The Problem with Fast-Growing Broiler Chickens

Humane treatment of livestock is about better breeding, not just living conditions.

chickens in a barn
Chickens in a barn.

Getty Images / Stringer

The life of a modern broiler chicken is notoriously bad. It seems that every few months a new exposé comes out, revealing cramped conditions, dirty bedding, and pecked bodies. A common response is to give the birds slightly better places to live, with larger cages, a bit more ventilation, and a doorway through which to access the Great Outdoors, even if it's just a patch of dirt where only a fraction of the chickens in the building can fit.

But – surprise, surprise! – it turns out, these measures still don't make the chickens' lives any better because there's an anatomical problem at play. Researchers from the University of Guelph, in conjunction with the Global Animal Partnership, have just wrapped up a two-year study of broiler chickens and concluded that most are in chronic pain as a result of their rapid growth. And that pain is not something that can be addressed by design changes to the barns they live in; it's a much bigger problem that challenges the whole industrialized chicken-raising model and the actual breeds we're choosing to raise and consume.

As Kelsey Piper reported for Vox

"For decades, we’ve been breeding chickens to be maximally economically efficient, which mostly means that we raise them quickly, and to be much, much meatier. And it turns out this causes agonizing chronic pain, joint and movement problems, and other issues — even if you try to give the birds good living conditions."

The University of Guelph researchers looked at more than 7,500 chickens from 16 different strains, studying differences in behavior, mobility, anatomy, mortality, feed efficiency, and meat quality as they relate to the bird's growth rate. What they found was that faster-growing chickens have more health problems than slower-growing ones, such as lesions on their bottoms of their feet, hock burns on their rears that make it painful to stand and sit, and heart and lung problems. They concluded that these birds experience pain on a regular basis.

The fast-growing chickens are less inclined to move around, remaining sedentary for longer because movement is painful. This was measured using behavioral tests, such as removing food and water sources from the pen for one hour, then returning it with the addition of an obstacle (a beam) that the chickens would have to cross in order to access the food and water. This obstacle test revealed that fast-growing birds crossed less frequently than slow-growing birds.

Another test involved seeing how long a bird would stand before choosing to sit down in water – something that chickens hate. The test period was a maximum of ten minutes, and the heavier, faster-growing birds were much quicker to give in. From the study: "This may indicate differences in muscle fatigue related to growth that limits faster growing strains in supporting their body weight."

This research shows that the idea of humane conditions has to go beyond the facilities that chickens inhabit. It needs to take into consideration the actual breeds of bird that we're choosing to raise, and perhaps lead to opting for smaller, slower-growing chickens that do not provide as much breast meat but are subjected to (slightly) less of a miserable existence for their short lives. 

In terms of overall meat yield, there's not a significant difference between fast- and slow-growing birds, but the distribution is different: "Breast yields increased with increasing growth rates; thigh, drumstick and wing yields decreased with increasing growth rates." So if people were willing to trade chicken breasts for more thighs and drumsticks, it could create more demand for slower-growing and somewhat happier birds.

It's a tricky issue. Some readers may argue that quitting eating animals altogether is the best way to go (and it very well might be); but for all the people who won't stop eating chicken, is it not better to pursue certain improvements that alleviate animals' suffering than to ignore them altogether? I would argue yes.

Read the full study here.