Associations of individual nutrient and non-nutrient factors on endocrine and metabolic parameters in neonatal calves fed colostrum from their own dams

Limited knowledge exists on the role of variation in individual colostrum components on metabolic and endocrine adaptation in calves. The objective of this study was to investigate the effects of individual colostral macronutrients and non-nutrient factors on metabolic and endocrine blood parameters of neonatal calves. Forty-six Holstein calves were fed with colostrum from their own dams at 4 and 12 h postpartum (p.p.). Blood samples were taken before feeding at 4, 12, and 24 h of age. Individual colostrum samples were analyzed for fat, protein, and lactose. Furthermore, concentrations of IgG, insulin, insulin-like growth factor (IGF)-1, and adiponectin were analyzed in colostrum. In blood samples, concentrations of IgG, total protein (TP), glucose, nonesterified fatty acids (NEFA), phospholipids (PL), triglycerides (TG), total cholesterol (TC), insulin, glucagon, IGF-1, and cortisol, as well as the activities of aspartate aminotransferase, and gamma-glutamyl transferase were measured. A mixed-effects model with time as fixed effect was used to evaluate temporal changes in blood parameters and to verify associations between colostral and plasma variables. In addition, Pearson correlation coefficients between colostrum and blood variables were calculated. We observed notable increases in plasma glucose, TP, and IgG concentrations. Plasma PL, TG, and TC concentrations were elevated only after 24 h p.p. Conversely, plasma NEFA concentration declined following initial colostrum intake. Significant correlations were observed between colostral fat content and plasma PL (r = 0.65 at 12 h p.p., r = 0.76 at 24 h p.p.), TG (r = 0.51 at 12 h p.p., r = 0.54 at 24 h p.p.), and TC (r = 0.42 at 12 h p.p., r = 0.67 at 24 h p.p.), which emphasizes the importance of colostral fat as an energy source. With regard to the immunization process, we identified associations between colostral protein with plasma TP (r = 0.45 at 12 h p.p., r = 0.49 at 24 h p.p.) and IgG (r = 0.56 at 24 h p.p.); between colostral lactose content and plasma IgG (r = -0.26 at 12 h p.p.), TP (r = -0.45 at 12 h p.p., r = -0.50 at 24 h p.p.), and IgG (r = -0.42 at 24 h p.p.); between colostral IgG and serum IgG (r = 0.28 at 12 h p.p., r = 0.62 at 24 h p.p.) and TP (r = 0.54 at 24 h p.p.); between colostral insulin and serum IgG (r = 0.52 at 12 h p.p., r = 0.40 at 24 h p.p.) and TP (r = 0.40 at 12 h p.p., r = 0.44 at 24 h p.p.); and between colostral adiponectin and serum IgG (r = 0.37 at 12 h p.p.) and plasma TP (r = 0.51 at 12 h p.p.). In conclusion, distinct associations between colostrum components and the metabolic and immunological status of neonatal calves were observed when own-dam colostrum was fed. The correlations suggest that lactose, insulin, and adiponectin may influence IgG uptake, potentially through effects on intestinal development and closure, although these interpretations should be viewed as preliminary and require further confirmation.