Effects of short-term intravaginal progestagens on the onset and features of estrus, preovulatory LH surge and ovulation in sheep

• Published in: Animal reproduction science Vol. 197; pp. 317 - 323
• Main Authors: Martinez-Ros, Paula, Astiz, Susana, Garcia-Rosello, Empar, Rios-Abellan, Alejandro, Gonzalez-Bulnes, Antonio
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.10.2018
• Subjects: Animals; Dinoprost; Estradiol - blood; Estrous synchronization; Estrus - drug effects; Estrus - physiology; Estrus Synchronization; Female; Luteinizing Hormone - blood; Ovine; Ovulation - drug effects; Ovulation - physiology; Progesterone; Progestins - pharmacology; Sheep; Ovine; Estrous synchronization
• ISSN: 0378-4320; 1873-2232
• DOI: 10.1016/j.anireprosci.2018.08.046

In the present study, there was a comparison among classical long-term progestagen (fluorogestone acetate) protocols for synchronization of estrus and ovulation (14 days; group FGA14, n = 9 ewes) and short-term protocols based on 7 days of progestagen treatment plus a dose of prostaglandin F2α at either insertion (PG-FGA7, n = 11) or removal (FGA7-PG, n = 12). There were no significant differences in the ovulation rate and progesterone secretion among treatments. The FGA7-PG group, however, had a similar percentage of ewes expressing estrous behavior than the group FGA14 (90.9 and 100%, respectively, with a trend for a lesser percentage in the PG-FGA7 group, 63.6%) and about 90% of the ewes in the FGA7-PG group had the preovulatory surge release of LH 8 h after the onset of estrous behavior. These features may be related to a greater number of preovulatory follicles during growing phases (P < 0.05) and a greater plasma estradiol concentration (P < 0.05) in this group than in the classical 14-day group, which suggest these are more functional preovulatory follicles. In conclusion, therefore, the use of the FGA7-PG treatment may favor efficiency of progestagen-based protocols for reproductive management.