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North Carolina State University Return
to main menu Vegetable Proteins Sources for Diets of
Suckling Pigs A. Ebert, A. Berman, B. Harrell, S. Cornelius1 and J. Odle 1Milk Specialties, Dundee IL Summary Technologies to rear suckling piglets apart from the sow recently have been implemented on large commercial farms, and success has been measured in both accelerated growth and in reduced pre-weaning mortality. However, diets formulated with cow-milk proteins can be cost-prohibitive. This experiment compared the replacement of whey protein (WHEY) with isolated soy protein (ISP), a hydrolyzed vegetable protein blend (HYDROL) or the latter in combination with whey protein (WHEY/HYDROL) in liquid diets fed to neonatal pigs from two to 19d of age. Pigs were housed individually in an environmentally controlled room and were offered the liquid diets ad libitum via a gravity-flow feeding device. On d 19, pigs fed the vegetable-protein diets weighed 20% more (8,179 ± 211 g, P <0.05) than pigs fed the WHEY diet (6,805 ± 244 g). The ADG was 35% higher for pigs fed the HYDROL diet than for pigs fed the WHEY diet. Similarly, ADFI was greater for WHEY/HYDROL and HYDROL diets compared to the WHEY diet, (P < 0.05). Overall, pigs fed the HYDROL diet had a 16% higher G/F than pigs fed the WHEY diet. These results are likely related to a poorer balance of amino acids (especially arginine) within the WHEY diet. Collectively, these data support the conclusion that both the hydrolyzed vegetable protein blend protein and isolated soy protein are good alternatives to whey protein in liquid diets formulated for neonatal pigs and that an appropriate balance of amino acids is more important than the source of protein per se. Introduction According to recent swine production statistics from the US Department of Agriculture (USDA, 2000), pre-weaning piglet mortalities resulting from crushing and starvation account for more than 70% of piglet deaths during the lactation period. Adding to this are convincing data showing that milk yield of sows is not sufficient to support maximal suckling piglet growth (Harrell et al., 1993; Zijlstra et al., 1996b). Indeed, Azain et al. (1996) demonstrated a clear benefit of supplemental milk replacer during lactation to increase weaning weight, especially when sows are under heat stress. However, the potential economic benefits of milk-feeding technology must be evaluated against special equipment costs and the relatively high cost of typical liquid-diets utilizing expensive milk-based ingredients (Odle and Harrell, 1998, 2001). Several alternative ingredients have been evaluated as complete or partial replacments for milk-based ingredients. In terms of protein, soybean meal, isolated soybean protein (ISP; Mateo and Veum, 1980), hydrolyzed soybean proteins (Zijlstra et al. 1996a) and wheat gluten (Chae et al., 1999) have been the more common alternatives. Overall, the use of vegetable proteins usually results in lower growth performance for young pigs (< 14 d old). Poor performance has been explained by a temporary enzymatic limitation to digest vegetable nutrient sources and a transient intestinal hypersensitivity to soy proteins (glycinin and b-conglycin) in young pigs (Li et al. 1990). However, McCracken et al. (1998) observed that neither intact nor hydrolyzed soy proteins elicit intestinal inflammation in neonatal pigs. Similarly, Moughan et al. (1990) reported no difference in digestive enzyme activity in pigs fed ISP or bovine milk protein based diets. Therefore, the objective of this experiment was to evaluate the partial replacement of milk protein by a hydrolyzed soybean/wheat protein in liquid diets fed to pigs from 2-19d of age. Materials and Methods Animals and diets. Animal procedures were approved by the Institutional Animal Care and Use Committee of North Carolina State University. A total of 66 crossbred (PIC genetics) two-d-old, mixed-gender piglets averaging 1.8 kg in weight, were drawn from eight litters (supplied by Murphy Family Farms, Magnolia, NC). The experiment was conduced in two replicates. In each replicate, six pigs were used for initial body composition and intestinal measurements and six pigs were randomly assigned to each treatment/diet and housed individually in cages within an environmentally controlled room (32oC, see photo 1). During the first 8-12 hr of the experiment, pigs were trained to consume liquid diet as it was manually dispensed through a nipple. This process was repeated at one to two hr intervals for every pig until they had learned to freely suckle from the apparatus. After training, a gravity-flow feeding system (McClead et al., 1990) was employed which consisted of a two-liter plastic bottle placed over the cage with a tube connecting the bottle to a nipple attached to the cage. In order to keep the semi-soluble ingredients in uniform suspension, a stir plate was used under each bottle (photo 1). Diets were reconstituted to a concentration of 15% solids on a daily basis and kept refrigerated at 4oC until feeding. Fresh liquid diet was added to the bottles four times a day (at 8:00, 13:00, 18:00 and 23:00 h) to ensure that pigs had ad libitum access to fresh feed. Unconsumed milk was measured and discarded, and all components of the feeding system were cleaned twice a day (at 8:00 and 13:00 h feedings). Pig weights and diarrhea scores were recorded daily prior the first feeding (8:00). The experiment was continued until pigs reached 19d of age. Diets were prepared by the Milk Specialties Co. (Dundee, IL) as dry powered formulas, differing primarily in source of protein. In the first replicate, four diets were utilized as follows: 1) A positive control diet with whey as only protein source (WHEY), 2) whey protein partially replaced (41%) by a hydrolyzed vegetable protein blend (WHEY/HYDROL), 3) whey protein partially replaced (77%) by the hydrolyzed vegetable protein product (HYDROL) and 4) a negative control diet with whey protein partially replaced (63 %) by isolated soy protein (ISP). Because the growth performance of pigs fed the positive control (WHEY) diet was lower than those fed the test diets in the first replicate, a fifth diet was included in the second replicate of the experiment. In the new diet (CASEIN), the 47% of the whey protein was replaced by casein. The data from this fifth diet were only used as a reference value for our first positive control diet and were not include in the statistical analyses. Diets were formulated (Table 1) to contain similar metabolizable energy and total lysine levels (1.94%) and to exceed the NRC requirements for pigs from 3 to 5 kg (NRC, 1998). Plasma urea nitrogen. After collection on day 19, blood samples were centrifuged (Beckman, model J-B6) at 824 x g for 10 min, and plasma collected and frozen at -20oC until further analysis. Plasma was analyzed for urea nitrogen (PUN) by the quantitative urease/Berthelot procedure (Sigma Diagnostics, St. Luis, MO) based on methods described by Fawcett and Scott (1960) and Chaney and Marbach (1962). Statistical analyses. Pigs were randomized to treatments according to ancestry and initial body weight, without regard to gender. Pig was considered the experimental unit. The effects of dietary protein were assessed by analysis of variance, and treatment means were separated using Tukey’s test. The experimental replicate was included in the model but not reported because there was no interaction with dietary treatments. For growth performance variables, initial body weight was included in the model as a covariable, and the reported values are the least square (covariate-adjusted) means; otherwise, the reported values are the arithmetic means. Two pigs were excluded from the trial because they developed severe diarrhea and very low feed intake, and data from pigs fed the CASEIN diet (in replicate two) were not included in statistical analyses. All data were subjected to variance analysis using the GLM procedure of SAS (SAS Inst. Inc., Cary, NC). Means were considered different when P < 0.05. ResultsGrowth performance. On day 9, pigs fed the HYDROL diet were already 25% heavier than pigs fed the WHEY diet and 12% heavier than pigs fed the WHEY/HYDROL diet (Table 2). There were no differences between the HYDROL and ISP or between the ISP and WHEY/HYDROL diets. On days 16 and 19 pigs fed the WHEY diet weighed only 83% of pigs fed the other diets (Table 2). The body weights of pigs fed the CASEIN diet (in the second replicate) were similar to those fed the WHEY diet: 3,166, 5,874 and 7,265 g respectively on days 9, 16 and 19. Overall, pigs fed the WHEY diet gained 100 g/d less than pigs fed the HYDROL diet. During the first week of the experiment, pigs fed the HYDROL diet gained 60% more than pigs fed the WHEY and 25% more than pigs fed the WHEY/HYDROL diet. Even pigs fed the ISP diet had 20% greater ADG than those fed the WHEY diet. There were no differences between HYDROL and ISP diets or between WHEY and WHEY/HYDROL diets. Likewise, during the second week, pigs fed the WHEY diet gained more slowly than pigs fed all other diets. The overall (d2-19) ADG for pigs fed the CASEIN diet (305 g/d) was similar in magnitude to those fed the WHEY diet (291 g/d). Average daily feed intake (ADFI; dry matter basis) during the first week was 25% greater for pigs fed the HYDROL diet than those fed the WHEY diet. During the second week, pigs fed the ISP diet showed a 23% greater ADFI than pigs consuming the WHEY diet. Overall, animals fed either the ISP or HYDROL diet had higher (~22%) ADFI than those fed the WHEY diet. Pigs fed the CASEIN diet consumed on average 283 g DM/d (data not shown). During the first week, pigs fed the WHEY diet were about 20% less efficient (G/F) than pigs fed other diets. There were no detected differences in efficiency of gain during the second week, but overall, the HYDROL diet promoted a 16% greater G/F than the WHEY diet. Concentration of plasma urea nitrogen (PUN, table 3) was lowest in pigs fed the WHEY diet. Discussion The overall average daily gain (ADG) during the 17 day test period was 358 ± 12 g/d, which is similar to that observed in other artificial-rearing pig experiments (Jones et al., 1977; Kim et al., 2001; Oliver et al., 2002) and greater than that observed in non supplemented natural sow-reared pigs (i.e., approximately 130% greater than the ADG reported by Azain et al., (1996) and 180% greater than data reported by Wolter et al. (2002) for similar-aged pigs). The poorest
performance exhibited by pigs fed the WHEY diet cannot be completely explain
by the lower ADFI because the feed efficiency (G/F) also was lower for the
WHEY compared with the HYDROL diet.
Apparently there is a contradiction between this result and the
traditional knowledge which assumes that newborn piglets have unique
nutritional needs that include high-quality sources of nutrients, especially
proteins, with milk-based proteins being considered of very high quality. Mateo and Veum (1980) reported a decline of
approximately 50% in ADG of pigs fed an ISP based diet compared to piglets
fed a dried-skim-milk or casein-based diet from 1-15 d of age, but no
differences were observed in pig performance from 15-29 d of age. Newport (1980) observed no effect
on pig performance from 2-28 d of age with partial replacement of dried skim
milk by a mixture of ISP and dried whey when soy protein provided 37% of
dietary protein. However, very poor
growth was observed when soybean protein provided 74% of dietary protein,
with only four out of 21 pigs
surviving. This mortality was related to severe diarrhea. Jones et al. (1977) reported no
significant effect on pig performance when 25% of non fat dried milk was
replaced by soy flour as protein source in a liquid diet fed to pigs from
21-36 d of age. McCracken et al.
(1998) reported an intermediate ADG for baby pigs fed a hydrolyzed soybean
protein based diet (109 g/d) compared with a casein/whey (121 g/d) and an
intact soy protein based diet (85 g/d) from 7-17 d of age. Sohn et al, 1994a, tested isolated and
concentrated soy proteins, dried skim milk and soybean meal as protein
sources in diets for pigs from 21-35 d of age. In that study, isolated and concentrated soy proteins provided
similar average daily gains as dried skim milk and higher gains than soybean
meal based diets. From these studies,
it seems clear that the response to
inclusion of a vegetable protein source depends on the percentage of
inclusion, how it is processed and the age of the pigs. Indeed, the improved efficiency of
utilization of vegetable proteins has been attributed to an adaptation of the
digestive enzyme system of the pigs to the protein sources that occurs with
age (Kidder and Manners, 1980).
Nonetheless, we found no
literature showing better performance for any vegetable-protein
compared with milk-protein-based diets fed to such young pigs as we report in
this experiment. On average, total lysine per unit of metabolized energy in our diets was 4.3g of total lysine per Mcal of ME, which is slightly below NRC (1988) recommendations for pigs from 3 to 5 kg (4.5g lysine/Mcal ME) and much lower than that used by Oliver et al. (2002) (6.2 g of total lysine/Mcal ME). However the lysine/ME ratio among the diets used in this experiment did not change significantly: 3.5, 3.5 and 3.3g of apparent ileal digestible lysine/Mcal ME for WHEY, HYDROL and ISP diets, respectively. So the differences among treatments are much more likely related to an unbalance of some amino acids (other than lysine) rather than the source of protein per se. An amino acid imbalance may result when diets are supplemented with one or more amino acids other than the limiting amino acid. A reduction in feed intake is common in most of these situations (NRC, 1998). Manufactured milk replacers can be especially subject to this unbalance because amino acid requirements are not yet well established for very young pigs, consuming liquid diets. For example, one of the amino acids that had the highest variation among the experimental diets and higher difference in daily intake was arginine. Total arginine level in sow’s milk is 1.37% (Mavromichalis et al., 2001), about 65% of the lysine level in the milk, while the NRC (1988) suggests an arginine level of 40% of total lysine for pigs from 3-5 kg. The level of total arginine in the experimental diets was 30, 55 and 78% of total lysine, respectively, for the WHEY, HYDROL and ISP diets. Concentration
of plasma urea nitrogen (PUN) was lowest in pigs fed the WHEY diet. This result seems to be contradictory
considering that PUN concentration is positively related to the rate of urea
synthesis and therefore inversely related to the efficiency of N deposition.
Indeed, Coma et al. (1995) have described positive correlations coefficients
between PUN concentrations with lean growth caused by a confounding effect of
ADFI. Quantity of N intake has a
positive relationship with PUN concentrations and because some times ADFI is
also directly related to lean growth (as happened in this experiment) the
expected inverse relationship between PUN and lean growth is not always
observed. Implications Both the hydrolyzed vegetable protein blend and isolated soy protein have been demonstrated to be an excellent alternative to milk proteins used in liquid diet formulations for neonatal pig. Even if the comparison with a milk-protein-based diet was prejudiced by low performance of our positive control, the growth performance data from the alternative protein sources were proven to be very similar to those found in current literature for piglets of same age. Data from this study also underscore that a good amino acid balance may be more important than the source of protein per se. Clearly, much additional work is needed to better define the nutritional (amino acid) requirements of the very young pig. In particular, these data suggest that arginine may be limiting in milk-based proteins. In conclusion, there is a valuable niche for alternative vegetable proteins in liquid diets for very young pigs. Exploitation of this fact will help to make liquid-feeding technology more economically attractive to the swine industry. Acknowledgements
The
authors wish to thank Lori Gatlin, Ryan Odle, Oulayvah Pillips, Simone Pophal
and Lin Xi and for their assistance with experimental design, animal care,
sampling and analytical procedures. ReferencesAOAC. 1997. Official Methods of Analysis. 15th ed. Association of Official Analytical Chemists. Gaithersburg, MD. Azain, M. J., T. Tomkins, J. S. Sowinski, R. A. Arentson, and D. E. Jewell. 1996. Effect of supplemental pig milk replacer on litter performance: Seasonal variation in response. J. Anim. Sci. 74:2195-2202. Chae B. J., In K. Han, J. H. Kim, C. J. Yang, J. D. Hancock, I. H. Kim, and D. A. Anderson. 1999. Effects of dietary protein sources on ileal digestibility and growth performance for early-weaned pigs. Livest. Prod. Sci. 58:45-54. Chaney, A. L. and E. P. Marbach. 1962. Modified reagents for determination of urea and ammonia. Clin. Chem. 8:130. Coma, J., D. R. Zimmerman, and D. Carrion. 1995. Relationship of rate of lean tissue growth and other factors to concentration of urea in plasma of pigs. J. Anim. Sci. 73:3649-3656. Dahlqvist, A. 1964. Method for assay of intestinal dissaccharidases. Anal. Biochem. 7:18-5. Dreau D., J. P. Lalles, V. Philouze-Rome, R. Toullec and H. Salmon. 1994. Local and Systemic Immune responses to soybean protein ingestion in early-weaned pigs. J. Anim. Sci. 72:2090-2098. Fawcett , J. K. and J. E. Scott. 1960. A rapid and precise method for the determination of urea. J. Clin. Pathol. 13:156. Golbarg, J. A., and A. M. Rutemburg. 1958. The colorimetric determination of leucine aminopeptidase in urine and serum of normal subjects and patients with cancer and other diseases. Cancer 11:283-291. Gornall, A. G., Bardawill, C. J. & David, M. M. 1949. Determination of serum protein by means of the biuret reaction. J. Biol. Chem. 177:751-766. Harrell, R. J., M. J. Thomas, and R. D. Boyd. 1993. Limitations on sow milk yield on baby pig growth. Proc. Cornell. Nutr. Conf. Ithaca, NY. Pp. 156-164. Kidder, D. E., and M. J. Manners. 1980. The level of distribution of carbohydrases in the small intestine mucosa of pigs from 3 weeks of age to maturity. Br. J. Nutr. 43:141-153. Jones E. E., J. A. Coalson, and J. G. Lecce. 1997. Soy flour as a source of protein for baby pigs. J. Anim. Sci. 45:1073-1078. Kim J. H., K. N. Heo, J. Odle, I. K. Han and R. J. Harrell. 2001. Liquid diets accelerate the growth of early-weaned pigs and the effects are maintained to market weight. J. Anim. Sci. 79:427-434. Li D.F., J. L. Nelssen, P. G. Reddy, F. Blecha, J. D. Hancock, G. L. Allee, R. D. Goodband and R. D. Klemm. 1990. Transient hypersensitivity to soybean meal in early-weaned pig. J. Anim. Sci. 68:1790-1799. Luna, L. G. 1968. Manual of histologic staining methods of the armed forces institute of pathology. 3rd ed. McGraw-Hill Book Company, New York. Mateo J. P. and T. L. Veum. 1980. Utilization of casein or isolated soybean protein supplemented with amino acids and glucose or lactose by neonatal piglets reared artificially. J. Anim. Sci. 50:870-876. Mavromichalis I., T. M. Parr, V. M. Gabert and D. H. Baker. 2001. True ileal digestibility of amino acids in sow’s milk for 17-day-old pigs. J. Anim. Sci. 79:707-713. McClead Jr. R. E., M. E. Lentz, and R. Vieth. 1990. A simple technique to feed newborns piglets. J. Pediatr. Gastroent. Nutr.10:107-110. McCracken B. A., R. T. Zijlstra, S. M. Donovan, J. Odle, E. L. Lien and H. R. Gaskins. 1998. Neither intact nor hydrolyzed soy proteins elicit intestinal inflammation in neonatal piglets. J. Parent. Enter. Nutr. 22:91-97. Moughan J. P., M. Pedraza, W. C. Smith, M. Williams and M. N. Wilson. 1990. An evaluation with piglets of bovine milk, hydrolyzed bovine milk, and isolated soybean proteins included in infant milk formulas. I. Effect on organ development, digestive enzyme activities, and amino acid digestibility. J. Pediatr. Gastroent. Nutr. 10:385-94. Newport M. J. 1980. Artificial rearing of pigs 11. Effect of replacement of dried skim-milk by an isolated soya-bean protein on the performance of the pigs and digestion protein. Br. J. Nutr. 44:171-178. Newport M. J. and M. J. Henschel. 1985. Growth, digestion, and protein metabolism in neonatal pigs given diets containing whey as the predominant or only source of milk protein. J. Pediatr. Gastroent. Nutr. 4:639-44. NRC, 1988. Nutrient requirement of Swine. 10th ed. National Acadamy Press, Washington, DC. Odle, J. and R. J. Harrell. 1998. Nutritional approaches for improving neonatal piglet performance: Is there a place for liquid diets in commercial production? Asain-Austr. J. Anim. Sci. 11:774-780. Odle, J. and R. J. Harrell. 2001. Liquid diets for early-weaned pigs – A “solution” for post-weaning morbidity. Proc. Cornell Nutr. Conf. pp. 14-24. Oliver, W. T., S. A. Mathews, O. Phillips, E. E. Jones, J. Odle and R. J. Harrell. 2002. Efficacy of partially hydrolyzed corn syrup solids as a replacement for lactose in manufactured liquid diets for neonatal pigs. J. Anim. Sci. 80:143-153. Sohn K. S., C. V. Maxwell, D. S. Buchanan, and L. L. Southern. 1994a. Improved soybean protein sources for early-weaned pigs: I. Effects on performance and total tract amino acid digestibility. J. Anim. Sci. 72:622-630. Sohn K. S., C. V. Maxwell, L. L. Southern and D. S. Buchanan. 1994b. Improved soybean protein sources for early-weaned pigs: II. Effects on ileal amino acid digestibility. J. Anim. Sci. 72:631-637. Uden P., P. E. Colucci and P. J. Van Soest. 1980. Investigation of chromiun, cerium and cobalt as markers in digesta. Rate of passage studies. J. Sci. Food. Agric. 31:625-632. USDA. 2002. Part III: Reference of swine health and environmental management in United States, 2000. USDA:APHIS:VS, CEAH, National Animal Health Monitoring System, Fort Collins, CO. Wolter, B. F, M. Ellis, B. P. Corrigan, and J. M. DeDecker. 2002. The effect of birth weight and feeding of supplemental milk replacer to piglets during lactation on preweaning and postweaning growth performance and carcass characteristics. J. Anim. Sci. 80:301-308. Zijlstra R. T., A. M. Mies, B. A. McCracken, J. Odle, H. R. Gaskins, E. L. Lien and S. M. Donovan. 1996a. Short-term metabolic responses do not differ between neonatal piglets fed formulas containing hydrolyzed or intact soy proteins. J. Nutr. 126:913-23. Zijlstra, R.T., K-Y. Whang, R.A. Easter and J. Odle. 1996b. Effect of feeding a milk replacer to early-weaned pigs on growth, body composition and small intestinal morphology, compared with suckled littermates. J. Anim. Sci. 74:2948-2959. Table 1. Calculated and analyzed composition of experimental dietsa
a Values were calculated for ME, fat, lactose and total tryptophan content of all diets, and all amino acid concentrations were calculated for the Whey/Hydrol diet. Values for crude protein and ash were analyzed for all diets, and amino acid concentrations (except Trp) were analyzed for the Whey, Hydrol, ISP and Casein diets. b The casein diet was fed only in the second replicate of the experiment.
Table 2.
Performance of suckling pigs fed various sources of proteina
a Values are least square means ± SEM; n = 9-12. xyz Within a row, means lacking a common letter are different , P < 0.05. Table 3. Plasma urea nitrogen (PUN) in suckling, 19-d-old pigs fed various proteinsa
a Values are means ± SEM, n = 6 for pH and n = 9-. xyz Within a row, means lacking a common letter are different, P <0.05. Figure 1. Piglet feeding apparatus
Figure 2. Piglet nursing in the piglet feeding apparatus. 
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