Breeding to prevent cannibalism in hens

27-04-2010 | | |

As more states move to ban restrictive livestock cages, the campaign to free egg-laying hens from cramped cages and shift them to pens animal rights advocates call more humane could be poised to unintentionally boost deaths among those birds.


Researchers say decades of breeding to make the white leghorn hens that lay most of the nation’s eggs more productive have also boosted the birds’ territorial instincts, making them prone to pecking attacks so fierce they’re often called ‘cannibalism’.

Scientists and egg producers warn that deadly skirmishes that start with feather-plucking and turn into bloody frenzies when a bird’s pecking breaks a flockmate’s skin will increase if those same aggressive hens are moved from small cages with 5-10 birds to open pens that can hold dozens.

Animal rights groups want those pens to replace the small ‘‘battery cages’’ they call cruel because hens are so confined they can’t even spread their wings.

A total of 7 states in the US have passed laws that will eventually ban or limit different types of livestock cages. California and Michigan have passed laws that will eventually ban battery cages for chickens, as has the EU.

As those bans go into effect and more birds move to open pens, a solution may lie in the work of an influential Purdue University scientist whose breeding method produces more congenial, peaceful chickens by focusing on the birds best suited for life in groups. The white leghorns bred by William Muir stand sedately wing to wing, staring back timidly from their cages at a Purdue research farm in northern Indiana.

The easygoing egg-layers Muir has dubbed ‘‘Kinder Gentler Birds’’ don’t need their beaks trimmed and blunted, another industry practice deplored by animal rights groups, but which is intended to prevent pecking deaths.

Breeders working over several decades chose the most productive birds to reproduce, resulting in white leghorns that each year can lay 300-320 of the large bright-white eggs most popular with Americans. Muir said that approach unintentionally produced birds that also have a heightened self-preservation instinct and desire to literally be at the top of the pecking order.

‘‘If you have a lot of birds that want to be top bird there’s going to be fighting,’’ Muir said. ‘‘If you leave their beaks intact it’s a bloodbath. They will literally kill each other. It’s kind of a dominance thing. … They just peck each other to death.’’

Reportedly, about 5% of hens on factory farms die each year from injury and disease. To reduce fights, they are kept in dim lighting in cages where each bird has an average 67 square inches of space, or two-thirds of a sheet of notebook paper, reports continue.

The Humane Society of the United States maintains such conditions cause hens needless suffering and increase their agitation by limiting their ability to walk around and preventing them from acting on natural urges to peck, nest and perch. ‘‘It really is difficult to imagine a more restricted, miserable existence,’’ said HSUS senior director Paul Shapiro.

Costs will rise

Gene Gregory, president of United Egg Producers, a trade group that represents farms that produce about 90% of the nation’s eggs, said there would be more pecking deaths in open cages and egg prices would go up because more workers would be needed to manage the birds.

Shapiro agrees that costs would rise, but disputes the claim that moving hens from battery cages to open pens would cause more deaths. He said proper management can result in no difference in death rates and adds that pens could reduce attacks by allowing hens to perform natural behaviors such as pecking the ground.

Shapiro acknowledges that breeding gentler chickens would be a plus if it could eliminate the practice of break trimming.

Ian Duncan, a professor emeritus of animal welfare at University of Guelph in Guelph, Ontario, also has advocated for an end to keeping hens in bare battery cages, but he said commercial white leghorns would have a higher rate of cannibalism in pens.

Cannibalism is a learned behavior, passed from one territorial hen to another, Duncan said, and while he views battery cages as a grim existence, the fact is those cages limit contact between birds and make pecking easier to manage.

‘‘It seems counterintuitive — you would think that it might be worse in a battery cage — but it’s not, it’s worse if you keep birds in big groups,’’ Duncan said.

He said Muir’s work holds the promise of making commercial hens better suited for a more spacious lifestyle and less prone to clashes.

Muir said it’s hard to compare his and his colleagues’ birds with the more aggressive ones that have become the poultry industry standard, but he believes their hens would live longer and lay more eggs because they waste less energy fighting.

Hendrix Genetics, a Dutch company that breeds the layers that produce about half the world’s eggs, has begun using Muir’s technique, breeding birds chosen for their personality as well as their ability to lay eggs.

The company had already been working on a breeding technique aimed at producing ‘‘more robust’’ animals with lower death rates, said Gerard Albers, director of Hendrix Genetics’ BV Research and Technology Centre. But he said Muir’s ideas gave it a boost as the EU moves closer to its 2012 deadline for abolishing battery cages.

The company’s work is moving faster now, he said, and the first of its gentler birds will be available in 3 years.

Source: Farm Forum


Natalie Kinsley Freelance journalist