Thermal acclimation during embryogenesis; effect on pre and post hatch performance of commercial broiler chickens; a review

Abstract

This work reviews the effect of thermal acclimation (TA) during embryogenesis on the pre and post hatch performance of broiler chickens. Genetic selection and improvements for faster growth and breast muscle production has rendered commercial broiler chickens more susceptible to heat stress. Chickens do not have sweat glands thereby resulting to other methods of stress adaptation such as conduction, convection, radiation, panting, and reduction of feed intake during high temperature periods. This leads to several physiological changes which negatively affect production and welfare performance especially in tropic and humid regions. Epigenetic thermal acclimation during embryogenesis is a strategy that could enhance embryonic development and the adaptive responses of broiler chickens to post hatch environmental stimuli. Epigenetic thermal acclimation involves the exposure of embryos to a certain higher temperature for certain duration of time from embryonic age (EA) 10 or 11 during which the hypothalamus-pituitary-adrenal (HPA) and hypothalamus-pituitary-thyroid (HPT) axis are developed enough to withstand thermal exposure. The available literature revealed that the exposure of embryos to thermal challenge could improve embryonic development, hatchability, and post hatch growth as well as the adaptive response of broiler chickens to post hatch environmental stimuli however, exposure to extreme higher temperature or for a longer duration could negatively affect development. It is therefore concluded that exposure of embryos to a certain higher temperature within a certain embryonic period for a certain duration could be a potential strategy to improve the pre and post hatch performance of broiler chickens.