Epigenetics, genes and the environment: what importance for breeding practices and selection methods in poultry ?

Epigenetics is commonly defined as the set of molecular mechanisms involved in gene expression regulation that are reversible and transmissible during development, and sometimes between generations, without altering the DNA sequence. Several epigenetic marks involved in chromatin regulation are now well known, such as the methylation of DNA cytosines, histone post -translational modifications, and non -coding RNA. Thanks to the technological development of high -throughput DNA sequencing, epigenetic marks can now be investigated at the whole-genome scale. It is also well known that the epigenome (the whole set of epigenetic marks in a tissue) is sensitive to environmental fluctuations, including temperature or nutrition, and can be considered as a mediator between the genes and the environment. Phenotypic programming strategies based on epigenetic mechanisms could thus be used as a lever to adjust the phenotype of individuals with their living conditions. Moreover, over the last decades, genetic selection has contributed to a considerable improvement in animal performances. Although the genetic component can be estimated with some accuracy, a large part of the phenotypic variability, considered to be of environmental origin, is not directly accessible by genetic approaches. In a context of diversification of production environments (climate change, production methods that are more respectful of welfare and the environment...), it is necessary to understand the impact of the environment on phenotypic variation via epigenetic marks, to optimize breeding systems and to predict the phenotype of an animal. Like genomic selection a few years ago, the contribution of epigenetic research could contribute to more efficient and sustainable production systems in poultry farming.