Colostrum management has traditionally focused on the first 24 hours of life, but research from McCarthy et al. (2024, Journal of Dairy Science) suggests the window of benefit extends further. In a trial of 200 Holstein heifers, every calf received the same strong start — two colostrum replacer feedings at 0 and 12 hours, delivering 205 g IgG each — and all achieved successful passive transfer, with no difference in serum IgG between groups. What varied was what followed: small amounts of colostrum replacer blended into milk replacer, either as a short, high-dose protocol on days 2 and 3 or as a longer, low-dose protocol through day 14. Both short-term and long-term approaches reduced the risk of diarrhea in the first 21 days of life, with control calves facing 1.8x and 1.6x greater risk, respectively. Calves on the extended protocol also showed a 3.8x lower hazard of mortality than controls. Notably, total diarrhea days and number of bouts did not differ between groups, indicating reduced risk over time rather than the elimination of disease. Due to serum IgG being identical across all groups, the protective effect cannot be attributed to greater antibody absorption, pointing instead to the local benefits colostrum continues to provide in the gut beyond day one, and reframing colostrum as a nutritional strategy with a longer window than previously assumed.
SCCL supported this research through product, funding and co-authorship