Genotype-environment interactions in rabbit and pig breeding for new production systems

This literature review explores genotype×environment (G×E) interactions in rabbit and pig production. This occurs if the difference between genotypes depends on the environment, leading to re-ranking or scale effect between genotypes. High temperatures and seasonal variations strongly influence reproductive, growth and feed efficiency performance, with moderate genetic correlations between environments. Animal lines show different sensitivities to heat stress, underlining the importance of selecting animals under conditions that reflect their future rearing environment. Rabbit behaviour and performance differ according to the type of housing, such as cages, pens or access to a grazing area. While G×E interactions are limited for growth traits, they are more pronounced for behaviours, particularly in enriched systems. In swine production, organic systems or more restrictive production environments reveal significant G×E interactions for growth and feed efficiency. High-fibre diets or diets including co-products also lead to differences in feed efficiency and body composition, with re-ranking between genotypes. These results show that G×E interactions influence a variety of traits depending on rearing conditions, and require adaptation of selection strategies. Future production systems, subject to increased climatic constraints and more extensive practices, must integrate these interactions. Genetic selection will have to be based on evaluations in representative environments to ensure that the animals are adapted to the challenges of climate change and new societal expectations.