Impact of Nano Zinc Supplementation During Transition Period on Reproductive Performance, Serum Biochemical Indices and Metabolic Profile in Purebred Sahiwal Cows

Micronutrients are essential for physiological functions and are especially crucial during the transition period. Zinc is one of such nutrients that plays a vital role in metabolism, immunity, endocrine regulation, reproductive physiology, and uterine health. Nano-zinc, due to its superior bioavailability, offers improved physiological benefits at lower supplementation levels. Twenty-four pregnant purebred Sahiwal cows were randomly assigned to four groups receiving a balanced diet without zinc (T0), zinc oxide at 40 ppm (T1), and nano zinc oxide at 20 ppm (T2) and 40 ppm (T3). Nano-zinc supplementation did not significantly affect reproductive performance but showed a non-significant reduction in the postpartum interval to estrus by 11–20%, and service period by 9.66–16.78%, and an increase in the conception rate compared to other treatments. The concentration of serum zinc varied significantly (P ≤ 0.05) among treatments, with the highest levels observed in the 40 ppm nano-zinc group during both the prepartum and postpartum periods, despite its superior bioavailability. Administration of nano zinc-supplemented groups caused a non-significant increase in cholesterol concentration as compared to other groups and contributed to better reproductive performance. Compared to the different treatments group feeding with nano zinc at 40 ppm showed significantly (P ≤ 0.01) lower concentrations of AST and ALT during prepartum and postpartum periods.