There is increasing societal concern surrounding the environmental externalities generated from ruminant production systems. Traditional responses to address these externalities have often been system-based. While these approaches have had promising results, they have served to view the animal as a problem that needs solving, rather than as a potential solution. This review attempts to answer the question: can we breed animals that are more environmentally friendly to address environmental outcomes and satisfy consumer demand? This was done by exploring the literature of examples where animals have been specifically bred to reduce their environmental impact. The use of milk urea nitrogen breeding values has been demonstrated as a tool allowing for selective breeding of dairy cows to reduce nitrogen losses. Low milk urea nitrogen breeding values have been documented to result in reduced urinary nitrogen concentrations per urination event, which ultimately reduces the level of nitrogen that will be lost from the system. The ability to breed for low methane emissions has also shown positive results, with several studies demonstrating the heritability and subsequent reductions in methane emissions via selective breeding programs. Several avenues also exist where animals can be selectively bred to increase the nutrient density of their final product, and thus help to address the growing demand for nutrient-dense food for a growing human population. Animal-based solutions are permanent, cumulative, and often more cost-effective than system-based approaches. With continuing research and interest in breeding for more positive environmental outcomes, the animal can now start to be viewed as a potential solution to many of the issues faced by ruminant production systems, rather than simply being seen as a problem.
Genetic parameters of blood urea nitrogen and milk urea nitrogen concentration in dairy cattle managed in pasture-based production systems of New Zealand and Australia
