Ovarian follicular dynamics, hormonal profiles and ovulation time in Mithun cows (Bos frontalis)

The study aimed to evaluate follicular dynamics and concentrations of estradiol‐17β (E2), progesterone (P4), follicle stimulating hormone (FSH) and luteinizing hormone (LH) during the oestrous cycle and to determine ovulation time in Mithun cows. Ovaries of experimental cows (n = 7) were examined daily by transrectal‐ultrasonography for three consecutive oestrous cycles (n = 21). The characteristics of follicular waves, dominant follicle, largest subordinate follicle and corpus luteum and ovulation time were evaluated. The plasma samples were analysed throughout the interovulatory interval to determine the differences in the hormonal profiles (E2, P4, FSH and LH) between different follicular wave cycles. Out of eighteen oestrous cycles analysed, three‐wave follicular cycles were maximum (n = 12: 66.66%) followed by two (n = 4: 22.22%) and four waves (n = 2: 11.11%). The two and three waves were statistically compared, and no significant (p > .05) differences were observed in day of wave emergence, number of follicles (≥3 mm) recruited, maximum diameter of the ovulatory dominant follicle, growth rates of ovulatory and anovulatory dominant follicles and maximum diameter of corpus luteum. The diameter of dominant follicles was significantly (p