Abstract

ARROYO-LEDEZMA, Jaime; DE LA TORRE-BARRERA, Jannette  and  AVILA-SERRANO, N. Ysac. Reproductive response in hair sheep synchronized with progesterone or prostaglandins. Agrociencia [online]. 2013, vol.47, n.7, pp.661-670. ISSN 2521-9766.

Synchronization adjusts estrus at specific times and allows the use of reproductive technologies. The aim of this study was to evaluate the reproductive response of 30 synchronized hair sheep with progesterone (P4) or prostaglandins. The hair sheep were 5/8 Pelibuey x 2/8 Black Belly x 1/8 Dorper, from 3.5 to 4.0 years of age, with an average weight of 37.8 ±3.0 kg; last parturition occurred 8 months prior to the experiment. The treatments were: 1) application for 11 d of 300 mg of P4 impregnated into a controlled release vaginal device (CIDR) + 400 IU IM of equine chorionic gonadotropin (eCG) after removing CIDR; 2) two doses of 0.075 mg of prostaglandin F_2a (cloprostenol) with an interval of 11 d. The experimental design was completely randomized, with two treatments and 15 replicates; the experimental unit was one sheep. Eight hours after removing CIDR and after applying the second dose of PGF_2a estrus were detected every 2 h for 15 min using males provided with a protection device. Blood samples were collected daily from the jugular vein as from the CIDR placement and the first application of PGF_2a lor 14 d to determine the plasma concentrations of P4. All sheep in the two treatments showed the presence of estrus. The final treatment interval to estrus was shorter (p£0.05) in CIDR + eCG (22.2±2.2 h) than with PGF_2a (33.1 ±2.2 h). The duration of estrus was similar (p>0.05) in both treatments: 54.2±2.6 h for CIDR + eCG and 51.8±2.6 h in PGF_2a. The maximum concentration of progesterone (7.3 ±0.9 ng mL^-1) in CIDR + eCG was observed on days 2 and 5 of the treatments; from day 6 P4 concentration decreased to 2.35±0.2 ng mL^-1 until day 11, and 0.26±0.02 ng mL^-1 24 h after the device removal. In PGF_2a group the concentration of progesterone decreased (p£0.05) from 3.7±0.6 ng mL^-1 on day 0 to 0.87±0.2 ng mL^-1 on day 1, and from 4.37±0.05 ng mL^-1 on day 11 to 0.62±0.06 ng mL^-1 on day 12. Progesterone profiles coincided with the biological action of P4 and CIDR. In hair sheep to synchronize estrus with P4 or PGF_2a leads to similar reproductive responses. In CIDR + eCG treatments, the highest and constant concentration of P4 occurs in the first 5 d; this justifies the implementation of short synchronization protocols.

Keywords : cloprostenol; PGF_2a; CIDR + eCG; hair sheep; estrus synchronization; tropic.

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