Follicular dynamics and changes in estradiol-17β, progesterone and LH profiles following PGF 2α induced estrus in early and late ovulating Beetal goats.

This study compares the factors associated with variable interval to estrus and ovulation between early vs. late ovulating goats following PGF2α administration. The extent of ovulation time in Beetal goats (n = 38) was monitored through transrectal ultrasound at every 6 h following a single dose of PGF2α  (experiment 1). Variation in estrus and ovulation times was further explored through the changes in follicular dynamics, endocrine profiles and behavior in another set of goats (n = 13) following single PGF2α  given randomly during the luteal phase (experiment 2). The ovulation time varied between 60 to 96 h and 57% of ovulations occurred by 72 h following PGF2α  (experiment 1). Accordingly, the goats (n = 13) in the second experiment were retrospectively divided either into early and/or late ovulating i.e., ≤ 72 and/or ≥ 84 h following PGF2α .  The onset of estrus, peak estradiol-17β concentration and LH surge after PGF2α  was first observed in early than late ovulating goats (P < 0.05). The goats ovulating early had larger follicle and smaller CL in diameter at the time of PGF2α administration than those ovulating late (5.4 ± 0.2 vs. 4.3 ± 0.2 mm and 10 ± 0.6 vs. 11.8 ± 0.3 mm, respectively; P < 0.05). Likewise, plasma progesterone concentration tended to be lower (P = 0.087) in early than late ovulating goats. In conclusion, the size of dominant follicle and CL at the time of PGF2a  determines the interval to ovulation following a single dose of PGF2a  during the luteal phase. This article is protected by copyright. All rights reserved.