Graduate Student Literature Review: The past and future of soy protein in calf nutrition

摘要

Our objective with this review is to encourage moreresearch about the use of soy protein in young calfdiets by learning from the mistakes of the past andacknowledging the promising results found when moderntechniques are applied to treat soybeans. Total orpartial substitution of milk proteins with soy proteinscan represent a substantial increase in the economicefficiency of calf diets as long as it does not affect calfperformance. Unfortunately, the results found in theliterature indicate that the inclusion of soy protein indiets of young calves usually diminishes growth andhealth outcomes. The interaction of the antinutritionalfactors and antigenic proteins in soybeans with thegastrointestinal tract triggers a physiological responsewith negative consequences for the digestive tract andimmune system of the calf. In this article, we highlightthe importance of a correct processing method ofsoybeans by reviewing some of the published researchthat has evaluated different soy-based ingredients indiets for young calves. Conventional methods such asheating, ethanol extraction, and protein isolation canproduce favorable results provided that the final productcontains minimum or null amounts of antigenic andantinutritional factors. More recently, further processingmethods such as microbial treatment of soybeanmeal reduces those antinutritional and antigenic factors,and can also increase the quality of soy protein byreducing the peptide size and by triggering the releaseof bioactive compounds. Experiments in which soy proteinmodified by this method was fed have increasedin the scientific literature during the last decade dueto the favorable results obtained in calves as well as inmonogastric animals.