The aim of this study was to determine of pregnancy rate when Estradiol Benzoate (EB) used in presynch method than to routine presynchronization protocol in lactating dairy cows (N: 210). In this study, cows divided in two treatment groups: control group (N: 100) and main group (N: 110). Control group cows received two injections of Cloprostenol (750 μg/Case, IM) with 14 d interval. Then, they received an injection of Gonadorelin (100 μg/Case, IM), 7 d after cloprostenol (750 μg/Case, IM) injected, followed by an injection of Gonadorelin (100 μg/Case, IM) 48 h later, finally cows artificial inseminated (AI) 1618 h later. In main group, cows received an injection of EB (1 mg/Case, IM) instead of last injected Gonadorelin 24 h after cloprostenol injection. In main group, AI performed 48 h after EB injection. Detection of cow pregnancy performed at 42±3 d via rectal palpation. Estrus rate in control and main groups were 63 and 71%, and pregnancy rate were 44 and 41.1%, respectively. Also, pregnancy rate in estrus and non estrus cows compared in two groups that in control group were 44.4 and 43.2%, and in main group were 43.4 and 35.5%, respectively. Overall, no significant differences were detected between two synchronization methods in present study. In conclusion, Estradiol Benzoate can be use as a suitable instead to GnRH in presynch protocol.
25 - 29 Apr 2009
European Society of Endocrinology