The Effects Of Colostrum Composition And Source Of Trace Minerals In Milk Replacer On Early-Life Calf Metabolism, Performance, And Health

Dairy calf nutrition aims to improve the nutritional components offered to calves and to improve delivery methods to support their performance and health. Morbidity and mortality remain major challenges, and early-life nutrition may help address them. Calves rely on nutrients from bovine colostrum and later on a liquid and solid diet to transition from a neonate to the pre-weaning phase and finally to a post-weaning animal. Bovine colostrum, produced in the weeks before and excreted shortly after birth, delivers essential immune and growth-supporting factors. The first part of this research is a scoping review of bovine colostrum composition, focusing on secondary components and their effects on neonatal calf physiology and metabolism. While immunoglobulin G (IgG) is the primary indicator of passive immunity, colostrum also contains growth factors, hormones, amino acids, proteins, cytokines, oligosaccharides, fatty acids, vitamins, and minerals. We examined how nutritional, genetic, and management factors influence their presence, how concentrations change from colostrum to transition and mature milk, and their specific effects on calf development. These components play diverse roles in early life, but more research is needed to understand individual variation and interactions among them. The second part is an experiment evaluating how casein presence in colostrum fed to dairy calves affects IgG absorption rate and passive immune transfer. Seventy-one Holstein × Angus calves were randomly assigned to receive maternal colostrum (MC), a whey-based colostrum replacer without casein (CR–C), or one with added casein (CR+C). Casein presence reduced the apparent efficiency of IgG absorption (AEA) compared to CR–C but not MC. Vigor scores were unaffected. These results suggest casein presence in colostrum influences IgG absorption and its dynamics. Finally, milk replacers are commonly used in commercial systems to meet nutritional needs and may be formulated with different sources of trace minerals (TM) to enhance bioavailability, support immune development, and improve growth performance during the pre-weaning period. The third part involved two experiments assessing how trace mineral source in milk replacer (organic vs. sulfate) affects calf health and performance during the preweaning period. Both MR types met NASEM requirements for Zn, Cu, Fe, and Mn. Experiment 1 included 43 Holstein male and female calves; Experiment 2 involved two blocks of Holstein male calves (63 and 64 calves). No differences were observed in performance or health outcomes. Serum potassium and cobalt concentration differed in Experiment 1 but not Experiment 2. Liver TM concentration were unaffected, and only urea concentration differed in Experiment 2. Overall, TM source had minimal effects on calf performance, health, and mineral status. These studies advance our understanding of dairy calf nutrition and help inform strategies to reduce morbidity and mortality during early life.