Postnatal phenotypic stability and endocrine homeostasis in Holstein-Friesian heifers conceived via multiple ovulation and embryo transfer vs. artificial insemination.

While Multiple Ovulation and Embryo Transfer (MOET) is a cornerstone for accelerating genetic progress in dairy cattle, empirical data directly comparing the postnatal physiological trajectories of MOET-derived calves against conventional Artificial Insemination (AI) remain limited. This study investigated the growth dynamics, somatotropic axis (GH, IGF-1), metabolic signalling (leptin), and immunological maturation (IgG) of Holstein-Friesian heifers (n = 20) from birth through seven months of age. Calves (MOET n = 10; AI n = 10) born to heifer dams, were reared under standardized environmental, nutritional and colostrum management protocols to isolate the effects of reproductive technology. Beyond birth, no statistically significant differences in body weight were detected and body height did not differ significantly between groups across the monitoring period (P > 0.05). Similarly, serum concentrations of leptin, growth hormone, and insulin-like growth factor-1 exhibited no significant divergence between groups. Serum immunoglobulin G levels showed a transient significant difference in one month old calves (P < 0.05) before leveling off by month 3. Strong positive correlations were observed between height and weight across all developmental stages (P < 0.01). These findings suggest that under controlled management conditions, MOET-derived heifers exhibit postnatal growth, endocrine profiles, and immune maturation comparable to AI-conceived counterparts, supporting the functional reliability of MOET protocols in high-performance dairy breeding.