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Notes on Progress: Selective breeding and chicken welfare
We've bred larger and larger chickens. Now can we breed happier ones?
Notes on Progress is a new diary-style format from Works in Progress. In this issue, Ellen Pasternack writes about selective breeding and the wellbeing of chickens. If you enjoy it, please share it on social media or by forwarding it to anyone you think might find it interesting.
Because my father’s allergies prevented us from having more traditional pets, my family was an early adopter of the trend for backyard chickens that took hold among middle class Londoners in the 2000s. Many happy childhood hours were spent feeding kitchen scraps to, collecting eggs from, and playing with our hens – which largely consisted of their good-naturedly tolerating “going for rides” with us on the garden swings and slide. I’d cry when they met their ends at the hands of the local foxes, which was unfortunately not an uncommon occurrence – we cycled through around a dozen chickens over the years in which we kept them.
I find chickens to be sweet, funny, characterful creatures. I also, with some guilt and inner conflict, find them to be delicious. After years of flirtation with “flexitarianism”, and even a brief stint of being almost fully vegan, I find that nothing really feels as good to eat as meat and dairy. But while I’m just about okay with the idea of animals being slaughtered for food, I do also think it’s important for them to have a decent standard of living. I take a keen interest in the welfare of chickens in particular: as a child, I started following the activities of the British Hen Welfare Trust, and it’s long been my ambition, once I have a garden of my own, to adopt a couple of their “ex-batts” – retired battery hens saved from slaughter.
When people think of low-welfare farmed chickens, likely they will think of overcrowded, unsanitary barns, maybe with chickens crammed into cages. But it’s not just their environment that’s the problem – it can also be the chickens themselves.
The average meat chicken sold today is around twice as large as the ones in the 1950s, and capable of an almost explosive rate of growth: from hatching to slaughter in around six weeks. One eye-boggling paper reports what happened when the same diet was fed to groups of chicks from breeds developed in 1957, 1978, and 2005. The 1978 breed was substantially chunkier than the comparatively skinny 1957 birds, but the 2005 birds were something else entirely – at 56 days old, while the other two breeds were still looking essentially like baby chickens, they had on average reached a staggering 4.2 kilos.
Egg production has increased, too: hens bred for laying will now produce around 300 eggs per year, compared to 200 per year in the 1960s.
This is testament to the sheer power of selective breeding, especially when carried out on such a large scale, and on a species with short generation times – with chickens you could have many more iterations of selection in the same time frame than with, say, elephants. Today we have access to a huge amount of genetic and biometric data on individual animals and their descendants, giving an almost god-like ability to manipulate other species. I’ve sometimes wondered whether we should consider this highly deliberate, high-information modern form of selective breeding as “super-domestication”, as it seems quite a distinct process from the way wolves were gradually tamed to become our companions 15,000 years ago.
But while this has helped us make enormous gains in efficiency, feeding many more people on less resources, it can be seriously problematic for the animals themselves.
We can think of organisms as having a constellation of traits, connected to each other in a dense, tangled network. In nature, if a species is selected for larger size, say, that will mean tugging at one thread that then pulls a whole load of other traits along with it. Selection for larger size might also mean selection for sturdier bones, for instance; a more powerful heart and lungs; and often, slower growth. Large size is not much use to you if you don’t have the backing of these supportive features, so we might see body size increase bit by bit, alongside lots of other related traits.
When you apply a massive artificial selection pressure, traits can get pulled way out of kilter with the rest of an organism’s characteristics. Think of pugs, which famously suffer from breathing difficulties in part because they have been intensively bred for a cute little squashed up snout (cute to some – personally I think they look mildly repellent but that’s beside the point).
Intensively bred chickens are similar. They’ve been bred to lay more eggs, grow massively larger, and to reach full size within less time. Problems have arisen because other traits haven’t kept pace: leg defects that leave them unable to walk, and hearts that give out in part because they aren’t strong enough to support such an unexpectedly hefty frame. High egg output leaves birds susceptible to bone fractures because producing all those shells drains their calcium reserves; there is no wild bird that produces an egg almost daily all year round, and breeding chickens to do this is demanding for their poor bodies.
The good news, though, is that selective breeding can be the source of solutions as well as problems. Since around 1990, there has been deliberate selection against leg and foot problems in meat chickens, with the result that the incidence of several types of defect has been reduced to near zero.
Another example: male chickens develop “spurs” on the backs of their feet – sharp bony protrusions with a sheath made of keratin, similar to a cow’s horns. They use these when fighting, and can cause serious injury to other birds – or potentially to the farm workers who handle them. For this reason, the spur buds of male chicks are sometimes removed, which is very likely both painful and stressful for them but is thought to reduce the potential for injuries later on. The UK government’s welfare guidance specifically recommends that breeders select for short, blunt spurs, which reduces the need for this procedure: this is an area where selective breeding can be used relatively straightforwardly for the specific purpose of welfare.
How much further could we take this? If it’s not feasible to farm animals at scale in a super stimulating and rich environment, then would it benefit their welfare if we could reduce their capacity for boredom and frustration? What if we ended up making chickens more and more docile and content, until eventually we had creatures that were basically vegetables that taste like chicken – or perhaps maintained in a state of blissful happiness, like The Matrix for chickens? This feels seriously dystopian, but it’s hard to argue that retaining the capacity for boredom would be better, especially when under-stimulation can cause harmful repetitive behaviours like feather pecking.
One alternative is for every chicken to be raised free-range, with acres of outdoor space and lots of environmental enrichment. But, while there is definitely large scope for improvement in this area, it’s probably impossible for these standards to be adopted at scale without massively multiplying both the global land footprint of chicken farming and the cost of chicken and eggs. It’s all very well saying, as many people do, that animal products should be a rare luxury, but it’s not going to happen if it’s not in the interests of either the suppliers or indeed the billions of people worldwide who currently benefit from having chicken and eggs as an affordable part of their diet.
Along the same lines, we could all stop eating chicken and eggs, and I suppose phase out the 25 billion or so chickens currently on farms – just let them reach the end of their natural lives without reproducing. I don’t think this is going to happen any time remotely soon, though: animal farming is going to be with us for a long time, and while it is, we have a duty to think pragmatically about steps we can take to improve things for those animals. And that means that if we’re going to selectively breed animals for our own convenience, we ought to apply the same principles where we can to give them better lives.
Ellen Pasternack is zoologist and writer. She tweets at @pastasnack_e.
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