Comparison of the Effect on CIDR and GNRH Inducing Estrus Synchronization

【Objective】This experiment was to investigate effect of the estrus synchronization induced by CIDR and GnRH.【Method】The GnRH+PG+GNRH and CIDR+EB+P4+PG were used to induce the Estrus Synchronization of Holstein.For the CIDR group: In order to induce the ovarian follicle occurrence,CIDR was put in the vagina of the dairy cattle at any day of the estrus cycle(not the day of estrus) with 2 mgEB and 50 mg P4 intramuscular injection at the same time.After the eighth day of intramuscular injection,CIDR was put again.GnRH group and CIDR group were to induce the synchronous estrus processing at the same time: muscle injecting PG after seven days of injecting GnRH.Two days later,muscle injecting GnRH again.【Result】The estrus synchronization rate and pregnancy rate of estrus had no significant difference.【Conclusion】GnRH was easy to operate in practice and the estrus synchronization rate was a little bit higher than CIDR.