Impacto da variabilidade meteorológica das regiões tropicais úmidas do México na taxa de concepção de embriões bos indicus produzidos in vitro
DOI:
https://doi.org/10.5965/22381171e28178Palavras-chave:
transferência de embriões, estresse térmico, trópicos úmidos, índice de temperatura e umidade, corpo lúteo, vacas receptoras de embriõesResumo
A produção pecuária nas regiões tropicais úmidas do México enfrenta diversas mudanças derivadas da variação climática, particularmente o estresse térmico, medido pelo índice de temperatura e umidade (ITU), que compromete a eficiência reprodutiva. O objetivo deste estudo foi avaliar o impacto de variáveis meteorológica na taxa de prenhez (TP) de vacas receptoras de embriões (VR) para as quais foram transferidos embriões de Bos indicus produzidos in vitro (PIV). Foram analisadas 3610 transferências de embriões (2021-2024) nos trópicos úmidos. Foram mensurados a temperatura do ar, a umidade relativa do ar, a precipitação pluviométrica e os ventos predominantes, e o ITU foi calculado e categorizado (conforto, alerta, perigo, emergência). A prenhez foi confirmada por ultrassonografia trans retal (45º-50º dia) após a transferência de embriões. Foram aplicados testes χ², regressão logística e análises multivariadas (Análise de Componentes Principais, ACP). A TP global foi de 40%. De acordo com a análise anual, 2023 apresentou a maior taxa (47,9%) e as menores foram observadas em 2021-2022 (37-38%). Na análise sazonal, o inverno e o outono registraram os melhores resultados (43-44%), enquanto a estação menos favorável foi o verão (34,9%). O período seco apresentou melhores resultados do que o chuvoso (42,7% vs. 37,8%; p<0,05). Corpos lúteos grandes (CL3 ≥25 mm) estiveram associados a maior sucesso na concepção (p<0,05). A regressão logística indicou uma redução de 56,8% (THI 59,1) para 32,2% (THI 87,4) na possibilidade de uma concepção bem-sucedida. A análise de componentes principais (ACP) explicou 61,6% da variação, mostrando uma correlação negativa entre a taxa de concepção e a temperatura. A variabilidade meteorológica nos trópicos úmidos do México reduz a eficiência das transferências de embriões in vitro em condições extremas de calor e umidade. Essas descobertas fornecem uma base para o manejo sazonal e estratégias de adaptação da biotecnologia reprodutiva em climas tropicais.
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