Resumen

MARTINEZ-BARBITTA, M; GONZALEZ-GUASQUE, W; MARTINEZ-PINA, M  y  CAVESTANY, D. 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. Veterinaria (Montev.) [online]. 2015, vol.51, n.197, pp.3-3. ISSN 0376-4362.

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). E₂ concentrations reached a maximum 4 hours after treatment for E17 and EB groups and 28 h after treatment for ECP groups. Maximum average concentrations were E17: 641.5±11.5 pg/mL, EB: 166.5±11.5 pg/mL and ECP: 45.6±10.9 pg/mL (P<0.0001). E₂ returned to baseline levels 40 hours later in E17 and EB groups and 80 hours in ECP groups. The average follicular diameters at the Day 8 were 14.9±1.4 and 14.4±1.3 mm for the EB and E17 cows and 10.9±1.4 for the ECP animals (P<0.05). Ovulation occurred earlier in E17 and was 88.9% in EB, 66.7% in E17 and 30.0% to ECP (P<0.05).

Palabras clave : dairy cows; estrus synchronization; ovulation; estradiol; progesterone.

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