Animal Feed Science and Technology, 24 (1989) 267-274 267 Elsevier Science Publishers B.V., Amsterdam - - Printed in The Netherlands

Evaluat ion of Pea Prote in Concentrate as a Source of Prote in in Mi lk Rep lacers for Hols te in Calves

P.K. MBUGI, J.R. INGALLS and H.R. SHARMA

Department of Animal Science, University of Manitoba, Winnipeg, Man. R3T 2N2 (Canada)

(Received 5 May 1987; accepted for publication 26 August 1988)

ABSTRACT

Mbugi, P.K., Ingalls, J.R. and Sharma, H.R., 1989. Evaluation of pea protein concentrate as a source of protein in milk replacers for Holstein calves. Anita. Feed Sci. Technol., 24: 267-274.

Thirty pre-ruminant Holstein calves (six males+four females per treatment) were fed three milk replacer diets during the pre-weaning period of 45 days. The control diet (1) was based on skim milk powder as the major source of protein. The test diets (2 and 3) were formulated to contain, on a dry matter (DM) basis, 8.25 and 16.5% pea protein concentrate (PPC) which supplied 30 and 60% of total dietary protein, respectively. These diets were also supplemented with DL-methionine at ~ 2% of the PPC. Calves were weighed at birth, Day 4 and once a week throughout the experimental period.

Average daily gains during 0-45 days of age were significantly higher for calves receiving the control milk replacer diet than those given the diet containing 60% protein from PPC and slightly, but insignificantly (P>0.05), higher than those fed the lower level of PPC diet. The apparent digestibility of DM, crude protein (CP) and energy were significantly lower for the milk replacer diet containing 60 % protein from PPC than the all-milk protein diet (control) and were similar to that of Diet 2 containing 30% protein from PPC. The digestion coefficient of ether extract (fat) was not significantly different among the three dietary treatments; however, there was a trend for lower fat digestion by the calves receiving the milk replacer containing the highest level of PPC.

The data from the present studies indicate that PPC (80% CP) could supply 30% of the protein in milk replacer diets for Holstein calves without markedly affecting the utilization of nutrients and growth performance of pre-ruminant calves. PPC at 60% of the dietary protein appeared to depress the nutrient digestibility and growth of young calves.

INTRODUCTION

In te res t has been ma in t a ined in the rep lacement of cost ly milk pro te in in the diets of p r e - r u m i n a n t calves by a l te rna t ive sources of protein. A t t e m p t s to incorpora te vegetable pro te ins in milk replacers have only been par t ia l ly suc- cessful for ut i l izat ion by p r e - r u m i n a n t calves due to the i r relative inabil i ty to digest such pro te ins (Gorri l l et al., 1976; Roy et al,. 1977; Bell et al., 1979; Wi t t enbe rg and Ingalls, 1979). Bell and co-workers (1974) repor ted tha t pea

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protein used at 50% in the milk replacer for young calves was 25% digestible by calves < 2 weeks of age and 65-70% digestible at 3 weeks of age. Similarly, Wittenberg and Ingalls (1979) reported that faba-bean protein in the milk replacers of Holstein calves was 57% digestible at 1-2 weeks of age and 80% digestible at 3-4 weeks of age.

Reduced body weight gains and decreased dry matter (DM) and crude pro- tein (CP) digestibilities have been observed with increased levels of soya-bean protein in milk replacers for young calves (Nitsan et al., 1971; Akinyele and Harshbarger, 1983). Gorrill et al. (1976) indicated that rapeseed protein con- centrate could supply at least 30% of the protein in milk replacers and this level of rapeseed protein concentrate did not affect the utilization of nutrients in milk replacers and growth of calves after 1 week of age.

Like the other leguminous seeds, pea protein is also deficient in methionine, though rich in cystine and arginine (Bell and Youngs, 1970). Supplementation of pea protein concentrate (PPC) with methionine in the diet of mice resulted in a feed efficiency similar to those obtained with fish protein concentrate, casein or egg protein.

The objective of this experiment was to determine the effect of replacing part of skim milk protein with PPC at two levels in milk replacer diets on calf performance from birth to weaning at 6 weeks and on the apparent digestibility of various nutrients in the milk replacer diets.

MATERIALS AND METHODS

Three milk replacer diets were formulated to contain ~ 22% CP and 17% fat (Table 1). Milk replacer Diet 1 was based on skim milk powder as a major source of protein and used as a control diet for this study. Diets 2 and 3 were formulated to contain 8.25 and 16.5% of DM as PPC, respectively, which sup- plied 30 and 60% of the total dietary protein. These diets were also supple- mented with DL-methionine at ~ 2% of PPC.

Holstein calves of both sexes were randomly assigned to one of the three replacer diets as they were available from the University dairy herd. Care was taken to allot at least six male and four female calves to each of the dietary treatments for balancing the sexes. Calves were kept with their dams for 12- 24 h and then placed in individual pens bedded with wood shavings. Colostrum from the dams was fed during Days 2 and 3 at 10% of body weight, and at 5% for Days 4 and 5 plus 250 g milk replacer. The experimental period started from Day 4 and continued to 45 days of age.

Milk replacers were reconstituted with warm water at the ratio of I part dry powder to 6 parts water in the respective containers and mixed with a stirrer to prevent settling of the dry powder at the bottom. The liquid diet contained ~ 14.3% solids and was fed twice daily as the sole source of nutrients during the experimental period. Milk replacer was gradually increased from 500 g at

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TABLE1

Ingredients and chemical composition of milk replacer diets containing different levels of pea protein concentrate (PPC)

Dietary treatment 4

0% PPC 30% PPC 60% PPC (control)

Ingredient (% DM) Ho milk 1 powder 30.00 30.00 30.00 Skim milk powder 55.43 34.40 13.40 Dried whey powder 9.19 10.82 13.32 PPC 2 8.25 16.50 DL-methionine 0.15 0.30 Dextrose 10.30 18.50 Vitamin pre-mix 3 5.18 4.88 5.28 Dicalcium phosphate 1.00 2.50 Chromic oxide 0.20 0.20 0.20

Chemical composition (% DM) CP 23.4 22.8 22.5 Ether extract 17.7 17.5 17.8 Gross energy (MJ g-l) 20.4 20.5 20.3

~Commercial milk replacer product containing 60% choice white grease plus whey and lecithin. 2A product of Woodstone Foods Ltd., Portage la Prairie, Man., Canada, containing 80% CP on a DM basis. :~Commercial milk replacer, vitamin trace minerals and salt pre-mix. 4Amounts of dry milk replacers used during days 4-45 were: 4-5, 200 g; 6-10, 500 g; 11-17, 600 g; 18-28, 700 g; 29-31,800 g; 32-38, 900 g and 39-45, 1.00 kg per day, respectively.

6 days of age to 1000 g at 39 days or 30.5 kg in total . Wa te r was available free choice to the young calves in the i r individual pens. Calves were weighed im- media te ly at b i r th , t h e n on Day 4 for init ial body weight and once a week t h r o u g h o u t the expe r imen ta l period. Final weight was t ak en on Day 45 for all calves.

T h e a p p a r e n t digest ibi l i ty of the d ie ta ry nu t r i en t s of the th ree milk replacers was de t e r mine d wi th male calves only. C h r o m i u m oxide (0.2%) was mixed in the milk replacer diets and used as a m a r k e r for ca lcula t ing the ap p a ren t di- gest ibi l i ty of nu t r ien ts . Faecal samples were col lected f rom the male calves twice daily for six days f rom 18 to 28 days of age. Faecal samples f rom each calf were compos i t ed separa te ly a f te r the col lect ion per iod for subsampl ing and de t e r mina t i on of DM.

Chemical analysis

Milk replacer samples and faecal samples were dr ied at 65 °C for 60 h in a forced air oven to cons t an t weight for the d e t e r m i n a t i o n of DM. Dr ied faecal

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samples were ground through a 1-mm screen and stored for chemical analysis of chromium oxide, CP, gross energy and fat as ether extract. Analyses of the milk replacers and faecal samples were determined by following the standard Association of Official Analytical Chemists (1984) procedures. Chromium ox- ide was analysed by the method of Williams et al. ( 1962 ).

Statistical analysis

Data of this study were subjected to analysis of variance following the gen- eral linear models of the Statistical Analysis Systems (1985) procedure. Least square means of the treatments with respective standard errors are reported in Table 2 below.

RESULTS AND DISCUSSION

Milk replacer diets (2 and 3) containing PPC were less readily accepted by the young calves in the first week of feeding compared to the consumption of the skim milk replacer (control) diet. One calf on Treatment 2 developed acute scours and was withdrawn from the test. Three more calves on Treatment 2 developed scours, were off feed for a day or two and were successfully treated with penicillin. Three calves on Treatment 3 also went off feed for a day or two and then consumed their liquid diet without any difficulty; two of these calves had scours. Intake by these calves varied from no replacer for a day and half of the feed the next day to a day or two with reduced intake.

Average daily gains were not significantly (P> 0.05) different among the three treatments during 0-24 and 25-45 days of age (Table 2 ). However, calves receiving milk replacer containing 60% protein from PPC tended to gain ~ 25- 27% less body weight compared to those fed with Milk Replacer Diets 2 and the control during 0-24 days of age and 20-30% during 25-45 days of age, respectively. Average daily gains during 0-45 days of age were significantly higher ( P < 0.05) for the calves receiving the control milk replacer diet than those calves fed the diet containing 60% protein from PPC and similar to the group given the low level of PPC milk replacer diet (Fig. 1 ). Bell et al. (1979) observed no differences (P>0.05) in the growth rate of calves, during 3-14 days of age, receiving the milk replacer diets containing different levels (0, 25, 50 and 75% ) of dietary protein from pea flour. Although the gains were poor for all the four groups, weight gains were significantly lower for calves fed the highest level of pea protein in the milk replacer during 21-35 days of age as compared to the control and the other two milk replacers containing 25 and 50% pea protein. Pre-starter pellets were also fed to the calves along with the milk replacer diets in their studies, whereas no other feed was offered to the calves in the present experiment. Gorrill et al. {1976) reported that heifer calves fed a milk replacer containing 60% of the protein from rapeseed protein concentrate gained significantly ( P < 0.05) less body weight to weaning than

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TABLE 2

Least square means with standard errors for average daily gains and apparent digestibility of nutrients of three milk replacer diets fed to young Holstein calves

Dietary t reatment

0% PPC 30% PPC 60% PPC (control)

Average daily gain (g per day) 0-24 262 ± 36 256 ± 36 192 ± 41

25-45 701 ± 59 617 ± 54 492 ± 63 0-45 478 a ± 26 421 "b -+ 24 358 b ± 26

Apparent digestibility of nutrients (%) DM 92.1 a ± 1.0 CP 87.6 a ± 1.8 Energy 92.0" -+ 1.22 Ether extract 91.6 ± 2.8

91.24± 1.1 87.1b± 1.1 85.9" ± 1.9 78.7b ± 1.9 91.4"--+ 1.3 86.55± 1.3 91.0±3.1 84.5_+3.1

a'bMeans with different superscripts are significant (P < 0.05 ).

8 0 -

70

60

5O 0 aD

4 0

30

o o Y = 3 7 . 3 4 3 + 0 . 5 3 7 X

a , - - - - - a Y = 3 7 . 1 1 9 + O . 4 9 9 X

~ Y ~ 3 6 4 4 6 + 0 . 4 1 8 X

o

o

D

o o

O O O

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oo o ao ~ i~/~

. o o /o . ooo

4 t o - / " o o . .

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, , i i I i I J I I , i , i i i , i i i , , , , , i i , , i , , , , , i , I , 1 , I , i i I , , i I

0 I O 20 30 40 5 0

A G E ( D A Y S )

Fig. 1. Body-weight change of calves receiving milk replacers with 0% ( - - ) , 30% (- - -) or 60% (- - ) of the protein as pea protein.

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those calves fed the all-milk protein replacer. There was, however, compen- satory growth of the heifer calves between weaning and 12 months of age which eliminated the pre-weaning growth effects of high rape protein concentrate in milk replacer. Wittenberg and Ingalls (1979) did not observe any significant differences in the average daily gains of calves when faba-bean protein concen- trate provided 0, 25, 50 and 80% of the dietary protein in the milk replacers fed to Holstein calves. The growth of calves receiving the PPC milk replacers in the present studies during the pre-weaning period was within reasonable limits recommended for the young Holstein calves.

Digestion coefficients of DM, CP and energy were significantly lower (P<0.05) for the milk replacer containing 60% protein from PPC than the all-milk protein milk replacer (control) or the milk replacer containing 30% protein from PPC (Table 2). The apparent digestibility of ether extract was not significantly (P> 0.05 ) different among the three replacers; however, there was a trend for lower fat digestion by the calves receiving the milk replacer containing 60% protein from PPC. The depression in apparent digestibility of DM and energy could be associated with the reduction in the digestion of veg- etable protein from PPC as compared to milk protein.

Lower digestibilities of DM, organic matter, CP and ether extract associated with poorer growth rate and inferior feed efficiency were also observed by Silva et al. (1986) for the calves receiving milk replacers containing 66% protein from soya bean sources compared with those fed the 100% milk protein milk replacer. The poorer growth of calves receiving the milk replacer diets contain- ing vegetable proteins could be associated with the decreased ability to absorb nutrients in the small intestine of young calves (Seegraber et a1.,1979).

Christinson (1980) substituted 50% of the milk protein in the milk replacers of calves with 50% PPC containing ~ 53% CP. Before incorporation into the milk replacers, PPC was; (1) slurried in water and roll dried; (2) slurried in water + CaO and then roll dried; (3) extruded; (4) added as isolated pea pro- tein (93% CP); (5) added as untreated pea protein concentrate as a control for these treatments. The results indicated that untreated pea protein was vir- tually indigestible by young calves, but the various treatments to the PPC markedly improved CP digestibility. The digestibility of the PPC increased with the age of the calf, although untreated material was better digested by a 17-day-old piglet than a 43-day-old pre-ruminant calf.

Reduced apparent digestibilities of DM, CP, energy and fat of the milk re- placer diets containing 60% protein from PPC resulted in poorer growth per- formance of young Holstein calves compared with the control group fed all- milk protein milk replacer. These results are similar to those obtained by Bell et al. (1974) and Christinson (1980). The type of PPC used by Bell et al. (1974) was prepared by hydrolysis of pea flour with enzyme to remove the starch and contained ~ 60% CP on a DM basis, PPC used by Christinson (1980) was prepared by air classification and contained ~ 53% CP, whereas PPC used

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in the present studies contained ~ 80% CP. Pea protein is separated using a wet slurry method with lowered pH to separate the protein from fibre and starch. The isolate is spray dried. Vegetable proteins in milk replacer diets fail to produce normal coagulum, escape pre-digestion by the calf's stomach en- zymes and quickly flow into the small intestine, which tends to promote the proliferation of pathogenic bacteria in the upper part of the small intestine. This might predispose the calves to scouring. There tended to be more scouring with calves receiving the PPC.

The results of the present studies indicate that PPC (80% CP ) could supply at least 30% of the protein in milk replacer diets of Holstein calves without markedly affecting the utilization of nutrients or growth performance of the pre-ruminant calves. Substitution of milk protein with 60% of protein from pea protein source appears to depress the digestibility of nutrients and growth of young calves.

ACKNOWLEDGEMENTS

The authors gratefully acknowledge the Canadian International Develop- ment Agency for financial assistance to the senior author, Woodstone Foods Ltd., Portage la Prairie, Man., for supplying pea protein concentrate, dairy barn personnel of Glenlea Research Station for the care of the animals and Terri Garner for technical assistance.

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