Ovulatory response and embryo yield in superovulated holstein heifers given a priming dose of FSH-P at day 2 of the estrous cycle.
Mature Holstein heifers were given either a priming dose of follicle-stimulating hormone-pituitary (FSH-P, 10 mg) or saline on Day 2 of the estrous cycle, or no pretreatment. All animals were subsequently given a decreasing dose superovulatory treatment of FSH-P beginning between Days 8 and 14, coupled with an injection of prostaglandin F2a to induce luteolysis. Pretreatment with FSH-P had no effect on the total superovulatory response or on the number of transferable embryos collected at Day 7 of gestation. Comparison of the results of our study with previous reports in the literature may suggest that FSH-priming early in the cycle may be advantageous in promoting superovulation only when the superovulatory response of the population of animals is otherwise weak.
Rieger
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Centre de recherche en reproduction animale Faculté de médecine vétérinaire Université de Montréal C.P.5000, St-Hyacinthe, Québec, Canada, J2S7C6.
Desaulnier
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Goff
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