AVALIAÇÃO DA TAXA DE PRENHEZ EM FÊMEAS BOVINAS SUBMETIDAS À INSEMINAÇÃO ARTIFICIAL EM TEMPO FIXO

Abstract

This study was conducted during the 2023/2024 breeding season, monitoring a total of 7,938 female cattle subjected to Fixed-Time Artificial Insemination (FTAI) protocols on several properties and in different states (Goiás, Minas Gerais, and the Federal District). The objective was to evaluate the reproductive performance of different categories of female cattle (heifers, primiparous, single, and multiparous), identifying which group presents better pregnancy rates and the physiological factors that influence these results. In addition, the study compared the efficacy of puberty induction protocols in heifers, analyzing the use of injectable progesterone in relation to the intravaginal implant. Another aspect evaluated was the influence of the application of GnRH as an ovulation inducer on the day of artificial insemination, comparing the pregnancy rates between cows that received or did not receive this hormonal intervention. The hormonal protocol consisted of the application of estradiol benzoate and insertion of an intravaginal progesterone device (D0), followed by removal of the device with administration of estradiol cypionate, eCG and prostaglandin (D7 or D8), ending with artificial insemination on D9 or D10. During management, data were collected on signs of estrus, protocol used, puberty induction and use of GnRH. Pregnancy diagnosis was performed 30 days after insemination. No category presented a pregnancy rate greater than 50%, with the highest rates observed in heifers and primiparous cows (49.7%) and the lowest in single cows. Female cattle that did not receive GnRH presented a higher pregnancy rate (52.61%) compared to those treated with the hormone (47.03%). No significant difference (P>0.05) was observed between the methods of puberty induction in heifers. The results obtained contribute to the improvement of reproductive strategies, promoting greater efficiency in management and better productive performance of herds.