The influence of the corpus luteum on ovarian follicular dynamics during estrous synchronization in goats

Ovarian follicular dynamics and fertility are unaffected by the presence or absence of a corpus luteum during synchronization of estrus with progestins in goats. On day 5 of the estrous cycle (estrus=day 0), a gestagen-containing sponge was inserted in the vagina for 11 days. To remove corpora lutea, one group of goats (CL−, n=41) received 7.5 mg of luprostiol on days 7 and 8 of the estrous cycle. The second group of goats retained the CL (CL+, n=38). Growth and development of follicles ≥4 mm in diameter were measured daily from onset of estrus to 2 days after subsequent ovulation in seven goats from each group, using rectal ultrasonography. Estrus was detected by the use of a reproductively sterilized buck and estrous does were subsequently mated. The number of waves of follicular development (CL −=3.57±0.2 versus CL+=3.14±0.14; P>0.05) did not differ between groups. The second wave of follicular development was present at the time of progesterone decline in the CL− group and neither its duration (CL−=4.8±0.4 versus CL+=5.6±0.7 days; P>0.05) nor the day of commencement of the third wave of follicular development (CL−=11.6±0.7 versus CL+=11.8±0.6; P>0.05) were altered by the concentration of endogenous progesterone. The pregnancy rate was similar between the two groups. (CL−=68.29% versus CL+=65.79%; P>0.05). Thus, in goats, ovarian follicular dynamics and fertility were not altered by the presence or absence of a corpus luteum during estrous synchronization.