Raising cheap chicken has a hidden cost

Fast growth affects health, study suggests

Much-hyped chicken sandwiches and $5 rotisserie birds come at a toll beyond their price tags. For fast-growing broilers — chickens raised for meat — cheap food comes at the cost of well-being. As breast yield and growth rate increases, animal welfare worsens, according to a new study by University of Guelph researchers. Slower-growing breeds may fetch a higher price, but could result in improved health and meat quality.

The largest and most comprehensive of its kind, the researchers studied more than 7,500 chickens reared at U of G's Arkell Research Station. Previous studies have compared different genetic strains, but animal welfare scientists Tina Widowski and Stephanie Torrey evaluated an unprecedented 16, which were bred for four growth rates, among other characteristics.

“Getting the opportunity to study strains that have never before been available in North America was really exciting for us,” says Torrey, an adjunct faculty member with the Department of Animal Biosciences. “We made it as comprehensive as we could so that we could really take advantage of having those birds with us.”

Widowski, an animal biosciences professor who holds the Egg Farmers of Canada Chair in Poultry Welfare, adds: “What's really unique about our study is we had a large base of genetics. The genetics companies worked with us very closely and we couldn't have done it without their collaboration.”

To satisfy an appetite for ample breast meat at low cost, fast-growing broilers typically reach market weight (roughly two kilograms) in about 35 days, the researchers explain. Raised for their large breast muscles, they have short legs, which impact mobility. Slower-growing breeds, taking at least a week longer to reach market weight, had improved welfare.

Because of the Code of Practice — “a consensus-based, scientifically informed document that the industry uses with the minimum and recommended standards for chicken producers” — Torrey says, overall welfare is higher in Canada than it is the U.S. While the industry gets better each year, she adds, there are still improvements to be made, especially in the use of fastest-growing genetics.

“The biggest issue is lameness. There was a recent study from the U.S. on commercial farms that put the prevalence of mild to moderate lameness around 15-30 per cent. And severe lameness, where the birds cannot walk at all, around three to five per cent,” says Torrey. “Given how many birds are produced globally, that would mean millions of birds would not be able to walk. And there are also studies to show that severe lameness is painful. So that means that there are essentially millions of birds that are in pain.”

To measure the broilers' activity levels, the researchers outfitted them with a non-invasive Fitbit-like device, which they strapped around their wings like a backpack. They placed a 10-centimetre-high beam in the middle of the pens for a period of five hours, during which time they counted the number of times the chickens crossed the beam as they travelled between their food and water.

“This test has been validated against traditional gait-scoring systems for determining lameness in chickens: The more lame birds are, the fewer times they'll cross,” says Torrey. “What we found was that the number of crossings decreased as growth rates increased. Compared to the slower-growing strains, the conventional strains crossed about four fewer times.”

In addition to identifying differences in mobility and activity levels, the researchers found higher instances of foot lesions and muscle myopathy (defects in the meat) in faster-growing broilers.

Slower-growing genetics are promoted in specialty markets, Widowski says, and there's a trend toward them in Europe. In countries such as Germany, the Netherlands and France, Torrey explains, slow-growing broilers could take between 20 and 50 extra days to reach the same market weight. This additional time has implications for producers — due to the cost of feeding and housing animals for a longer period — and consumers in terms of higher cost.

“We were looking at strains that could potentially be viable in the North American market where consumers value breast yield and price as well,” says Torrey. “We had birds that took a week or two weeks longer to get to the same body weight as the conventional strains that are used. And there were some that took a week longer that did OK in terms of welfare outcomes. But as

THE FASTER THE GROWTH, THE WORSE THE OUTCOMES.

a whole, the growth rate and breast yield related to most of the welfare outcomes that we studied: The faster the growth, the worse the outcomes.”

The researchers also found low overall mortality, and fewer instances of bone deformities and cardiovascular problems than were prevalent among broilers 20-25 years ago. Once these traits were identified, breeding companies made changes to their selection schemes. This was encouraging to see, Widowski and Torrey say, because it illustrates how effective selective breeding can be in improving bird welfare.

“The trick is also maintaining economic viability, and there are environmental implications as well: If you keep a bird longer in a barn, and there's more food that goes into them when they're less efficient, there are other trade-offs involved that consumers and society in general have to take into account,” says Widowski.

The researchers hope their study will inform industry as well as the general public.

Awareness of how meat and poultry is produced, Torrey says, is integral to any systemic change.