Chickens Have Quadrupled in Size in the Last 50 Years

A recent study details how within the last five decades, popular chicken breeds have quadrupled in size, even when fed the exact same diet as their predecessors. Experts explain how this demonstrates the incredible influence - and consequences - of a demand-driven breeding system.

The study, recently published in the aptly named journal Poultry Science, shows how the most popular poultry farm breed from 1957 is more than four times smaller than 2005's commercial breed, the "Ross 308 broiler."

And it would certainly take a long time to broil. The 2005 breed weighs an average of nine-and-a-half pounds. That's more than twice as heavy as the commercial breed popularly used in 1978.

It's important to note that for the study, all three of the aforementioned breeds were fed the exact same diet and raised the same way, allowing researchers to compare the benefits and problems with each breed without the influence of modified feed or antibiotics use - strategies adapted by many modern commercial farmers to capitalize on meat-per-chicken yield.

But even without questionable modern influences, it was still found that the Ross 308 broiler is far more efficient at turning feed volume into breast meat. This was what the researchers called a "breast conversion rate" and it was found to be roughly three times as efficient in the 2005 breed, compared to the 1950s breed. (Scroll to read on...)

Interestingly, it wasn't as if the 2005 bird was simply fatter. The researchers found, in fact, that abdominal fat storage actually decreased thanks to genetic selection pressures over the 48-year period that the three models were popularly used.

However, unintentional consequences were also seen with the "improvements" of the 2005 breed. Bone, heart, and immune system problems were all seen in the modern animals, where that valuable "breast conversion rate" took precedence over even healthy physiology in breeding selection.

The result? The researchers found that the price of poultry has risen at about half the rate of other consumer goods from 1960 to 2004, simply because the availability of the meat has been able to consistently outpace demand.

In this way, the chicken has become an animal that largely exists to serve human needs, even without unnatural food and rearing influences. They are yet another example of how the age of humanity has rewritten the rule book of how species flourish and adapt.