Effect of shading on physiological and reproductive parameters in Nelore cows

Abstract This study aimed to evaluate the physiological and reproductive parameters of Nelore cows under different microclimatic conditions. The experiment was performed in Central Brazil, which has a tropical climate, dry winter, and rainy summer. The experimental groups were divided into an area with shading (5.8 trees/ha; n = 42) and an area with little shading (0.4 trees/ha; n = 42). We assessed physiological parameters (heart rate, respiratory rate, rectal temperature, surface body temperature, and vaginal temperature), and reproductive parameters (estrus detection, conception rate, and rate of pregnancy loss). Rectal temperature (p = 0.002), surface body temperature on the flanks, forehead, and shoulder (p < 0.001), and vaginal temperature (p < 0.001) of cows in the group with shading was significantly lower those of cows in the group without shading. Estrus was higher (p = 0.08) in the cows of the shaded group; however, no effect was observed in conception and pregnancy loss rates. In conclusion, shading (5.8 trees/ha) provided better thermal comfort for Nelore animals in this tropical climatic region. However, it did not affect the performance of fixed-time artificial insemination.