Synchronization of follicular wave emergence following ultrasound-guided transvaginal follicle ablation or estradiol-17β administration in water buffalo (Bubalus bubalis)

The aim of this study was to assess the synchrony in follicular wave emergence and subsequent ovulation following dominant follicle ablation or estradiol-17β administration. Six cycling Murrah buffaloes were sequentially allotted to three groups, that is, control, follicular ablation, and estradiol-17β groups. For the control group, buffaloes at random stages of estrous cycle were examined daily by transrectal ultrasonography for 14 days and the day of wave emergence was recorded. Following induced luteolysis and ovulation (Day 0), these buffaloes were included in the ablation group. All follicles (>5mm) were ablated on Day 3 or 5 or 7 (n=2 each day). Seven days after the ablation, these buffaloes were administered prostaglandin F2α to induce luteolysis and ovulation. Following this, buffaloes were included in the estradiol treatment group with estradiol administered on similar days as for ablation in the ablation group. Luteolysis was induced nine days after the estradiol injection. All animals of the treatment groups were subjected to transrectal ultrasound and blood samplings daily from treatment to induced ovulation. The follicular waves emerged significantly earlier (P=0.001) in both the ablation (2.1±0.79 days) and estradiol (4.0±0.25 days) treatment groups than the control group (8.3±0.88 days). The deviation from mean day of ovulation was greater (P=0.02) for the control group buffaloes (1.66±0.3 day) than those of the treatment groups (ablation, 0.76±0.2 and estradiol, 0.58±0.2 day). In conclusion, both ablation and estradiol resulted in synchronous emergence of a new follicular wave irrespective of stage at which the treatment was given, with greater synchrony of ovulations in water buffalo.