BROILER GROWTH RATES have a more significant influence on welfare outcomes than stocking density, new research has suggested.

The work compared four different flocks of broilers, two slow-growing breeds stocked up to 30kg/sq m and one slow and one conventional breed of broiler stocked to a maximum of 34kg/sq m.

See also: The cost and returns of slower-growing broilers

The team reared birds on a single farm through four growing cycles.

A range of welfare outcomes – both negative and positive – was assessed by the team.

Over the four groups, the conventional broiler stocked at 34kg/sq m experienced the highest mortality and post-mortem inspection rejections, poorest walking ability, most hock burn and pododermatitis. Litter quality was also worse on this farm, according to the paper.

Positive welfare

Researchers also said fewer birds in this group displayed behaviour indicative of positive welfare, such as enrichment bale usage and qualitative activity scores.

“There are suggested welfare benefits of a slightly lower planned maximum stocking density for Breed B [slow growing birds stocked at 30kg/sq m] and further health benefits of the slowest-growing breed, although these interventions do not offer the same magnitude of welfare improvement as moving away from fast-growing broilers,” the study, which was published in Scientific Reports, says.

The paper was a collaboration between UK-based research business FAI Farms, Bristol Veterinary School and The Norwegian University of Life Sciences.

Commercial trial

Siobhan Mullan, Senior Research Fellow in Animal Welfare at the Bristol Vet School, said: “This first independent commercial-scale trial provides robust evidence of the health and welfare benefits of slower-growing breeds of chicken.

“We hope that it will help to drive changes in supply chains and large companies to bring about real improvements to chicken welfare.”

Broiler motivation

Annie Rayner, FAI’s lead researcher, added: “Broilers are motivated to perform a range of positive behaviours.

“These positive behaviours create positive experiences, resulting in enjoyment or pleasure.

“Displaying positive behaviours improves an animal’s quality of life.

Positive behaviours

“Our seminal study found slow-growing birds to have better health and perform more positive behaviours than conventional fast-growing broilers.

“A shift away from fast-growing breeds would provide the most significant improvement for the lives of the 142 million chickens produced in Europe every week”.

The full paper can be viewed here.