Life cycle assessment of three bull-fattening systems : effect of impact categories on ranking/ created by Hanh Nguyen Thi Tuyet, Hayo van der Werf and Michel Doreau

The aim of the current study was to analyse the environmental impacts of fattening bull systems using life cycle assessment (LCA). Three contrasting bull-fattening systems practised in France were compared. Diets H, MS and C differed by the nature of the forage consumed (hay, maize silage and wheat straw, respectively) and the proportion of concentrate, i.e. ground maize grain and soybean meal (0·51, 0·37 and 0·86, respectively) in the diets. Diet MS resulted in the lowest cumulative energy demand and in the highest acidification potential per kg of body weight gain (BWG). Eutrophication potential per kg of BWG was highest for diet C and the lowest for diet H. The relative contribution of eutrophication and acidification impacts by feeds and manure varied according to diet. The system using a hay-based diet resulted in the highest land occupation per kg of BWG and in the lowest impact per ha of land occupied for all impacts. It was found that the use of LCA, involving a multi-criteria assessment allowing the expression of results according to several functional units (kg of BWG and ha of land occupied) is essential to analyse the effectiveness of a pollution reduction strategy.