Intrauterine Chitligsan administration in postpartum Simmental cows: Effects on uterine artery hemodynamics, endometrial cytology, ovarian follicular dynamics, and fertility.

This study investigated the effects of intrauterine administration of 40% Chitligsan (CHT) on postpartum day 30 on uterine hemodynamics, follicular dynamics, endometrial cytology, cervical involution, and reproductive performance in clinically healthy multiparous Simmental cows. Twenty-one cows were assigned to the CHT (n = 14) or control (CON, n = 7) groups. Doppler ultrasonography, ovarian examination, cervical measurements, and cytological assessments were performed on postpartum days 9, 15, 30, and 40, and treatment was administered immediately after the day 30 assessments. On postpartum day 40, resistive index and pulsatility index were higher in the CHT group than in the CON group (P < 0.05), accompanied by numerically lower blood flow velocities and a time-dependent reduction in uterine artery diameter. Total antral follicle count remained stable over time in the CHT group, whereas significant changes were observed in the CON group between days 15-30 and 30-40 (P = 0.031). Weighted mean follicle diameter decreased significantly from day 30 to day 40 only in the CHT group (P = 0.011). In endometrial cytology, PMNL proportion was lower in the CHT group on postpartum day 40 (P = 0.019), whereas epithelial cell proportion tended to be higher (P = 0.069). Although pregnancy rate based on the first two inseminations was numerically higher in the CHT group, the difference was not statistically significant. In conclusion, intrauterine CHT administration was associated with a consistent Doppler and cytological profile suggestive of enhanced uterine recovery, with no apparent adverse effect on ovarian follicular dynamics.