348 Integration of Nutrition with Air and Water Environmental Concerns

Abstract

Abstract The dairy and beef cattle industries face a number of environmental challenges related to air and water quality as well as the use of limited resources such as water and fossil energy. Mitigation strategies are available and being developed to reduce environmental impacts, but economical solutions remain a challenge. Assessment of mitigation strategies requires a comprehensive evaluation to assure that benefits in one component are not offset by harm in another. Process-based modeling and life cycle assessment provide tools for conducting this type of integrated evaluation. The most cost-effective strategies often begin with animal feeding. The diet of the animal affects resource use and nutrient excretion where the amount and form of nitrogen and phosphorus excreted affect air and water emissions. National assessments of the U.S. beef and dairy industries indicate where mitigation is most needed. Although greenhouse gas emissions receive most of the concern today, water consumption is another important concern, particularly for producers in drier regions such as the western United States. Over 90% of the water consumed in beef and dairy production is used in irrigated feed-crop production. Therefore, animal diets that use byproduct or other feeds not related to irrigated production can provide large reductions in the water footprint of beef and dairy products. Another emerging concern is that of ammonia emission where beef and dairy cattle may contribute more than half of the national emission inventory. Efficient protein feeding is the most economical and effective step that can be taken to reduce this environmental impact. Simulation of mitigation strategies using production system models provides comprehensive evaluation and prioritization among available and possible options, giving direction toward more sustainable ruminant animal production systems.