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Improve the efficiency of the system and the results of environmental impacts

Pig production systems are important contributors to air, soil, and water pollution, in relation with intensive rearing and the use of high-energy and high-protein feedstuffs. Most of these systems rely on imported feedstuffs such as soybean meal, which is mainly imported from Brazil and may be associated with deforestation. The nitrogen content of manure, and the nitrous oxide and ammonia emissions during manure storage, treatment and spreading are positively related to nitrogen excretion in feces and urine. Feeding low-protein diets (balanced in essential amino acids through the incorporation of feed-use amino acids (AA)) to growing- finishing pigs results in reduced nitrogen excretion without modifying animal performance.

Our objective was to quantify the potential reduction of environmental impacts of the production of one kilogram live pig according to various scenarios of AA incorporation, considering all the animal categories in a typical farrow-to-finish pig farm.

Feeding practices reducing protein intake in the diet

Least-cost formulation of feeds, with AA incorporation and free protein content, allows reducing the protein content of feeds for all the animal categories. Simultaneously, the soybean meal incorporation was decreased and replaced by cereals and AA. These modifications of formulas result in reduced feeding cost. The impacts of the production of one kilogram of live pig on climate change (CC), acidification (AC) and eutrophication (EU) are reduced with the increasing incorporation of AA.  The maximal reduction (vs. the scenario without using AA) was 12-30% for climatic change, 33-37% for acidification, and 25-28% for eutrophication. The impacts of pig production on cumulated energy demand, terrestrial ecotoxicity, and land use were poorly affected by the investigated scenarios. In slurry systems, the reduction of impacts was mainly associated to feed production whereas in solid manure systems, the improvements were obtained for the housing and manure management compartments.

Our results demonstrate that low-protein diets, formulated with the incorporation of AA such as lysine, threonine, methionine but also with tryptophan and valine, are the most efficient in reducing the impacts on CC, AC, and EU. Associated to multiphase feeding, the incorporation of AA with free protein content allows reaching the maximal reduction of impacts.

We also showed the low sensitivity of these results to the costs of feed ingredients. Therefore, practices aiming at adjusting the nutrient supply to the animal requirements (in a dynamic way) improve the efficiency of the system and the resulting environmental impacts.

Reduce impacts but also feed costs

A feeding strategy relying on least-cost formulation of feeds, with incorporation of AA and free protein content (but covering the essential amino acids requirements), associated to multiphase feeding, should allow for a substantial reduction of environmental impacts. This is particularly true for eutrophication, acidification, and climatic change which are of major concern in regions such as Brittany. This practice is a win-win strategy which allows reduction of various impacts, without increasing other ones, while reducing feeding cost.  

This work has been used in the Inra study conducted in 2013 to estimate the potential of mitigation of greenhouse gases emissions of agriculture in France in 2030 (Which contribution of the French agriculture to the mitigation of greenhouse gases emissions? Potential and Cost of ten technical actions).

References

• Garcia-Launay F., van der Werf H.M.G., Nguyen T.T.H., Le Tutour L. and Dourmad J.Y. 2014. Evaluation of the environmental implications of the use of amino acids in pig production using Life Cycle Assessment. Livestock Science 161: 158-175. (DOI)
• Garcia-Launay F., Dourmad J.Y., Faverdin P., Espagnol S. 2014. Réduire les émissions de gaz à effets de serre des élevages porcins en diminuant les apports protéiques: stratégies et perspectives. Innovations Agronomiques 37: 39-52. (in french) [lien]
• Pellerin S., Bamière L., Angers D., Béline F., Benoît M., Butault J.P., Chenu C., Colnenne-David C., De Cara S., Delame N., Doreau M., Dupraz P., Faverdin P., Garcia-Launay F., Hassouna M., Hénault C., Jeuffroy M.H., Klumpp K., Metay A., Moran D., Recous S., Samson E., Savini I., Pardon L., 2013. Quelle contribution de l’agriculture française à la réduction des émissions de gaz à effet de serre ? Potentiel d'atténuation et coût de dix actions techniques. Synthèse du rapport d'étude, Inra (France), 92 p. (in french) [lien]

Contact

Florence Garcia-Launay (florence.garcia-launay[at]rennes.inra.fr)