Postpartum uterine involution and ovarian changes in Chinese crossbred buffaloes

This study assessed postpartum uterine involution and its influential factors (season, milk production, breed, age, body condition score; BCS, and body weight; BW) along with ovarian activity resumption in Chinese crossbred buffaloes (CCB). Sixty-two freshly calved CCB underwent ultrasound monitoring for postpartum uterine involution and factors like season, milk yield, breed, BCS, BW, and parity were considered. In another group of 22 CCB, daily ultrasonic monitoring tracked follicular and luteal dynamics from day 7 to day 56 post-calving. The period of involution for the cervix, gravid, and non-gravid horn was 33.5 ± 4.1, 34.4 ± 6.1, and 31.5 ± 5.3 days, respectively. Uterine involution time was influenced by breeding season, milk yield, and age but not by breed, BCS, parity, or body weight. The first and second postpartum ovulation occurred at 40.6 ± 11.0 and 57.3 ± 10.0 days after calving, with 77% and 59% occurring ipsilateral to non-gravid horns. Significant differences were noted in oestrus expression, ovulatory follicle size, and ipsilateral ovulation in non-gravid horns. Follicular patterns maintained consistent ovulatory follicle sizes with varying cycle durations. Ovarian activity resumes by the 6 to 7th weeks post-calving. Timely involution and ovarian activity are crucial for postpartum reproductive activity in buffaloes. These insights enhance fertility rates with reproductive-assisted technologies in buffaloes.