Reproductive efficiency is the primary factor affecting productivity of farm animals. Among the various causes of subfertility, anoestrus is the major reproductive disorders (Pandya et al., 1989). Prolonged postpartum acyclicity and anestrum are major sources of economic loss to buffalo breeders (El-Wishy, 2007). Postpartum ovarian activity and subsequent pregnancy may be affected by several factors such as breed, nutrition plan, milk yield, suckling, uterine involution, season of calving (Arya and Madan, 2001; Baruselli et al., 2001; Campo et al., 2002). The present study was conducted to explore the cyclical status of apparent anoestrus postpartum buffaloes and to test the effectiveness of oestrus induction in cyclic and non-cyclic buffaloes at 60 or more days post-partum. Pre-ovulatory follicle (POF) is the prime structure behind the endocrinology of oestrus in buffaloes which produces substantial amounts of estradiol. The present study was conducted to investigate the relationship of pre-ovulatory follicular (POF) diameter at estrus with subsequent luteal size and pregnancy in buffaloes.
