The Productive Response of Hens Exposed to Heat Stress

Abstract

The environmental stress has been implicated in adverse marked effects on egg production and eggshell quality of hens. The effect of heat stress was studied on three hen breeders (White Leghorn, Rhode Island, and White Plymouth Rock). The experiments were conducted on 4210 hens aged 31 weeks for each breed. The experimental period was 4 weeks. At age 32 weeks, the environmental temperature was 34.4 – 36.4°C, into the hall. There were monitored the following productive parameters: feed intake, laying rate, egg weight, and shell thickness. After one week of heat stress the feed intake decreased with 32.4% at White Leghorn females stock, 21.8% at Rhode Island and 27.3% at Plymouth Rock. After three weeks of heat exposure, the laying rate decreased with 10.4% at White Leghorn, 6.1% at Rhode Island, and 5.8% at White Plymouth Rock (p≤0.05). The egg weight decreased with 3-3.2 g to all groups. The shell thickness was lower with 0.07 mm at White Leghorn, 0.04 mm at Rhode Island and 0.03 mm at White Plymouth Rock. The lower egg quality established a decrease of eggs for incubation. White Leghorn breed was more affected by the heat exposure, because the productive parameters production had a drastic decline. In this breed, mortality was determined by cannibalism and internal haemorrhages.