PSXIV-24 Immune function and growth performance in beef calves supplemented during backgrounding with live yeast and yeast cell wall in combination with supplemented dams

Live yeast and yeast cell wall products potentially improve health and performance in cattle during the stocker and feedlot phases. Therefore, the objective of this study was to investigate yeast-product supplementation during late gestation through 88 d of age, and(or) a 42-d backgrounding period on immune function and growth performance. Late gestation cows (n = 97) were assigned randomly to treatment: 1) supplement without yeast (CON) or 2) supplement with yeast products (YP). At weaning, calves from each dam treatment (CON or YP) were pooled by dam treatment and stratified based on BW, sex, dam parity, and sire and split into 8 pens within dam treatment. Pens were assigned randomly to 1 of 2 backgrounding treatments (CON or YP) such that a total of 4 pens/treatment existed. Treatments included: 1) dam YP, calf YP, 2) dam YP, calf CON, 3) dam CON, calf YP, and 4) dam CON, calf CON. Calves were fed 2 kg/d of grain and yeast (5 g/d) was provided in a top-dress (ground corn plus YP). Weaning weights (P = 0.99) and backgrounding ADG (P = 0.29) did not differ. Total ruminal VFA concentrations, sampled on d 0 and 42 post-weaning, were increased in calves from dams supplemented with YP (P = 0.04). There were no effects of treatment (P ≥ 0.32) on molar proportions of acetate and propionate. Haptoglobin (P ≥ 0.49) and neutrophil:lymphocyte ratio (P ≥ 0.46) were not influenced by treatment but were affected by day (P < 0.01). While there was no effect of YP (P = 0.73) on BVD titers, there was a day effect (P < 0.01) where titers were greatest on d 28 and least on d 0. Post-weaning yeast supplementation in combination with dam supplementation did not improve calf immune function or performance during a 42-d backgrounding period.