Today’s chickens are not your grandpa’s chickens

MultiChickensAccording to a recent study, chickens today are four times larger than they were 60 years ago but contrary to popular belief, it’s not steroids, hormones or artificial enlargers that are not to blame. Instead, it’s our eating habits that have resulted in the breeding of larger birds.

Published in the Journal Poultry Science and summarized in a recent article, this study compared three types of chickens. One that hasn’t been changed by breeding since 1957, a second that has been the same since 1978, and a third, modern commercial chicken, called the Ross 308 Broiler, which has been bred for selective traits over the past few decades.

The study states that these chickens were fed identical diets for 56 days and resulted in the 1957 breed weighing an average of 905 grams, the 1978 breed averaged 1,808 grams and the 2005 breed tipped the scales at a whopping 4,202 grams — about double the size of the 1978 breed.

“We had never actually tested our 1978 line before, but where they fell were very consistent with what we believed would be the case based on historical selection for growth rate and efficiency,” said Martin Zuidhof, an associate professor at the University of Alberta and one of the authors on the study.

These results reflect the fact that researchers have long stopped selectively breeding the 1957 and 1978 birds for size unlike the modern chickens who are breed not just based on size but for different traits including stronger legs, as well.

To go along with this, selective breeding has also decreased the average age at which these chickens go to market. In 2011 the average age was 47 days; while in 1955 in was 70 days. According to the article, the average market weight for these chickens has almost doubled from 3.07 pounds to 5.80 pounds, with breast size showing an increase of 80%.

These statistics go hand in hand with the increased demand for white meat chicken. According to the National Chicken Council, “the average American consumed about 34 pounds of chicken per year in 1965. Today, the average person eats more than 83 pounds of chicken — significantly more than both beef and pork.”

Zuidhof said he believes this fact also plays into breeders continually aiming for larger chickens that can offer more meat.

“The success of the selection parameters is much higher in poultry than it is in other livestock. That’s why we’re not seeing the same kind of gains in cattle and pigs,” Zuidhof said.  “I personally don’t see a lot of change in the trajectory. People are concerned about animals, and that’s great, but people also want the cheapest food when they go to the supermarket.”

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(Photo: Zuidhof, MJ, et al. 2014 Poultry Science)

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