The overall aim of this project is to address Defra’s stated policy need to “assess the impact of commercially relevant feed restriction on the subjective experience of broiler breeders”.
This will be achieved by:
1) Behavioural techniques known as conditioned place preference (CPP) and conditioned place avoidance (CPA), which will be used in combination to quantify how a chicken feels overall about an environment where it is feed restricted in contrast to an environment with a more generous feed allowance but where it must endure negative aspects of housing such as a reduced space allowance, lack of litter or social isolation.
2) Negative subjective states can be quantified by measuring neurochemical changes linked with negative mood. Reduced synthesis of brain derived neurotrophic factor (BDNF) in the hippocampus, reduced hippocampal volume and increased circulation of the cytokine interleukin-6 (IL6) have been shown to occur in animal models (including birds) of negative subjective states (e.g. mood disorders such as anxiety and depression). To further validate these measures specifically in the context of feed restriction, our experiments will include a study of incubating chickens (which show a voluntary reduction in feeding behaviour) with pair-fed non-incubating controls.