Comparison of different estradiol and progesterone formulations in an estrus synchronization protocol in lactating Holstein cows in a pasture-based system: hormonal profiles and ovarian response

Abstract

The objective was to evaluate three estradiol (E2) formula­tions [5 mg of 17β (E17), 1 mg of benzoate (EB) and 1 mg of cypionate (ECP)] and two presentations of progesterone (P4) - intravaginal device (DIV) with 558 mg of P4 200 mg of P4 parenteral (MAD-4) - in an ovulation synchroniza­tion protocol. Thirty lactating Holstein cows were presyn­chronized with a combination of GnRH and Prostaglandin (PG) given seven days apart and responding with a stand­ing heat on the same day were selected; 10 days 6 groups were formed (n=5 each): 1) DIV+EB: Day 0: DIV + EB; Day 8: PG and DIV withdraw; Day 9: EB. 2) DIV+E17: Day 0: DIV + E17; Day 8: PG and DIV withdraw; Day 9: E17. 3) DIV+ECP: Day 0: DIV + ECP; Day 8: PG, DIV withdraw + ECP. 4) MAD-4+EB: Day 0: MAD-4 + EB; Day 8: PG; Day 9: EB. 5) MAD-4 + E17: Day 0: MAD-4 + E17; Day 8: PG; Day 9: E17. 6) MAD-4 + ECP: Day 0: MAD-4 + ECP; Day 8: PG + ECP. The response was eval­uated by plasma levels of E2 and P4 and ovarian ultraso­nography. The maximum average P4 concentrations were reached one hour after the treatment (7.3±0.7 ng/mL DIV and 16.1±0.7 ng/mL MAD-4; P<0.0001); six hours lat­er were reduced to 11.2±0.7 ng/mL DIV and 5.7±0.7 ng/ mL MAD-4 respectively (P<0.0001).