Epsilon Archive for Student Projects

Abstract

Chickens raised for meat, termed broilers, convert feed at high rates and are reared in highly efficient systems where meat is produced with comparatively low emissions of greenhouse gases (GHG). However, the intensive nature of these systems and of the hybrids they use are associated with severe animal welfare concerns. Alternative systems introducing several welfare features have been proposed to reduce these issues. However, some welfare features are expected to reduce the efficiency of the system which indicates a goal conflict between minimizing welfare concerns and GHG emissions. To develop a better understanding of this trade-off, this thesis aimed to examine how two prominent welfare interventions, a reduced stocking density in broiler houses and a switch to slower-growing broiler hybrids, affect welfare and the carbon footprint of chicken meat.
With this goal in mind, the current scientific evidence of these interventions’ influence on welfare was identified using a systematized review and their impacts on welfare indicators quantified. Furthermore, the carbon footprint of chicken meat produced in Swedish conventional systems was determined and adjusted to investigate the impact of introducing the welfare features. In both cases, the focus was to determine the relative impacts of the welfare interventions to avoid confounding factors and to allow a comparison of both aspects. Reducing stocking densities was found to moderately increase some welfare indicators but lower improvements were generally found when stocking densities were reduced below the density used in Swedish broiler houses. A switch to slower-growing broilers had a considerable effect on most of the investigated indicators, while the highest improvement was found when the two interventions were combined. Opposite trends were found for GHG emissions as a reduced stocking density of 24 kg/m2 increased the carbon footprint by 2%, a switch to slower-growing broilers by 16-32%, and a combination of both to 18-34%. The largest goal conflict was found for a switch to slower-growing broilers followed by stocking slower-growing broilers at reduced densities, while a slight conflict was found for reducing the stocking densities in conventional broiler houses. Trade-offs of using a slower-growing hybrid was reduced if a moderately-slow growing hybrid was used and if this was combined with a reduction in stocking density.