Veterinarija ir Zootechnika

This study aimed to determine selected reproductive parameters, including estrus synchronization response, pregnancy rate, and prolificacy, in Bulgarian local goats subjected to estrus synchronization and artificial insemination (AI) with frozen semen during the breeding season. The investigation was carried out on 101 lactating Bulgarian local goats during the breeding season. Estrus synchronization (ES) was performed using intravaginal sponges containing 60 mg medroxyprogesterone acetate for 14 days, followed by an intramuscular injection of 500 IU PMSG (pregnant mare serum gonadotropin) on the day of sponge removal. The response to synchronization was assessed based on changes in the vaginal appearance. A single artificial insemination with frozen semen was conducted 48–52 hours after sponge removal. Pregnancy diagnosis was performed on day 35 after AI. Based on ultrasound pregnancy diagnosis and kidding data, pregnancy rate (PR) and prolificacy were recorded. The registered estrus synchronization response, pregnancy rate, and prolificacy were 100%, 22.7%, and 108.6%, respectively. In conclusion, the applied estrus synchronization protocol and artificial insemination with frozen semen during the breeding season provided acceptable pregnancy rates and prolificacy in Bulgarian local goats, particularly when the primary objective is acceleration of genetic progress in the flock. Further investigations into factors affecting the success of these assisted reproductive technologies are necessary to improve their efficiency.