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A Systems Approach for Evaluating Productivity, Nutritional Efficiency, and Environmental Impacts of Feeding Programs for Growing-finishing Pigs

Yang, Z., Y. Hung, J. Jang, P. Urriola, L. Johnston and G. Shurson

Traditional evaluation of swine feeding programs have generally focused only on economically important performance and carcass measures but achieving sustainable pork production also requires formulating diets to reduce negative environmental impacts. Therefore, a systems approach is needed to evaluate swine feeding programs from multiple perspectives. The objectives of this study were to compare productivity, nutritional efficiency, and environmental outcomes of four different growing-finishing feeding programs consisting of diets containing corn and soybean meal (CSBM), low protein CSBM supplemented with crystalline amino acids (LP), CSBM with 30% distillers dried grains with solubles (DDGS), and DDGS supplemented with crystalline Ile, Val, and Trp (DDGS+IVT). In experiment 1, growth performance and carcass characteristics of pigs (n=288; initial BW=36.9±4.2 kg) were measured in a 12-wk feeding trial. There were no differences in ADG, ADFI, carcass yield, and carcass fat-free lean percentage observed among feeding programs but gain:feed was greater (P <0.05) in pigs fed CSBM and DDGS+IVT than pigs fed LP. In experiment 2, nitrogen and phosphorus balance of pigs (n=32; initial BW=59.9±5.1 kg) were determined in a metabolism study. Pigs fed CSBM had greater N retained (P <0.05) than those fed other diets, but pigs fed LP had greater (P <0.05) protein efficiency ratio but lower (P <0.05) P intake than pigs fed CSBM and DDGS. In experiment 3, data collected from the previous 2 experiments were used to calculate environmental impacts of the four feeding programs through life-cycle assessments using Opteinics™ (BASF, Lampertheim, Germany).

Feeding CSBM had the least impact per 1,000 kg carcass weight on climate change and fossil resource use, while LP had the least impact on acidification, water use, and total environmental footprint. These results indicate that each feeding program has comparative advantages depending on the metrics, which requires using a holistic systems approach for decision-making to improve the sustainability of pork production.