Effects of supplementing Holstein heifers with dietary melatonin during late gestation on serum antioxidant capacity and anti-Müllerian hormone of offspring
Previously, our laboratory observed an increase in maternal serum antioxidant capacity during late gestation dietary melatonin supplementation. Therefore, the objective was to examine the effects of supplementing melatonin to dams during late gestation on offspring serum antioxidant capacity and anti-Müllerian hormone concentrations. On d 190 of gestation, heifers (n = 20) were blocked by BW and then randomly assigned to one of two dietary treatments: 1). 20 mg of dietary melatonin per day (MEL) or 2). no melatonin supplementation (CON). Dietary treatments were terminated on day 262 of gestation. MEL heifers received 2 mL of 10 mg/mL melatonin in ethanol while CON heifers received 2 mL of ethanol alone. At birth, calves were separated from their dams and given 3.8L of colostrum. Calves were fed 5.7L of whole milk daily and offered 0.9 kg/d of starter grain. Starter was increased by 0.9 kg/d when orts were 0 kg. Calf (n = 18) total antioxidant capacity was determined in serum on wk 0, 1, 2, 3, and 4 of age. Concentrations of anti-Müllerian hormone were determined in female offspring (n = 15) on wk 4 of age. Data were analyzed using the mixed procedure of SAS. For repeated measures the model statement contained treatment, age, and their respective interaction. Total antioxidant capacity was not different (P = 0.14) between calves from MEL treated dams vs. calves from CON treated. A main effect of age (P < 0.001) was observed for total antioxidant capacity, which was increased at wk 1 of age vs. 0, 2, 3, and 4. Concentrations of anti-Müllerian hormone tended to be increased (P< 0.10) in heifer calves from MEL treated dams (0.82 ± 0.19 ng/mL) vs. calves from CON treated dams (0.35 ± 0.19 ng/mL). In conclusion, the increase in maternal antioxidant capacity following dietary melatonin supplementation did not affect calf antioxidant capacity of serum during early postnatal development. Interestingly, the tendency for increased heifer calf anti-Müllerian hormone concentrations deserves further investigation into offspring ovarian reserves.
Keywords: anti-Müllerian hormone, antioxidant, melatonin