Slow-growing chickens more mobile

New research study suggests that the reduced mobility found in fast-growing broilers may be an animal welfare issue

Fast growth chickens, despite their name, aren’t particularly fast.

They are inactive and spend a great deal of time sitting, says a University of Guelph report.

In comparison, slow-growth chickens are more active and may have better animal welfare.

Stephanie Torrey and Tina Widowski from the U of Guelph animal bioscience department studied the behaviour and health of more than 7,500 chickens in a project comparing slow-growth to fast-growth broilers.

Over two years, they studied 16 different types of chickens “to understand differences in behaviour, mobility, anatomy, physiology, mortality, feed efficiency and carcass and meat quality,” says a report on the research.

The report was prepared for the Global Animal Partnership, an American organization that labels meat as “animal welfare certified.”

The Guelph researchers grouped chickens into different categories, based on how many grams of weight were gained per day. Conventional breeds in the study gained about 65 grams per day. Slow growth chickens gained 45 to 55 grams per day.

The chickens were kept in identical pens, with about 44 birds per pen.

To assess welfare, the scientists monitored how much time the birds spent walking and some birds wore devices, like a FitBit, to track their movements. They also had the chickens hop over an obstacle, a wooden beam, to get to food and water.

They found that fast growth chickens spent more time sitting than slow growth broilers. And the slow growth birds crossed the beam more frequently to access food and drink.

“For the most part, we found that growth rates influenced our measures of mobility and behaviour. The faster the growth, the worse mobility,” Torrey said in an email.

If a bird spends more time sitting, rather than walking or standing, it can be an important welfare indicator, the report said.

“At 26 days of age, conventional strains spent 73.6 percent of their time sitting, 4.2 percent of their time standing and 2.3 percent of their time walking,” the report noted. “At the same age, all other strains spent an average of 63 percent of their time sitting, 7.8 percent of their time standing, and 4.3 percent of their time walking.”

Lisa Bishop of the Chicken Farmers of Canada said it’s difficult to comment on the Guelph research because it hasn’t been published in a peer-reviewed journal. The scientists have only published a summary for Global Animal Partnership.

“We haven’t seen the full research,” said Bishop, director of brand and communications for the Chicken Farmers. “We don’t have all the data to draw… any major conclusions.”

The Guelph scientists plan to publish several papers in academic journals about their research.

Still, chicken producers cannot switch to slow-growth birds based on one study because there are massive environmental and efficiency benefits from conventional chickens, Bishop said.

Over the last four decades, thanks to better genetics, the industry has lowered its carbon footprint by 40 percent and water consumption by 45 percent.

If a third of Canadian producers switched to slow growth chickens, it would increase annual production costs by $391 million, Bishop said.

It would also require 212 million kilograms of additional feed and create 393 million kg of additional manure.

Research in the United States suggests a complete switch to slow growth birds would increase the cost of production by 25 percent.

“Our models in Canada are suggesting a wholesale switch could increase production costs as much as 49 percent,” Bishop said.

The U of G scientists acknowledged that modern chickens are healthier and have lower mortality, thanks to selective breeding, because chickens now have stronger legs and hearts than they did 20 years ago.

“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.

Torrey made a similar comment in an email to The Western Producer.

It may be feasible to improve the genetics of fast growth chickens so they are more active and have better lives.

“I do think it’s possible to have fast growth and good welfare,” Torrey said. “Slow growth in and of itself is not essential for bird welfare since some factors that decrease growth (disease, poor diet) are unequivocally bad for welfare.”

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