Comparative Study of after Insemination Use of CIDR and GnRH in Fertility Rate Improvement in Repeat Breeder Cows

The aim of current study is to compare fertility rate improvement by using Controlled Internal Drug Release (CIDR) or GnRH (Gonadorelin) in repeat breeder cows. A total of 150 repeat breeder cows with healthy genital tract in clinical examinations were selected and divided into 3 groups of 50 cows group-1. In group 1, CIDR is used in day 5 until 12 after insemination. In group 2, an injection of Gonadorelin was done in day 11 after insemination for each cow and group 3 (control), received no treatment. The results showed fertility rate of 28, 16 and 12% in group 1, 2 and 3, respectively. There were significant differences in fertility rate between group 1 and 3 (p = 0.0092) and group 1 and 2 (p = 0.04). In conclusion, the use of CIDR is more efficient than single dose of Gonadorelin in treatment of repeat breeder cows.