Providing cross-species comparisons of animal welfare with a scientific basis

Animal welfare issues may involve different species and require decision-makers to compare welfare across species. Up to now applied ethologists have largely ignored questions involving cross-species comparisons. This paper discusses the question whether cross-species comparisons about animal welfare can be provided with a scientific basis, i.e., based on scientific arguments. The arguments pro and contra are reviewed. Conceptually, cross-species comparisons should be possible, but at the explanatory and operational levels substantial problems remain to be resolved. An example is given comparing the welfare of laying hens in battery cages, conventionally housed fattening pigs, conventionally housed broilers and dairy cattle at pasture. Possibly a method could be developed that makes welfare assessments across species more transparent and coherent, and that is based on available scientific information. An outline of such a method is described in this paper.