How the FSH/LH ratio and dose numbers in the p-FSH administration treatment regimen, and insemination schedule affect superovulatory response in ewes.
We wished to evaluate the effects of FSH/LH ratio and number of doses of p-FSH during a superovulatory treatment on ovulation rate and embryo production (Experiment I). In Experiment II, we studied the efficacy of fertilization after various insemination schedules in superovulated donors. In Experiment I estrus was synchronized in 40 ewes (FGA, for 9 days plus PGF2alpha on Day 7) and the ewes were randomly assigned to four treatment groups as follows (n = 10 ewes each): Group A: four p-FSH doses with the FSH/LH ratio held constant (1.6); Group B: four p-FSH doses with the FSH/LH ratio decreasing (FSH/LH 1.6-1.0-0.6-0.3); Group C: eight p-FSH doses with the FSH/LH ratio held constant (1.6); Group D: eight p-FSH doses and FSH/LH ratio decreasing (1.6-1.6, 1.0-1.0, 0.6-0.6, 0.3-0.3). p-FSH administrations were performed twice daily 12 h apart. The ewes were mated at the onset of estrus and again after 12 and 24 h; then, one ram per four ewes was maintained with the ewes for two additional days. Ovarian response and embryo production were assessed on Day 7 after estrus. Experiment II. Three groups (n = 10 each) of superovulated ewes were inseminated as follows: Group M: mated at onset of estrus; Group AI: artificial insemination 30 h after onset of estrus; M + AI) mating at onset of estrus and intrauterine AI performed 30 h from estrus with fresh semen. Results of Experiment I showed that treatment (D) improved (P < 0.05) ovulatory response in comparison to Groups (C) and (A). The fertilization rate was lower (P < 0.01) in Group D) than Group (A). Also the proportion of transferable embryos was lower in Group (D) in comparison to all the other treatments (P < 0.01). Group A gave the best production of embryos (7.3/ewe; 89.0% transferable). In Experiment II, combined mating plus AI improved fertilization rate (80.3%) compared to both mating (P < 0.01) and AI (P < 0.02) alone.
D'Alessandro
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AG
Department of Progettazione e Gestione delle Risorse Agro-Zootecniche e Forestali-PRO.GE.SA., University of Bari, Via G. Amendola, 165/A, 70126 Bari, Italy. dalex@agr.uniba.it
Martemucci
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G
Taibi
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L
D000818:Animals; D005260:Female; D005306:Fertilization; D005640:Follicle Stimulating Hormone / Q000008:administration & dosage* / Q000097:blood*; D007315:Insemination, Artificial / Q000379:methods / Q000662:veterinary*; D007986:Luteinizing Hormone / Q000097:blood*; D011247:Pregnancy; D012621:Seasons; D012756:Sheep; D013480:Superovulation
D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone