Effect of acute heat stress on the physiological and reproductive parameters of broiler breeder hens – A study under controlled thermal stress

Abstract

A study was conducted to find out the effect of thermal stress on the physiological as well as reproductive performances of broiler breeder hens. The birds were exposed to 37±1°C and RH 70% for 6 hours daily for a period of 10 days in the psychrometric chamber (THI >90). In the heat exposed group, body weight gain and feed intake (P lee than 0.05) were negatively affected, whereas water consumption and water:feed intake ratio were much higher during the period of study. Even after 12hrs of heat exposure, surface temperature of feathered regions; neck and back were significantly high (P less than 0.05). The serum cholesterol level in heat treated birds was increasing (P less than 0.05), whereas calcium and phosphorus levelswere showing lower values (P less than 0.05) on the 3rd and 10th day of study. A significant change in serum protein or glucose could not be observed. The reduction in HDEP and internal egg quality parameters like albumen index, Haugh unit score, yolk index etc. were observed in heat exposed hens (P less than 0.01). Higher incidence of blood spots were also noted in eggs laid by heat treated birds. In the present study, it can be concluded that thermal stress at THI>90 for at least 6hrs/day can impart serious damage to various physiological and reproductive performances in broiler breeder hens.