Incubation and hatching.

AbstractThe emphasis of poultry incubation research since the late 1980s has focused on four different themes, namely: (i) the relationship between incubation temperature and embryo temperature; (ii) how to engineer commercial incubators to meet the requirements of the embryo; (iii) the effect of genetic changes to poultry breeds on their incubation requirements; and (iv) the effect of incubation environment on the post-hatch performance or epigenetic adaptation. It is the intention of this short review to focus on these four areas of research and to discuss how they are affecting commercial practice. A simple systems model is used to describe how embryo growth and metabolism, the properties of the egg in which the embryo develops and the environment of the incubator interact to determine the embryo temperature. The model shows that the relationship between the egg and its incubation environment is a dynamic process, with the embryo responding to its incubation environment but also affecting the environment. Our understanding of these interrelationships has resulted in better design of artificial incubators and the development of methods to directly measure the response of the egg to its environment. The third section of the review discusses whether the genetic improvements to poultry in both egg and meat production have altered the incubation environment of the embryo. It is concluded that there are differences in embryo metabolic rate between genetic lines, which may impact on the optimum incubation environment. It was also noted that the mechanism by which genetic selection had affected embryo metabolism was not yet understood. The last section of the chapter discusses the possibility that post-hatch performance can be affected by the incubation environment and presents evidence to show that this may indeed be the case.