Evaluation of environmental parameters in a microregion in southern Amazonas State, Brazil, and their relationship with heat stress in dairy cattle

Abstract Environmental thermal comfort provides higher efficiency in the exploitation of dairy farming, as responses animals to environment are decisive activity’s success. This study aimed evaluate heat stress cows municipality Humaitá, located south theAmazonas State (AM), Brazil.Air temperature (TA) and relative humidity (RH) data were used calculate index (THI) dry (August 2020) rainy seasons (January 2021). The August collected at automatic weather station belonging National Institute Meteorology. January by a Hobo® U23-001 thermo-hygrometer installed Fazenda Nossa Senhora Aparecida. hourly monthly means calculated and, subsequently, boxplots plotted. TA RH 0.65 °C 0.64% below provisional climatological normal (PCN), respectively, for August, while presented 0.77 3.61% above PCN, respectively. THI values ranged from 56.25 (comfortable) 84.68 (emergency) 74.15 84.07 January. maximum was observed well largest range. results allow inferring that Humaitá-AM presents state alert even cross-breed animals. Thus, use shading pastures is suggested minimize effect on productive performance