101 Effects of vitamin B complex supplementation on blood metabolites and performance of weaned beef calves during a 42-day preconditioning program.

Preconditioning programs aim to improve calf health and performance by reducing stress and enhancing adaptability post-weaning and transportation. Stress during this period may negatively impact immune function, increase cortisol concentration, reduce feed intake and growth efficiency. It may also affect vitamin B synthesis by ruminal microbes. This study evaluates the effects of vitamin B complex supplementation on blood metabolites and feed intake in calves during a 42-day preconditioning program at the Eastern Oregon Agricultural Research Center (EOARC; Burns, Oregon). A total of sixty-three Angus × Hereford calves were stratified by body weight (BW) after weaning (d0) and allocated into 21 pens, with 3 calves per pen. Pens were randomly assigned to one of three treatments: (1) Control, (2) VitB1, or (3) VitB2. Calves assigned to vitamin B supplementation received vitamin B complex (1 vs. 2g/calf daily; Vivalto®, Selko® USA) mixed with 1.3 kg of dried distillers’ grains (DDG), while calves in the Control group received only DDG, serving as a negative control. Blood samples were collected on days 0, 1, 3, 7, 14, 21, and 42 to measure blood metabolites, and feed intake was recorded daily. All calves had free access to chopped alfalfa-grass hay and whole corn. Body weight was measured at weaning (d0) and d1, with the average used as the weaning weight. Blood samples were analyzed for cortisol, haptoglobin, and ceruloplasmin. Variables were analyzed as repeated measures using the MIXED procedure in SAS (SAS Inst. Inc., Cary, NC, USA). Statistical significance was set at P ≤ 0.05. Weaning weights were similar at the start of the study (252 ± 3.6 kg; P = 0.82). No treatment effects were found on final BW (283, 283, and 284 kg for Control, VitB1, and VitB2, respectively; P = 0.98) or average daily gain (0.735, 0.795, and 0.747 kg/d for Control, VitB1, and VitB2, respectively; P = 0.53). No treatment (P = 0.34) or treatment × day (P = 0.59) effects were observed for total feed intake. Similarly, no treatment effects (P = 0.71) were observed for blood cortisol concentrations. However, a day effect was found (P < 0.001), with a tendency for a treatment × day interaction (P = 0.08). On d3, cortisol concentrations were greater for VitB1 calves (2.18 µg/dL; P = 0.04) compared to Control (1.69 µg/dL), with VitB2 intermediate (1.77 µg/dL; P = 0.11). At the end of preconditioning, on the d42, cortisol concentrations were greater for calves assigned to Control treatment compared to calves assigned to vitamin supplementation regardless of level (2.46, 1.99, and 1.90 µg/dL, respectively for Control, VitB1, and VitB2). Vitamin B complex supplementation during preconditioning did not affect feed intake or calf performance but ameliorated cortisol concentrations by the end of the preconditioning.