Effect of two different estrus synchronization protocols on pregnancy rate in Blonde D'aquitaine cattle breed reared in Bulgaria

In the study, two protocols for synchronization of estrus and ovulation in seventeen Blonde d’Aquitaine cows reared in Bulgaria are presented. The animals were similar in age (5-6 years), physiological status (non-pregnant with weaned calves, more than 210 days post-calving), and body condition score (average 5 on a 9-point scale). The experiment was conducted on a beef cattle farm near the Danube River at the end of the grazing season. The objective was to investigate the pregnancy rates under different estrus synchronization schemes. Two synchronization schemes with artificial insemination (FTAI – 72 hours) at fixed time were applied. The schemes were based on prostaglandin F2 alpha (PGF2α) and Gonadotropin-Releasing Hormone (GnRH), with one of them using а Progesterone Releasing Intravaginal Device Delta - PRID DELTA. After executing the two protocols, 47.92 ± 12.34% of the Blonde d’Aquitaine cows were confirmed to be pregnant. In the synchronization protocol using PRID DELTA 62.50 ± 17.87% of inseminated cows were pregnant. In the protocol without the device, 33.33 ± 16.94% of inseminated cows were confirmed to be pregnant. Keywords: beef cattle, estrus synchronization, PRID-Synchprotocol