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Interpretive Summary: Impacts of polyclonal antibody preparations from avian origin as a feed additive to beef cattle: immune responses during the step-up transition diets       

By: Dr. Emily Taylor

Acidosis in feedlot cattle is common, especially during the transition period from high forage to a grain-heavy diet. Nutritionists are consistently looking for alternatives to mitigate the adverse effects associated with this transition. Polyclonal antibody preparations (PAP) have been previously investigated; however, this is the first study evaluating the effects of PAP on the immune response of beef steers during the transition from high forage to a grain-heavy diet. The objective of the current study was to evaluate the effects of feeding PAP against Streptococcus bovis, Fusobacterium necrophorum, and lipopolysaccharides (LPS) as a strategy to minimize systemic inflammation in beef cattle. 

Eight ruminally cannulated beef steers were transitioned to a high-grain diet over a 21-d period. The transition consisted of three 7-d steps of increased inclusion of cracked corn (35%, 60%, and 82% of the diet dry matter for STEP1, STEP2, and STEP3, respectively). Evaluation of immune responses included haptoglobin, serum amyloid A, rectal temperature, leukocyte counts, and expression of cell adhesion molecules cluster of differentiation CD11b, CD14, and CD62L. 

As expected, the step-up transition from forage to high-grain diets triggered systemic inflammation in beef steers, observed by an increase in plasma concentrations of haptoglobin, serum amyloid A, and the expression of adhesion molecules in leukocytes. Authors suggest that hindgut acidosis may have been present, which could add to systemic inflammation. However, little in the literature is dedicated to isolating the different effects of acidosis in the rumen and hindgut. Therefore, it is difficult to determine the exact contribution of each gastrointestinal section while cattle are inflicted. In conclusion, feeding PAP against S. bovis, F. necrophorum, and LPS did not provide benefit to mitigate inflammation in this study. 

This article is available in the Journal of Animal Science.