Effects of heat stress on growth performance, physiological responses, and carcass traits in broilers

High environmental temperatures lead to metabolic changes, body weight reduction, and high mortality in chickens, affecting poultry production worldwide. This study aimed to evaluate the effects of heat stress, assessed by the temperature–humidity index (THI), on the growth performance, physiological response, carcasses, and hematological traits of broilers. A total of 200 broilers (between 17 and 31 days old) were kept in thermoneutral conditions (21 °C; 60% relative humidity, RH) for 3 days during the adaptation period, followed by 14 days of exposure to the experimental treatments. The broilers were randomly assigned to 4 groups of equal size and raised in a temperature–humidity controlled chamber with THI ranging from 67 (21 °C; RH 60%) to 84 (33 °C; RH 60%). In boilers subjected to severe heat stress (THI 84), feed intake (−30%) and body weight gain (−51%) were decreased (P