Estrous synchronization in beef animal under the Egyptian condition \

الملخص EN

This work aimed to evaluate different protocols for estrous synchronization on beef cattle to decrease the period of calving interval and to decrease the cost of breeding by using different way of estrous synchronization to determine the best protocol used in synchronization in Egypt.

In this research, we used 102 beef (Angus, Herford and their crosses) cows and heifers 51 cows (21suckling cows ,30 non lactating cows) all cows are cycling 60days after parturition and 51cycling heifers age above 1.5 years and 10 bull for mating divided into 5 groups.

first group (GnRH-CIDR- PGF2α) second group (CIDR- PGF2α) third group(G-P-G) forth group (PG-PG) and the fifth one is a control group.

The best result is the third group with a percent of 61.1% then the second and forth group with 50% then the first group with40% and the last one is the control one with 27.8%.

From this work we concluded that the simple protocol of estrous synchronization in Egypt which is Receptal–Lutalase–Receptal (G-P-G) is the best protocol to use in this experiment