Pluske et al. 1997). Immature enterocytes have a lower BB enzyme activity than older enterocytes (Xxxxx 1985). The effect of SDPP, if any, on the activity of the BB enzymes lactase, sucrase and maltase was unknown, which prompted us to determine these activities also.

Materials and methods

Animals and design

Animal care and use. The experimental design was approved by the Animal Experiments Committee of ID-Lelystad.

Fifty-four piglets from the closed herd of the research station ‘Laverdonk’, Veghel were used. The piglets (F2 cross-bred: GY x [Finnish X Dutch Landrace]) were females and castrates aged 18 d with an average weight of 6.3 kg. The experiment had a complete randomised block design with each block consisting of 8 piglets from the same litter. At the age of 18 days, the piglets of 6 sows were weaned and assigned randomly to one of two treatments. The piglets were offered a diet containing either SDPP (4 piglets per litter) or casein (4 piglets per litter). To obtain baseline values, at the age of 18 days, one randomly chosen piglet from each litter was anaesthetised to provide samples of the small intestinal wall and was killed immediately afterwards. From each treatment group, two randomly chosen piglets from each sow were sampled and killed at 2 and 7 days after weaning. As a result, there were 24 piglets for each feeding treatment.

Housing Environments. The piglets that had been weaned were penned in individual cages (1.2 m x 0.42 m) with slatted metal floors. The cages were placed in an environmentally regulated room. The piglets had free access to feed and water. Each pen was equipped with a water nipple and a one-hole self-feeder. The room temperature was 26 oC. No creep feed was provided during the lactation period.

Feeding. The composition of the experimental diets is shown in Table 1. The diets, which were in pellet form, contained either 8% (w/w) casein or SDPP. The diets were formulated to contain 1.3 % apparent ileal digestible lysine and 2352 kcal NE/kg. Pelleting temperatures were kept low (65 oC and 67 oC for the control and

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SPRAY-DRIED ANIMAL PLASMA IN THE DIET OF WEANLING PIGLETS: INFLUENCE ON GROWTH PERFORMANCE AND UNDERLYING MECHANISMS

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