Feed-use amino acids, at constant performance, make it possible to reduce the protein content of pig feeds and nitrogen excretion by the animals, according to F.<nbsp;Garcia-Launay of INRA in St Gilles, France.

In a paper in Livestock Science co-authored by researchers at INRA and Ajinomoto Eurolysine, the group explains that they aimed to assess the environmental impact of pig production in a conventional farm by Life Cycle Assessment (LCA) according to several scenarios of amino acid incorporation into feed.

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 versus 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 multi-phase feeding (MP).

In three scenarios, feeds were least-cost formulated:

• without incorporation of supplementary amino acids (NoAA),
• with amino acid incorporation in feed and reduced protein content (LowCP), and
• amino acid incorporation with free protein content (Min€).

In the fourth scenario, (MinCP), feeds were formulated to minimise protein content.

The average protein content of pig feeds decreased from 190g per kg in 1P-NoAA to 123g per kg in MP-MinCP as amino acid supplementation increased.

At the same time, the incorporation of soybean meal into feeds decreased from 197kg per tonne down to 70kg per tonne in MP-MinCP. This reduction of soybean meal incorporation was concomitant with a decrease in feed cost.

The incorporation of 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€ and 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 amino acid incorporation and multi-phase 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 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, concluded Garcia-Launay and co-authors.

Reference

Garcia-Launay F., H.M.G. van der Werf, T.T.H. Nguyen, L. Le Tutour and J.Y. Dourmad. 2014. Evaluation of the environmental implications of the incorporation of feed-use amino acids in pig production using Life Cycle Assessment. Livestock Science. 161:158-175.

April 2014