Environmental aspects of ethical animal production.

Livestock and poultry producers face a number of challenges including pressure from the public to be good environmental stewards and adopt welfare-friendly practices. In response, producers often implement practices beyond those required for regulatory compliance to meet consumer demands. However, environmental stewardship and animal welfare may have conflicting objectives. Examples include pasture-based dairy and beef cattle production where high-fiber diets increase methane emissions compared with grain feeding practices in confinement. Grazing systems can contribute to nitrate contamination of surface and groundwater in some areas of the world where grazing is the predominant land use. Similarly, hoop housing for sows, an alternative to indoor gestation crates, can increase the risk of nutrient leaching into soil and groundwater. Direct air emissions may also increase with unconfined animal production as a result of less opportunity to trap and treat emissions, as well as the result of increased cage space and greater surface area per mass of excreta. Coupling welfare-friendly and organic production practices may require greater nutrient inputs to reach the same production end point, resulting in less efficient nutrient use and greater losses to the environment. Dual systems might additionally increase environmental contamination by pathogens. When swine are housed in welfare-friendly huts, Salmonella may cycle more freely between swine and their environment; however, population numbers of pathogenic bacteria may not be different between the indoor and outdoor systems evaluated. Alternatively, these dual purpose systems may reduce antibiotic and hormonal releases to the environment. Finally, intensity of resource use may be different under welfare-friendly and organic practices. In most situations, welfare-friendly production will require more land area per animal or per unit of product. Energy inputs into such systems, from feed production to rearing to product distribution, may also differ from prevalent industrial production practices. Clearly, consumers and producers considering the benefits and costs of ethical animal production practices need to understand the system-wide environmental impacts of these approaches to meeting demand for animal products.