Ovarian function in the buffalo and implications for embryo development and assisted reproduction

This review brings together information on ovarian physiology in buffaloes including folliculogenesis, ovulation, and the development and function of the corpus luteum. Features of embryonic development are also considered. The buffalo is classified as a short-day breeder but in equatorial zones can show oestrous cycles throughout the year provided that nutrition is adequate to maintain reproductive function. In sub-tropical zones and at higher latitudes, day length is often the major determinant of reproductive function including the occurrence of regular oestrous cycles, duration of oestrus, and the period to resumption of ovulation postpartum. Indeed, at higher latitudes buffaloes that give birth during the period of increasing day length may not show a resumption of ovulation until the following period of decreasing day length. This can have a major impact on the productive value of buffaloes and requires the development and utilisation of practical and effective assisted breeding technology for out-of-season breeding in buffaloes. Embryonic development in buffaloes occurs at a faster rate than in cattle and this has implications for the earlier establishment and functionality of the corpus luteum in buffaloes. It would appear that the interrelationships between the development of the early conceptus, corpus luteum function, uterine preparation, and maternal recognition of pregnancy, are more closely time-bound in buffaloes compared with cattle. The phase of embryonic attachment would seem to be a critical period for determining the reproductive outcome in buffaloes.