Genotype by Environment Interactions in Livestock Farming

Genotype by environment interaction, often referred to as “GxE,” is the phenomenon for which the breeding value of an individual depends on the environmental conditions and the effect of an environmental factor depends on the individ- ual’s genetic background. A breeding program that accounts for GxE allows, among other things, the development of breeds and lines that are par- ticularly adapted to specific environmental and management conditions. Historically, animal breeders have neglected the phenomenon, and it has seldom been exploited in genetic evaluations. Conversely, plant breeders have made it familiar and developed breeding plans that take advantage of such interaction effects. The reasons for this difference are multiple but can mainly be reconducted to the following two: (1) The devel- opment of new plant germplasm is a process that is more affordable than the development of new animal germplasm. Such cost-effectiveness of plant breeding allows developing lines that will be used under a limited number of conditions. The development and maintenance of animal germ- plasm adapted to only marginal breeding systems will likely be uneconomical. (2) Animal hus- bandry allows managing livestock in a more pre- cise manner than agronomy does with plants. For example, animals’ diets can be controlled with high precision, while rainfall and nutrient avail- ability in the (open-field) soil can only be con- trolled to some extent. Better control of the environmental conditions lower the need to develop germplasm adapted to harsh conditions.