Ecological and economic evaluation of Dutch egg production systems

摘要

The upcoming ban on battery cages in the European Union is expected to cause a shift in husbandry systems from predominantly battery cages to enriched cages and loose housing systems, such as barn, free range and organic systems. To gain insight into ecological and economic consequences of such a ban, we quantified the ecological and economic performance of the most commonly used egg production systems in the Netherlands, and identified which parameters explain differences in performance. We included the conventional battery cage system and the following loose housing systems: single and multi-tiered barn systems, single and multi-tiered free range systems, and single and multi-tiered organic systems. Ecological indicators used were deduced from a life cycle assessment, and were: global warming potential, energy use, land occupation, fossil phosphorus use, acidification potential, nitrogen and phosphorus deficit, and nitrogen and phosphorus surplus, each expressed per kg of egg. Economic indicator used was net farm income per full time employee. Based on our ecological evaluation of Dutch egg production systems, we predict that a ban on battery cages in the European Union will increase global warming potential, land occupation and acidification potential per kg of egg produced, whereas the effect on energy use, fossil phosphorus use, nitrogen and phosphorus deficit, and nitrogen and phosphorus surplus depends on relative importance of different loose housing systems. Of all loose housing systems, organic systems had lowest global warming potential, energy use, fossil phosphorus use, and nitrogen and phosphorus surplus, whereas land occupation and nitrogen and phosphorus deficit was lowest for barn systems. Acidification potential was lowest for a multi-tiered barn system. Differences in LCA results among production systems can be explained mainly by differences; in feed conversion, in parameters that determine ecological impact per kg feed ingredient (e.g., crop yield per ha; number field operations, type and amount of fertilization), in drying of grain, in transport of concentrates and manure, in type of hen house and in N excretion per hen per year. Free range systems had highest net farm income, followed by organic systems. Multi-tiered systems had a higher net farm income than single-tiered systems. In case differences among egg and cost prices of different systems do not change after a ban on the battery cage, multitiered free range and organic systems are economically most favourable