The Effects of Heat Stress on Yield and Fertility of Laying Hens and Precautions to be Taken

Abstract

High temperatures in hot regions and summer months impair the yield and productivity of laying hens. In this study, it is aimed to give detailed information about the measures to be taken to reduce the losses to the effects of heat stress on the yield and productivity of laying hens. Heat stress is one of the most challenging problems that affect all parameters of production performance and productivity, leading to high mortality rates and significant economic losses in commercial laying hens‘ production due to inhibition of immune responses. It manifests itself with neurological symptoms such as high body temperature, hot-dry skin, paralysis, headache and loss of consciousness. It causes death as a result of heat cramps and stroke. In addition, heat stress disrupts the reproductive hormones of female-male laying hens. It causes infertility in male by reducing the number and movement of viable sperm. The effect of heat stress depends on age, sex, body weight, relative humidity and length of stay at high temperature. The temperature should not exceed 24°C for optimum egg yield and quality, and 27°C for welfare and productivity. Above this temperature, rapid breathing, the problem of not emitting heat from their bodies to the environment, decrease in feed consumption and live weight gain begin to be seen in chickens. At high temperatures, 34-35°C, egg production decreases by approximately 30% and feed intake decreases by 30-50%. As a result, measures such as feed management against heat stress, adding heat stress reducing additives to feed and water, climatic environmental control in shelters, early life conditioning and genetic selection of breeds with increased capacity of coping with heat stress conditions can be taken.