Effect of the dose of FSH in gonadotrophic superstimulation on superovulatory response and in vivo production of embryos in Santa Inês ewes

Abstract

The objective of this study is to evaluate the effect of the dose of exogenous FSH in gonadotrophic treatment on the superovulatory response and in vivo production of embryos in sheep. Twenty four Santa Inês ewes will submit to estrus synchronization with an intravaginal device of progesterone (CIDR ®) that will be inserted on day 0 and will remain till the day 8. Associated with the start of the protocol and removal of intravaginal device will be administered 37.5 ¼g of an analogue of PGF2± (Prolise ®). The gonadotrophic treatment will start 48 hours before the removal of progesterone (D6) while females are randomly divided into three groups according to the total dose of exogenous porcine FSH: G200 (control, n = 8) - 200 mg of FSH; G133 (n = 8) - 133 mg of FSH, and G100 (n = 8) - 100 mg of FSH. The total doses will be administered in eight applications at 12 hour intervals (20, 20, 15, 15, 10, 10, 5 and 5% FSH). In D6 (1st application of FSH) the females will also receive 300 IU of eCG. Conventional ultrasonographic evaluations (B-mode) and Doppler (two dimensional and three dimensional) will be performed in order to accompany the growth of the ovulatory follicular wave, vascularization of the follicular wall (vascular volume and characteristics of vessels) and the time of ovulation. Six days after natural matings, the embryos will be collected and evaluated morphologically and regarding the percentage of apoptotic cells. Statistical analyzes will be performed by SAS software version 9.2 and the level of significance is P <0.05. (AU)