Factors affecting number of surface ovarian follicles and oocytes yield and quality in egyptian buffaloes

(Received 5 September 2000; accepted 29 December 2000)

Abstract
Three experiments were conducted to evaluate factors affecting number of surface ovarian follicles and oocytes yield and quality in buffalo. In Experiment 1, ovaries (n = 126) were collected in pairs from slaughtered anoestrus, early pregnant and cyclic buffaloes. Ovarian follicles (1-3, 4-9 and 10 mm diameter) were counted, aspirated and oocytes were recovered and evaluated. In Experiment 2, ovaries were divided into 2 groups. Group 1, ovaries bearing a CL (n = 74) and Group 2 non-bearing CL (n = 74), ovarian follicles (2-8 mm) were counted, aspirated and oocytes evaluated. In Experiment 3, oocytes were recovered using aspiration or slicing methods. In all experiments, oocytes were classified into good, fair, poor and denuded. Results showed that the development of small and total ovarian follicles are continuous and independent in early pregnant or cyclic buffalo cows, however, it significantly decreased ( P < 0.01) in the ovaries of anoestrus buffaloes. Number of medium and large size follicles was significantly increased ( P < 0.01) in cyclic buffaloes on Days 10-16 and 17-22 of oestrous cycle, while large follicles was significantly decreased ( P < 0.01) in the ovaries of pregnant buffaloes. A significantly higher ( P < 0.01) percentage of poor and denuded oocytes were recovered from ovaries of anoestrus and pregnant buffalo. While, the highest ( P < 0.01) percentage of good quality oocytes were recovered from ovaries of cyclic buffaloes on Days 1-3 and 10-16 of oestrous cycle, eliciting that the stage of oestrous cycle is affecting the quality of buffalo oocytes. In addition, the presence of a CL stimulates the development of a significantly higher ( P < 0.01) number ovarian follicles which produced a significantly higher ( P < 0.05) number of good quality oocytes. Slicing of buffalo ovaries produced a significantly higher number of fair, poor and denuded oocytes. In conclusion, number of ovarian follicles and yield and quality of oocytes were affected by the reproductive status, stage of the oestrous cycle, presence of a CL and the method of oocytes retrieval.