ESTRESSE TÉRMICO CALÓRICO UMA AMEAÇA SILENCIOSA À FERTILIDADE DE VACAS LEITEIRAS

Abstract

Abstract:

Dairy farming is a strategic sector in Brazil, responsible for meeting the growing global demand for high-quality protein. However, the impact of heat stress (HS) in tropical and subtropical regions significantly compromises the productivity and reproduction of dairy cows, leading to lower pregnancy rates and increased embryonic losses. This study evaluated the relationship between HS and the reproductive efficiency of dairy cows on a farm located in Riqueza, SC, during the period from February to October. The results of Fixed-Time Artificial Insemination (FTAI) protocols performed on 43 Holstein and Jersey cows under different climatic conditions were analyzed. The average maximum temperatures during the protocols ranged from 24°C to 33°C, with corresponding pregnancy rates of 33.33% (February), 29.41% (April), 66.67% (June), and 100% (August). A negative correlation was observed between high temperatures and conception rates, highlighting the influence of HS on reducing oocyte quality, embryonic viability, and hormonal efficiency. The farm’s inadequate infrastructure, including the lack of ventilation, shading, and limited water access, worsened the effects of HS. Mitigation strategies, such as sprinklers, ventilation, and shaded areas, were recommended to improve thermoregulation and reproductive efficiency. This study underscores the importance of management practices to reduce the impacts of HS, promoting greater sustainability in dairy production in hot regions.

Keywords: Heat Stress; Reproductive Efficiency; Embryonic Losses.