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Detrimental Effect of Long Term Progestin-based Protocol on Oocyte Quality and Embryonic Development in Indigenous Goats
Long term progesterone treatments for estrus synchronization have been associated with a lesser fertility in ruminants. This experiment was conducted to determine the effects of short term (7 days) and long term (14 days) progestin based and pregnant mare serum gonadotropin (PMSG) administration on number of follicles, oocyte quality, and embryonic development in goats. Nulliparous Thai-native goats (n = 36) were randomly assigned into short term and long term protocols. Goats in the short term protocol were inserted with intravaginal sponges containing 60 mg medroxyprogesterone acetate (MAP; Synchrogest esponjas®, Spain) for 7 days. Goats in the second group were inserted with the same synthetic progesterone for 14 days. Multiple follicular development was induced by intramuscularly injections of 300 IU PMSG (Synchrogest PMSG®, Spain) in both groups on day 6 or day 13 (1 day prior to sponge withdrawal). Ovariectomy was performed at 24 h after sponge removal to evaluate number of follicles and collect oocyte for in vitro fertilization (IVF). Oocyte quality was determined by morphology of cumulus oocyte complex before in vitro maturation (IVM) as healthy or nonhealthy oocyte. After IVF, embryo was evaluated during the 8-days culture as numbers of cleaved oocyte, morula and blastocyst embryo. Total numbers of follicles and oocytes were similar for both treatments. Plasma progesterone concentrations were not different during MAP insertion period (P > 0.05). However, goats that received the short term protocol had greater number of follicles 4-6 mm, number of healthy oocytes, number of cleaved oocytes and number of morula embryos than goats received the long term protocol (P< 0.01). These data highlight the detrimental effect of long term progestin-based protocol on oocyte quality and embryonic development in goats.
Keywords: Synthetic Progesterone, Oocyte Quality, Indigenous Goat