Dietary organic trace mineral supplement affects steroid hormone, antioxidant enzyme concentrations, and reproductive performances in dairy cows

Abstract

Supplementation of organic trace mineral (OTM) may affect reproductive functions in several aspects and has been studied, but very rare is reported in dairy cows. To determine the effects of dietary OTM supplement during pre- and postpartum with timed artificial insemination (TAI) protocol on steroid hormones, antioxidant enzymes, and reproductive performances in dairy cows. Prepartum Holstein cows (n = 60) were randomly assigned to received either a control diet or OTM supplemented for 42 days. Both groups were fed the same total mixed ration, but were supplemented with 5 g/head/d OTM (Bioplex®) in the treatment group. Blood and follicular fluid samples were collected to determine progesterone (P4), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and estradiol (E2) concentrations. Cows fed OTM had better placental expulsion period, milk yield, and reproductive performance parameters (day to first ovulation and estrus, percentage of first estrus and size of preovulatory follicle) than control cows (P < 0.05). Cows fed OTM affected (P < 0.05) the serum concentration of P4 on days 12, 15, 18, 21, and 42 after TAI. Follicular fluid concentrations of E2 in large follicle in OTM cows were greater than control cows (336.3 and 376.9 ng/mL; P < 0.05). Cows supplemented with OTM had greater serum SOD and GSH-Px activities than control cows (15.5 vs. 10.6 U/mL and 12.1 vs. 9.9 U/mL; P < 0.05). In conclusion, supplements with OTM improved uterine and placental health, steroid hormones concentrations, and antioxidant enzyme activities but did not improve conception rate in dairy cows.