Effects of heat stress on some physiological parameters in crossbred dairy cows raised in Nghia Dan district, Nghe An province

Abstract

An experiment was conducted to determine effects of heat stress on some physiological parameters in crossbred dairy cows F₁ (50% HF) and F₂ (75% HF) in the summer season in Nghia Dan district, Nghe An province. Results showed that the temperature-humidity index (THI) was always high. THI was always higher inside (75.15-83.96) than outside (75.81-84.33). Therefore, the cows were always under stressful conditions. Heat stress significantly affected physiological parameters. When THI increased body temperature, pulse rhythm and respiration rate were increased. THI had positive correlations with those physiological parameters.