Comparison of Follicular Development and Luteal Function During Breeding and Non-Breeding Seasons in Subtropical...

Reproductive seasonality in subtropical goats is considered weak, yet seasonal differences in ovarian dynamics remain poorly characterized. This study compared ovarian follicular and luteal dynamics during breeding (September-November) and non-breeding (May-July) seasons in six multiparous Beetal goats monitored for three consecutive estrous cycles per season, (i.e., 18 cycles per season) and maintained under semi-intensive conditions. Ovarian activity in each goat was monitored daily for three consecutive cycles using transrectal ultrasonography, and progesterone concentrations were analysed to evaluate follicular wave patterns, ovulation and luteal function. The distribution of cycle types did not differ significantly between seasons (p > 0.05); however, normal cycles occurred more frequently during the breeding season as a non-significant trend (p = 0.08). Inter-ovulatory intervals were longer, and multi-wave patterns were more frequent during the non-breeding season (p < 0.05). Preovulatory follicle size (p = 0.66) and growth rate (p = 0.18) were unaffected by season, indicating conserved follicular characteristics. Corpus luteum diameter was influenced by cycle type but not season, whereas progesterone concentrations showed a significant season-by-stage interaction (p = 0.04), indicating that seasonal differences were not uniform across the luteal cycle. Double ovulations occurred only during the breeding season. These findings indicate weak but measurable seasonal modulation of ovarian function in subtropical goats, providing insights for improving reproductive management strategies.