Raising slower-growing broiler chickens means less efficiency for producers and potentially higher costs for consumers, but it would improve bird welfare, according to a large and comprehensive study of broiler chicken welfare by researchers at the University of Guelph in Ontario.

The team hopes the study will lead poultry breeders and producers to select traits associated with better welfare, an announcement from the university said.

This is a potentially costly move, but one that may end up benefitting the industry by lending support to higher animal welfare standards and improved meat quality favored by consumers, Guelph animal biosciences professor Tina Widowski said.

“We found that, overall, many indicators of welfare are directly related to rate of growth,” said Widowski, who led a team of experts in poultry welfare, nutrition, physiology and meat science at the University of Guelph.

Developed mostly through selective breeding, fast-growing birds reach market weight of about 2 kg in about 35 days and satisfy consumers’ desire for large, uniform chicken breasts. By changing their body shape, this breeding has yielded large breast muscles but also short legs that make it difficult for chickens to perform normal activities, the researchers said.

Animal welfare concerns have led to development of slower-growing breeds that take at least a week longer to reach market weight, the university said. Raising chickens more slowly adds expense for producers, especially in extra feed costs.

The researchers studied more than 7,500 chickens raised at the University of Guelph’s Arkell Research Station. They looked at 16 genetic strains bred for four growth rates as well as other traits.

Outfitting the birds with wearable devices, they compared mobility and activity. An obstacle test allowed the team to compare leg strength among the different poultry strains. They monitored birds’ use of enrichment items, examined birds for foot lesions and also looked at meat quality, the announcement said.

As expected, faster-growing chickens were less active and mobile and had poorer foot health — all markers of poorer welfare, the researchers said. The fastest-growing birds also had breast muscle damage, which typically results in economic losses because of poor meat quality.

“It was the combination of high breast yield and fast rate of growth that led to poorer welfare outcomes,” said Stephanie Torrey, an adjunct faculty member with the Guelph department of animal biosciences.

The researchers said they were encouraged to find that some major health and welfare issues — including skeletal leg muscle problems and heart failure — that were common about 20 years ago no longer prevail.

“That means breeder selection to resolve those problems has worked, and we hope that results of our study will set the direction for the next phase of genetic changes leading to welfare improvements,” said  Widowski, who holds the Egg Farmers of Canada chair in poultry welfare.

Referring to a new report written by the researchers and provided to the Texas-based Global Animal Partnership (GAP) in July, Torrey said the findings may help retailers attract customers looking for products from animals raised under higher welfare standards.

“This will perhaps arm some companies to differentiate their product based on welfare outcomes,” Torrey said. “Whether or not average consumers will be willing to pay a premium for improved welfare outcomes remains to be seen, and we don’t know how the economic benefits of reduced meat quality defects may offset the increased costs of production.”

Looking for data to support its welfare standards and to determine optimum breeds and management methods, GAP provided the University of Guelph with a research grant in 2018 to study broiler welfare. The study was funded by $1 million from GAP, the University of Guelph's Food from Thought project and the Ontario Ministry of Agriculture, Food & Rural Affairs.

The researchers are now preparing a series of peer-reviewed articles for publication within the next year.