Evaluation of bovine colostrum replacer supplementation to improve weaning transition in Holstein dairy calves.

The objective of this randomized controlled trial was to evaluate the efficacy of supplementing bovine colostrum replacer during weaning to reduce intestinal permeability and improve gain. For this experiment, 65 calves were enrolled and housed individually until 70 d of age. Calves were fed milk replacer (150 g/L) 3 times daily with 9, 10.5, 11.25, and 12 L/d offered from d 1 to 7, 8 to 14, 15 to 21, 22 to 56, respectively. Calves were weaned over 8 d from d 57 to 64, receiving a total of 7.8 L in 2 meals per day from d 57 to 60 and 3.8 L/d in 1 feeding from d 61 to 64. At d 57, calves were blocked by birth weight and randomly assigned to 1 of 2 treatments, equal in ME, which were fed once daily during weaning from d 57 to 64: control (CON; n = 31 calves): 3.8 L of milk replacer (150 g/L) fed by nipple bottle, or colostrum supplementation (COL; n = 34): a mixture of 1 L of bovine colostrum replacer (125 g/L) and 3 L of milk replacer (150 g/L) with 3.8 L of of the mixture fed by nipple bottle. Serum IgG was measured within 48 h of birth and BW was taken at d 0, 57, 60, 64, 70, 77, and 84. Starter intake and bovine respiratory disease (BRD) score were measured daily from d 50 to 70, and fecal consistency was examined daily from d 56 to 70. Serum BHB and lung consolidation were evaluated at d 57, 64, and 70, and intestinal permeability was assessed by recovery of chromium-EDTA, lactulose, and d-mannitol from plasma after oral administration at d 56 and 65. Body weight had no difference between treatment groups at the start of weaning, but COL were 2.79 kg (95% CI: 0.90-4.68) and 2.76 kg (95% CI: 0.86-4.65) heavier than CON at d 77 and 84, respectively. Additionally, COL tended to gain 100.00 g/d more than CON calves (95% CI: -10.41-207.13) from d 57 to 84. No differences were observed in any of the other variables measured. Supplementation of bovine colostrum replacer during weaning may improve weight gain, but the mechanism of action is not clear.