Healthy hen or happy hen? Disease-welfare trade-offs in extensive poultry systems

Change in poultry production systems from highly intensive eg caged laying hens and mass indoor broiler rearing, towards more extensive or free-range systems is accelerating, driven by consumer concerns over animal welfare. Consumers are generally unaware that intensification brought significant benefits for disease control through biosecurity and breaking transmission cycles.
Hypothesis:
-Birds in extensive poultry systems experience higher levels of infection with environmentally transmitted parasites;
-These parasites are associated with poor health and production outcomes;
-Health and other welfare indicators can be combined into a meaningful single currency for optimization across dimensions;
-Modification of extensive systems can achieve improved health without compromising on other welfare, maximizing benefits of extensification.

Work plan
-Sample parasite infections and host status across intensive-extensive gradient
Data will be analysed using generalized linear mixed models, to characterize correlations between housing system and the load and diversity of parasites and pathogens, to address the first hypotheses.
-Develop and apply precision interventions to attenuate infection risk in extensive settings
Population dynamic models will be developed for the major macro and microparasite species found. The models will be used to evaluate the impact of refinements to housing on parasite transmission. Selected interventions will be trialed in participating extensive flocks experiencing disease problems and impact on infection, performance and welfare measured.
-Combine welfare metrics and evaluate consequences of system change and interventions
Individual welfare indicators will be compared across production systems and interviews (of producers, health advisors and the public) on perceptions of welfare and disease impacts used to derive a novel disease welfare indicator.