The transition of the UK laying hen industry from cage-based to free-range systems has been largely motivated by consumer demand for higher welfare standards. These systems allow hens to engage in natural behaviours like dustbathing and foraging, yet they also present new welfare challenges including an increased exposure to parasites in faeces and soil and a higher risk of mortality from cannibalistic feather pecking. Despite widespread recognition of both issues, there remains little research examining a relationship between parasitism and injurious pecking.

The aim of this pilot project is to explore potential associations between parasite burdens, indicators of immune and metabolic stress, and the prevalence of injurious pecking in free-range laying hens. The study will involve collecting hens that have died naturally or been culled for welfare reasons on commercial free-range farms, then conducting postmortem exams examining spleen and liver weight, body condition, and burdens of the intestinal nematodes Ascardia galli and Heterakis gallinarum. In parallel, behavioural observations will be conducted on-farm and soil and litter samples will be collected to test for contamination with A. galli and H. gallinarum eggs.

This research aims to determine if there is a relationship between parasitism, immunological and metabolic stress, and injurious pecking. If an association is found, it may lead to targeted interventions for hens with heightened susceptibility – including better parasite management protocols with outdoor ranges in mind, dietary modifications to increase immune function, or improved environmental enrichment to reduce injurious pecking. As a pilot study, finding these associations will serve as a foundation for larger-scale research which could identify precise causal pathways between these variables. Ultimately, this project aims to advance the understanding of the health and welfare of free-range laying hens and the risk factors for poor welfare in these systems.