Effects of colostrum processing on metabolic and endocrine parameters during early postnatal life in calves.

Colostrum feeding is essential for calf immunity, nutrition, and neonatal survival. To ensure availability when maternal supply is insufficient, various storage and preservation methods have been adopted in dairy management. The objective of this study was to investigate the effects of different colostrum processing methods on metabolic and endocrine parameters in newborn calves. Eighteen calves (15 Holstein Frisian, 3 Holstein × Limousin crossbreds) were separated from their dams immediately after birth and assigned to 1 of 3 groups. Calves were fed 2.5 L of either pooled unprocessed colostrum (UPC), pooled heat-treated colostrum (HTC), or vacuum-dried colostrum (VDC) produced from the same unprocessed colostrum batch at 4 h and 12 h postpartum (p.p.). On d 2 and 3 p.p., animals received transition milk (bulk tank milk mixed with 10% of the respective colostrum source), and from d 4 onward bulk tank milk twice daily. Blood samples were collected at 4, 12, and 24 h p.p., and thereafter once daily until d 7 p.p. before morning feeding. Metabolic and endocrine parameters including total protein, IgG, aspartate aminotransferase, gamma-glutamyl transferase (GGT), glucose, insulin, cortisol, glucagon, nonesterified fatty acids (NEFA), triglycerides (TG), and total cholesterol (TC) were analyzed. Total protein and IgG concentrations were greater in HTC and VDC until d 2 compared with UPC. Activity of GGT at 12 h p.p. was greater in HTC and VDC compared with UPC. Insulin concentrations did not change in HTC or VDC until d 2, whereas a decline was observed in UPC after 12 h p.p. Glucagon concentrations were greater in HTC and VDC up to d 2 compared with UPC. Cortisol concentrations decreased in all groups until 24 h p.p. Colostrum processing did not affect lipid metabolism-related parameters, including NEFA, TG, and TC. Our results demonstrate that heat treatment and vacuum-drying of colostrum were associated with differences in circulating IgG, metabolic, and endocrine parameters in neonatal calves, suggesting potential effects on postnatal metabolic adaptation.