Incidence of Abnormal Corpus Luteum in Superovulated Ewes

Abstract

Abstract. In the present study, in order to investigate the incidence time of abnormal corpus luteum (CL) in superovulated ewes, CL formation was observed and plasma progesterone (P4) and estradiol-17β(E2) profiles were investigated during the non-breeding and breeding seasons in three breeds of ewes. The ewes were treated with a fluorogesterone acetate (FGA) sponge for 12 days, and a single injection of 20 mg pFSH on Day -2 and 500 IU eCG on Day -1 (FGA sponge removal: Day 0), for estrous synchronization and superovulation. All ewes were given an injection of 100 µg gonadotropin releasing hormone analogue (GnRH analogue) at estrous detection and inseminated with frozenthawed semen by laparoscope on a fixed-time basis (32-36 h after FGA sponge removal). On Day 6.5, the ewes were laparotomized for ovarian response and embryo recovery. Blood was taken from all ewes on Days 0 to 6.5, and the plasma P4 and E2 concentrations were measured by emzyme immunoassay (EIA). According to the ovarian responses on Day 6.5, the ewes were divided into Group N (only normal CL; n=21), Group A (only abnormal CL; n=7) and Group M (both normal and abnormal CL; n=3). The mean P4 profile in Group N continued to rise during the period of blood sampling, and was significantly higher than in Group A which remained under 1 ng/ml and decreased after Days 4 to 4.5. The means E2 levels tended to be higher in Group A than in Group N. In the autumn study, the ewes with abnormal CL on Day 6.5 had already lacked in color on Day 4.5, and the number of large follicles was significantly lower in the ewes with abnormal CL than in those with only normal CL. These results indicate that the phenomenon of abnormal CL formation at 3-3.5 days after estrus is not due to premature luteal regression of functionally complete CL, but to luteal hypoplasia of incomplete CL with a short lifespan, but the cause of abnormal CL was not determined in the study.

Luteal lifespan and fertility after estrus synchronization in goats

“…We observed abnormal CL and a short cycle in the treatment phase during both seasons. This result is similar to that reported by Okada et al [21]. The present study has shown that the P 4 in two goats showing the short cycle decreased to basal levels (0.28 ng/ml) on day 4.…”

Early luteal development in Santa Inês ewes superovulated with reduced doses of porcine follicle‐stimulating hormone

“…It is suggested that the use of higher doses of FSH may lead to the persistence of luteinized anovulatory follicles, which continue to produce oestrogen during the early luteal phase and promote the early release of PGF2α and luteal regression (Okada et al, ). However, in the present study no greater number of anovulatory follicles were observed in the G200 in relation to the other groups.…”

“…It is suggested that the use of higher doses of FSH may lead to the persistence of luteinized anovulatory follicles, which continue to produce oestrogen during the early luteal phase and promote the early release of PGF2α and luteal regression (Okada et al, 2000).…”

“…Because, high doses of FSH may induce changes in ovarian and/or endocrine dynamics (Kafi & McGowan, ) and on LH pulses, increasing the incidence of PRCL (Bevers, Dieleman, Blankestein, Tol, & Broek, ; Oliveira et al, ) besides being more expensive (Loiola Filho et al, ). Furthermore, higher doses may maintain the stimulus of the luteinized anovulatory follicles for longer periods, so these follicles are still producing oestrogen in the early luteal phase, causing persistence of high concentrations of this hormone, providing the early release of PGF2α and thus premature luteal regression (Okada et al, ).…”

“…Furthermore, higher doses may maintain the stimulus of the luteinized anovulatory follicles for longer periods, so these follicles are still producing oestrogen in the early luteal phase, causing persistence of high concentrations of this hormone, providing the early release of PGF2α and thus premature luteal regression (Okada et al, 2000).…”