Abstract
The objective of this study was to investigate the effect of season on the follicular and luteal dynamics and pregnancy rate in Egyptian buffaloes. A total of 327 genital tracts and 596 animals were used. The genital tracts were examined in winter (n = 58), spring (n = 179), summer (n = 49), and autumn (n = 41) for follicular population, incidence of presence of developed or mature corpus luteum (CL), and diameters of the preovulatory follicle (OF) and the mature CL. Buffaloes were mated in winter (n = 297) and summer (n = 299) and examined for pregnancy rate. Results showed that the mean number of the large follicles was higher in winter (1.21 +/- 0.08 mm) and spring (1.04 +/- 0.05 mm) than in summer (0.64 +/- 0.1 mm) and autumn (0.78 +/- 0.1 mm) (P = 0.0001). Likewise, the mean diameter of the OF was greater in winter (14.71 +/- 0.7 mm) and spring (14.36 +/- 0.5 mm) than in summer (12.4 +/- 0.8 mm) and autumn (12 +/- 0.8 mm) (P = 0.02). In addition, the mean diameter of the mature CL was higher in winter (15.8 +/- 0.4 mm) and spring (15.5 +/- 1.1 mm) than in summer (14.2 +/- 1 mm) and autumn (13.2 +/- 0.7 mm) (P = 0.003). The incidence of presence of developed or mature CL was lower in summer (69.4 %) than in winter (74.1 %), spring (87.2 %), or autumn (85.4 %) (P = 0.01). Double CLs (0.9 %) were observed only in spring. Ovarian cysts (2.5 %) were detected in winter and spring. The pregnancy rate was higher in buffaloes mated in winter (75.4 %) than in those mated in summer (61.9 %) (P = 0.0004). In conclusion, season affects the ovarian activity and reproductive efficiency of buffaloes, where winter and spring are the optimum seasons for breeding.