Residual feed intake and breeding approaches for enteric methane mitigation

The expanding world human population will require greater food production within the constraints of increasing societal pressure to minimize the resulting impact on the environment. Breeding goals in the past have achieved substantial gains in environmental load per unit product produced, despite no explicit inclusion of environmental load (and in most instances, even feed efficiency) in these goals. Heritability of feed intake-related traits in cattle is moderate to high, implying that relatively high accuracy of selection can be achieved with relatively low information content per animal; however, the genetic variation in feed intake independent of animal performance is expectedly less than other performance traits. Nonetheless, exploitable genetic variation does exist and, if properly utilized, could augment further gains in feed efficiency. Genetic parameters for enteric methane (CH4) emissions in cattle are rare. No estimate of the genetic variation in enteric CH4 emissions independent of animal performance exists; it is the parameters for this trait that depict the scope for genetic improvement. The approach to the inclusion of feed intake or CH4 emissions in cattle breeding goals is not clear, nor is the cost benefit of such an endeavour, especially given the cost of procuring the necessary phenotypic data