Effects of intravaginal progesterone devices and Booroola fecundity (<i>FecB</i>) gene on the ovarian responses and reproductive indices of Qezel ewes following estrus synchronization and laparoscopic insemination during the breeding season

Abstract. The ovarian responses concerning types of vaginal devices in fat-tailed ewes carrying the Booroola fecundity gene (FecB) has not been studied in detail. Evaluation of the ovulatory responses and distributions following estrus synchronization with controlled internal drug release (CIDR) or a vaginal sponge in ewes carrying FecB compared to non-carriers and reproductive indices after laparoscopic insemination (LI) are the aims of the current study. Estrus was synchronized using CIDR (n=16) or medroxyprogesterone acetate (MPA) sponge (n=15) insertion (day −14) and an eCG injection on device removal (day 0). Laparoscopic insemination was performed, and the ovarian structures were measured intensively using a transvaginal probe after −14 and 0 d as well as after 36–38 and 48–51 h and continued every 4 h until 75 h after the eCG treatment. The progesterone amounts were measured in sera samples. The initiation and termination of ovulations happened earlier in CIDR-receiving ewes and FecB carriers compared to MPA-sponge-treated ewes and non-carriers, respectively (P&lt;0.05). Progesterone concentrations were higher in the CIDR group compared to MPA sponge group on day 0. Device types did not affect the sizes of ovulatory follicles, corpora lutea diameters, and reproductive indices (P&gt;0.05), while the twining rate, litter size, and reproductive rate were greater in FecB carriers compared to non-carriers (P&lt;0.05). Ovulation synchronization with MPA sponge with an eCG delayed the ovulation but did not influence the conception rate compared to CIDR-treated ewes. In spite of the smaller sizes of the ovulatory follicles and subsequent corpora lutea, higher reproductive outcomes were acquired in the FecB carriers compared to non-carrier fat-tailed ewes following LA.