Evaluation of the environmental implications of the incorporation of feed-use amino acids in pig. production using Life Cycle Assessment

摘要

Feed-use (FU) amino acids, at constant performance, make it possible to reduce the protein content of pig feeds and nitrogen excretion by the animals. The aim of this study was to assess the environmental impact of pig production in a conventional farm by Life Cycle Assessment (LCA) according to several scenarios of FU amino acid incorporation. Two modalities of waste management (slurry or solid manure), two hypotheses of protein sources (soybean meal only, or soybean meal, rapeseed meal and pea) and two soybean origins (Centre-West Brazil vs. average Brazilian soybean) were considered. In each scenario investigated, gestating, lactating, pre-starter and starter feeds were formulated. Fattening pigs were fed either with only one feed (1P), or with two feeds (2P) or according to multiphase feeding (MP). In three scenarios, feeds were least-cost formulated: without incorporation of FU amino acids (NoAA), with FU amino acid incorporation and reduced protein content (LowCP), and FU amino acid incorporation with free protein content (Min). In the fourth scenario (MinCP), feeds were formulated to minimize protein content. The average protein content of pig feeds decreased, from 190 g/kg in 1P-NoAA down to 123 g/kg in MP-MinCP while FU amino acid incorporation increased. At the same time, the incorporation of soybean meal into feeds decreased from 197 kg/t down to 70 kg/t in MP-MinCP. This reduction of soybean meal incorporation was concomitant with a decrease in feed cost. The incorporation of FU amino acids in low protein diets clearly reduced the impacts of pig production on Climate Change (CC), Acidification (AC) and Eutrophication (EU). The lowest CC, AC and EU potential impacts were reached with the Min or MinCP scenarios, for which tryptophan and valine were incorporated in pig feeds. The impacts on terrestrial ecotoxicity, cumulative energy demand and land occupation were less sensitive to the studied scenarios. The combination of FU amino acid incorporation and multiphase feeding of growing-finishing pigs produced the largest reduction of CC, AC and EU impacts. The underlying mechanisms include the substitution of soybean meal and extruded soybean by cereals and FU amino acids and the reduction of nitrogen excretion which further reduces nitrous oxide and ammonia emissions. This study suggests that environmental impacts of pig production in France can be further reduced through feeding practices, especially for acidification, eutrophication and climate change.