Postpartum uterine involution and ovarian follicular dynamics in crossbreed Anatolian water buffalo (Bubalus bubalis) during summer season

It was aimed to monitor postpartum (pp) uterine involution and follicular wave pattern by transrectal ultrasonography and detection of concentrations of milk progesterone (P 4) in eleven water buffaloes during the summer season in Turkey. The data obtained from the first day of calving to positive pregnancy diagnosis were evaluated on a daily basis. Uterine position scores and nonechogenic material showed a decreasing grade pattern related to the time (P < 0.0001). A time effect was evident with uterine horn thickness (P < 0.05) or intercaruncular zone thickness (P < 0.01) and uterine horn lumen (P < 0.01). Uterine horn thickness showed a gravidity x time interaction (P < 0.05). Gravidity x time interaction was not evident in total uterine horn thickness but time effect was seen (P < 0.0001). Time effect was also evident for the thickness of uterine body (P < 0.0001) and cervix uteri (P < 0.01). The uterine body and horns were returned to previously nongravid state on day 26.00 +/- 2.38 and the interval from calving to complete disappearance of uterine fluid was accomplished on day 31.44 +/- 3.23 pp. The previously gravid and nongravid uterine horns, uterine body and cervix uteri involuted on day 31.42 +/- 1.39, 28.37 +/- 0.65, 29.37 +/- 0.73 and 27.87 +/- 0.47 pp, respectively. The interval from calving to first observation of dominant follicle of nonovulatory wave was 18.54 +/- 6.91 days and on average 3.45 +/- 1.91 nonovulatory waves were observed. Postpartum first ovulation occurred on day 64.45 +/- 18.49. One and two wave models or combination of both waves were observed. The interval from calving to pregnancy was 72.36 +/- 21.33 days. The maximum concentrations of milk P 4 during short or normal cycles and pregnancy were 0.62 ng/mL, 2.2 ng/mL, and 4.04 ng/mL, respectively. In conclusion, the presence of one or two waves should be considered when estrous synchronization programmes are planned in Anatolian water buffaloes during summer season.