Water buffaloes are the most important domestic animal in Egypt; they are the main source of milk where they contribute for approximately 70% of the total milk production in Egypt. Moreover, buffalo's milk is preferred by the Egyptians because of its white color, high fat content and good flavor (El-Salam and El-Shibiny, 2011). The total numbers of buffaloes in Egypt are about 4,164,928 head, with 2,650,000 ton of milk production (Hassan et al., 2017). However, buffaloes have a lower reproductive performance than cattle. This lower performance may be attributed to late maturity, long postpartum anestrus interval, poor conception rate and seasonal reproductive activity. Anestrus due to ovarian dysfunction is the major reproductive disorders in Egyptian buffaloes (Sosa et al., 2016). However, little efforts have been made to improve their genetic potentiality for productive and reproductive traits (Ibrahim, 2012)
Reproductive performance is one of the most determinant factors for dairy farm profitability. Changes of the insulin-like growth factor-1 (IGF-1) concentration after calving are important metabolic factor affecting the postpartum ovarian activity and eventually the animal’s reproductive performance (Kadivar et al., 2012). It is an endocrine hormone and has been strongly associated with several