Embryo acclimation : an innovative technique to limit mortality during thermal stress in chicken

Abstract

The selection of fast-growing chickens has favored muscle mass without similar improvement of the cardiovascular and respiratory systems involved in thermoregulation. Indeed, broiler chickens have limited capacities to sustain high temperatures, with reduced performances during moderate and chronic heat exposure, and depressed welfare, morbidity and mortality during acute heat exposure. During the last decade, a great effort concerned early thermal acclimation. This strategy requires a fine tuning of incubation conditions (temperature, phasis of embryogenesis, duration of exposure) favoring long term thermotolerance. Consequences on growth performance and meat quality were also evaluated. Perinatal heat acclimation is aimed at inducing epigenetic thermoregulatory mechanisms that modulate body temperature on a long term. If it is further proved to be efficient on a large scale, early thermal acclimation could favor poultry sturdiness towards temperature variations without affecting growth performance. In this paper, we will review the main techniques of early thermal exposure and the physiological bases of their use. We will focus on the research axes concerning the comprehension of underlying mechanisms and the interest of this technique for poultry species.