A systems approach to evaluate nitrogen utilization efficiency and environmental impacts of swine growing-finishing feeding programs in U.S. pork production systems.

Developing and evaluating feeding programs that optimize growth performance and carcass composition, while minimizing cost, nutrient excretion in manure, and environmental impact is essential for achieving sustainable pork production systems. Four growing-finishing feeding programs consisting of typical corn-soybean meal (CSBM) diets, low protein CSBM diets containing supplemental crystalline amino acids (LP), CSBM diets containing 30% corn dried distillers grains with solubles (DDGS), and DDGS diets containing supplemental crystalline Ile, Val, and Trp were evaluated to compare their effects on growth performance, carcass composition, nitrogen and phosphorus utilization efficiency, and several environmental impact measures. Pigs fed CSBM diets had greater final body weight than those fed the LP and DDGS diets, and greater gain efficiency than pigs fed the LP diets, but there were no differences in the percentage of carcass lean among feeding programs. However, pigs fed the LP diets had the greatest nitrogen utilization efficiency and the least impact on acidification, terrestrial eutrophication, and water use among these feeding programs. The CSBM feeding program had the least impact on climate change, marine and freshwater eutrophication, and fossil resource use, while the DDGS feeding programs had the least impact on land use.