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Comparative Efficacy of Estrus Induction Protocols Using PGF2α Alone Versus OvSynch and Select Synch in Dairy Cattle
Boucif Ahmed1,2, Nouia Abdelmadjid1,2, Nabi Mustapha3
1Institute of veterinary Sciences, University of Tiaret, Tiaret, Algeria.
Introduction:
The objective of this study is to evaluate the efficacy of estrus induction protocols based on prostaglandin F2α (PGF2α), compared with an OvSynch-type variant and the Select Synch protocol, in terms of reproductive performance in dairy cows in Algerian farms.
Materials & Methods:
A total of 105 gyneco-clinically intact cows, aged 2 to 5 years, including 39 primiparous and 66 multiparous cows of Montbéliarde (66) and Holstein (39) breeds were divided into three groups. In the first group, cows received two injections of PGF2α at an 11-14-day interval, with a dose of 25 mg per cow of dinoprost®. In the "OvSynch" and "select synch" groups, cows were treated with an injection of 100 μg gonadotropin-releasing hormone (GnRH) (cystorelin®) on day 0, followed by an injection of 25 mg PGF2α (dinoprost®) on day 7. Only the "Select Synch" group received a second injection of 100 μg GnRH on day 9. Cows were inseminated based on observed estrus at the end of each protocol. Pregnancy was diagnosed via ultrasound at day 30 post-AI and confirmed by trans-rectal palpation on day 45.
Results:
Estrus response rates were 74%, 48.6%, and 40%; P>0.05), while average pregnancy rates were 54.4%, 31.4%, 28.6% (P<0.005, corresponding to conception rates of 73.1%, 65%, and 71.4% (P>0.005) for groups 1, 2, and 3, respectively. Given its simplicity, cost-effectiveness, and efficiency, the prostaglandin-only protocol is recommended for cows inseminated based on observed estrus.
Conclusion:
Protocols combining GnRH with PGF2α allow estrus synchronization, reducing the need for daily estrus detection (EI) and additional handling.
