Fatores associados à taxa de prenhez pós-transferência De embriões bovinos em condições de campo

Abstract

ABSTRACT Introduction: Embryo transfer (ET) is an essential biotechnology in bovine reproduction, boosting productive efficiency and genetic progress in herds. Understanding the factors that impact pregnancy rates, such as cryopreservation, reproductive management, and genetic characteristics, is crucial to maximize reproductive performance in commercial production systems. Objective: To evaluate the factors associated with pregnancy rate at 30 days post-embryo transfer (P30) in bovine recipients subjected to in vitro-produced embryo transfer, considering embryo type, semen type, donor and sire breed, embryonic stage, and corpus luteum functionality. Methodology: This was an observational and descriptive study conducted in a bovine reproductive biotechnology laboratory located in Goiânia, Goiás, Brazil, between January and February 2026. A total of 180 embryo transfer procedures were retrospectively analyzed. Animals not evaluated at P30 were excluded from the

analysis. Data were subjected to descriptive and inferential analyses using the Chi- square test and Fisher’s Exact Test (p<0.05), considering limitations arising from

sample imbalance among groups. Results: Fresh embryos showed a higher pregnancy rate (40.3%) compared to cryopreserved embryos (25.0%), although the difference was not statistically significant (p>0.05). Conventional semen showed similar performance to sexed semen, with no statistical difference between groups. Recipients classified in the D1 and E1 categories showed higher pregnancy rates compared to other corpus luteum classifications. Regarding genetic factors, variation in pregnancy rates was observed among donors and sires, without a consistent pattern of superiority among the evaluated groups. Conclusion: The efficiency of embryo transfer under field conditions is influenced by multiple factors, with embryo type being the factor that demonstrated the largest numerical difference in pregnancy rates, highlighting the need for strict embryo and recipient selection, as well as standardized management protocols.