247 Interaction between colostrum and milk replacer supply on growth, development and fecal consistency of dairy surplus calves

Abstract This study examined the interactions between early life nutrition strategies and their impact on growth, development, and fecal consistency in surplus bull calves. Holstein-Friesian bull calves n = 120; body weight (BW) = 43.1±3.56 kg were enrolled. In the first 12 h after birth, calves were fed either 2 L (100 g of IgG) or 6L (300 g of IgG) of colostrum replacer (CR) to obtain either failure (F) or successful (S) transfer of passive immunity, respectively. Upon arrival at the facility, serum IgG concentrations were measured; therefore, F and S calves were identified accordingly and randomly assigned to one of two milk replacer (MR) feeding schemes: Moderate (Mod; ~8 L) or Low (Low; ~4 L). In total, there were 4 treatments resulting from the 2 × 2 factorial design: F-Mod, F-Low, S-Mod, S-Low (n = 30/treatment). Calves were individually housed and fed twice daily until d 42, gradually weaned until d 56, and had free access to straw and water during the study. On d 22, a calf pelleted starter was offered. To evaluate organ and gastroinstetinal tract development, 10 calves/treatment were euthanized at 84 d of age. Other measurements include weekly BW, daily intakes, and daily fecal score until d 21. Data were analyzed by PROC MIXED in SAS accounting for the fixed effects of block, CR, MR, and time, and their interaction. Time entered the model as a repeated statement, and initial BW was used as a covariable when appropriate. Initial BW was not different across treatments, whereas serum IgG was greater in S calves (S = 1,962.9 vs. F = 941.0 mg IgG/dL). During the study, BW was influenced by both CR (P = 0.001) and MR (P 0.001), where S and Mod calves consistently exhibited greater BW when compared with F and Low calves, respectively. At d 84, Mod calves (F-Mod and S-Mod) were on average 18 kg heavier than Low calves. Similarly, Mod calves exhibited greater fresh tissue weights in the liver, pancreas, spleen, and both the small and large intestines (P 0.05). Starter intake was influenced by MR (P 0.001), with Low calves having the greatest intake before and during weaning. However, post-weaning starter intake was greater (P = 0.010) in Mod calves. Fecal consistency was influenced by CR (P = 0.001) and MR (P 0.001), with S and Low calves having improved fecal consistency. Although no interactions were observed between CR and MR, these findings underscore the importance of considering both colostrum and MR levels in calf nutrition management to optimize growth and improve animal welfare during the early stages of life.