Follicular and luteal dynamics of buffalo (Bubalus bubalis) during breeding and non-breeding seasons

This study aimed to assess ovarian follicular and luteal dynamics of Buffalo (Bubalus Bubalis) during breeding and non-breeding seasons. The study was conducted in the Equatorial Amazon (4o Latitude South, State of Maranhao, Brazil). Reproductive seasonality has not been assessed in the region of the study. Based on records of conceptions/births from the previous three years, a reproductive favorable season (FAV; July 2013) and an unfavorable season (UNFAV; January 2013) were determined. Twenty two multiparous nonlactating Murrah female buffaloes (Bubalus bubalis), with average body score 3.25±0.6 (Ranging 1 to 5) and bearing at least one follicle ≥ 8.5mm denoting ovulatory capacity were used. The same buffaloes were evaluated in both periods (january and july) and treated with two doses of PGF2alpha with a 14 day interval (0.50 mg of Cloprostenol, Sincrocio®, IM; Ouro Fino, Brazil). Ovarian dynamics was monitored daily starting 48 hours after the second dose of PGF. Jugular blood samples from all animals were collected daily to measure serum progesterone concentrations. Parametric variables were analyzed by ANOVA using SAS®. Breeding seasons and follicular waves were compared using Student's t test (PROC GLM). Hormonal concentrations were analyzed as repeated measures (PROC MIXED). Non- parametric variables were analyzed using the Wilcoxon test (PROC NPAR1WAY WILCOXON) and the binomial distribution by PROC GLIMMIX. The significance level was 5%. The general rate of cyclicity (presence of corpus luteum at the first PGF) differed significantly between seasons (13.6 % for UNFAV vs 72.7% for FAV, P<0.05). The presynchronization protocol was not effective in UNFAV, and was followed by anovulatory waves and turnover of dominant follicles up to 9.1 ± 0.2 mm in all animals. In FAV, only 18 females (81.8%) ovulated at regular intervals indicating occurrence of physiological estrous cycles. Of these, 15 females (83.3%) exhibited a two follicle wave pattern, two (11.1%) exhibited one follicular wave and only one (5.6%) had three follicular waves. Serum progesterone concentrations differed between UNFAV (0.9 ± 0.1 ng/mL) and FAV (7.2 ± 0.7 ng/mL) (P<0.05). Mean values for females with One vs Two vs Three follicular waves were, respectively: interovulatory interval (22.5 ± 2.5 vs 21.9 ± 0.6 vs 22.0 days), maximum diameter of the ovulatory follicle (12.5 ± 1.5 vs 12.1 ± 0.3 vs 9.0 mm), and length of luteal phase (10.5 ± 2.5 vs 13.0 ± 0.8 vs 14.0 days). In summary, the FAV period was characterized by cyclic ovarian activity with predominance of two follicular waves and the UNFAV period by turnover of anovulatory waves with persistent follicles. We concluded that nonlactating buffalo females display distinct reproductive patterns in favorable and unfavorable reprudcutive periods.