title: Alternatives to improve a prostaglandin-based protocol for timed artificial insemination in sheep.
abstract: The objective was to improve the reproductive performance of a prostaglandin (PG) F(2α)-based protocol for timed artificial insemination (TAI) in sheep (Synchrovine®: two doses of 160 μg of delprostenate 7 d apart, with TAI 42 h after second dose). Three experiments were performed: Experiment 1) two doses of a PGF(2α) analogue (delprostenate 80 or 160 μg) given 7 d apart; Experiment 2) two PGF(2α) treatment intervals (7 or 8 d apart) and two times of TAI (42 or 48 h); and Experiment 3) insemination 12 h after estrus detection or TAI with concurrent GnRH. Experiments involved 1131 ewes that received cervical insemination with fresh semen during the breeding season (32/34 °S-58 °W). Estrous behaviour, conception rate, prolificacy, and fecundity (ultrasonography 30-40 d), were assessed. In Experiment 1, ewes showing estrus between 25 and 48 h or at 72 h after the second PGF(2α) did not differ between 80 and 160 μg of delprostenate (73 vs 86%, P = 0.07; and 92 vs 95%, P = NS, respectively). Conception rate and fecundity were lower (P < 0.05) using 80 vs 160 μg (0.24 vs 0.42, and 0.27 vs 0.47, respectively). In Experiment 2, giving PGF(2α) 7 d apart resulted in higher (P < 0.05) rates of conception (0.45 and 0.51) and fecundity (0.49 and 0.53) than treatments 8 d apart (conception: 0.33 and 0.29; fecundity: 0.33 and 0.34) for TAI at 42 and 48 h, respectively. In Experiment 3, rates of conception, prolificacy and fecundity were similar (NS) between Synchrovine® with TAI at 42 h (0.50, 1.13, and 0.56) and AI 12 h after estrus detection (0.47, 1.18, and 0.55), and Synchrovine® plus GnRH at TAI (0.38, 1.28, and 0.49). However, all TAI treatments had lower (P < 0.05) prolificacy and fecundity compared to AI following detection of spontaneous estrus (1.39 and 0.83, respectively). In conclusion, the Synchrovine® protocol was: a) more successful using 160 vs 80 μg delprostenate; b) more successful with a 7 d than 8 d PGF(2α) interval; c) similarly effective for TAI versus AI 12 h after estrus detection; and d) not improved by giving GnRH at TAI.
authors.affiliation: Departamento de Salud en los Sistemas Pecuarios, Área de Producción y Sanidad Ovina, Facultad de Veterinaria, EEMAC. Ruta 3 Km 363. 60000 PO Box 57072 Paysandú, Uruguay. joliveramuz@gmail.com
authors.forename: J
authors.initials: J
authors.lastname: Olivera-Muzante
authors.forename: J
authors.initials: J
authors.lastname: Gil
authors.forename: S
authors.initials: S
authors.lastname: Fierro
authors.forename: A
authors.initials: A
authors.lastname: Menchaca
authors.forename: E
authors.initials: E
authors.lastname: Rubianes
mesh_terms: D000818:Animals; D015237:Dinoprost / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology*; D004973:Estrus Synchronization / Q000379:methods*; D005260:Female; D005300:Fertility Agents, Female / Q000008:administration & dosage / Q000494:pharmacology*; D007315:Insemination, Artificial / Q000379:methods / Q000662:veterinary*; D011247:Pregnancy; D018873:Pregnancy Rate; D011461:Prostaglandins F, Synthetic / Q000008:administration & dosage / Q000494:pharmacology*; D012756:Sheep / Q000502:physiology*; D013997:Time Factors
chemical_list: D005300:Fertility Agents, Female; D011461:Prostaglandins F, Synthetic; D015237:Dinoprost; C050851:delprostenate