Once a chicken with desirable traits has been bred or genetically engineered, tens of thousands of eggs, which will hatch into identical copies, could roll off the production lines every hour. Billions of clones could be produced each year to supply chicken farms with birds that all grow at the same rate, have the same amount of meat and taste the same.
This, at least, is the vision of the US's National Institute of Science and Technology, which has given Origen Therapeutics of Burlingame, California, and Embrex of North Carolina $4.7 million to help fund research. The prospect has alarmed animal welfare groups, who fear it could increase the suffering of farm birds.
That's unlikely to put off the poultry industry, however, which wants disease-resistant birds that grow faster on less food. "Producers would like the same meat quantity but to use reduced inputs to get there," says Mike Fitzgerald of Origen.
To meet this demand, Origen aims to "create an animal that is effectively a clone", he says. Normal cloning doesn't work in birds because eggs can't be removed and implanted. Instead, the company is trying to bulk-grow embryonic stem cells taken from fertilised eggs as soon as they're laid. "The trick is to culture the cells without them starting to differentiate, so they remain pluripotent," says Fitzgerald.
Using a long-established technique, these donor cells will then be injected into the embryo of a freshly laid, fertilised recipient egg, forming a chick that is a "chimera" (see Diagram). Strictly speaking a chimera isn't a clone, because it contains cells from both donor and recipient. But Fitzgerald says it will be enough if, say, 95 per cent of a chicken's body develops from donor cells. "In the poultry world, it doesn't matter if it's not 100 per cent," he says.
With its patent still at application stage, Origen is unwilling to reveal if it can reliably obtain such chimeras. But it has occasionally created the ideal: chicks that are 100 per cent donor-derived, or pure clones.
Another challenge for Origen is to scale up production. To do this, it has teamed up with Embrex, which produces machines that can inject vaccines into up to 50,000 eggs an hour. Embrex is now trying to modify the machines to locate the embryo and inject the cells into precisely the right spot without killing it. Automating the process will be tricky, admits Nandini Mandu of Embrex. Even when it's done by hand, up to 75 per cent of the embryos die.
In future, Origen envisages freezing stem cells from different strains of chicken. If orders come in for a particular strain, millions of eggs could be produced in months or even weeks. At present, maintaining all the varieties the market might call for is too expensive for breeders, and it takes years to breed enough chickens to produce the billions of eggs that farmers need.
Fitzgerald insists that genetic modification isn't on Origen's menu. The stem cells will come from eggs laid by unmodified pedigree birds, he says. All the same, Origen's website says the company has licences for tools for genetically engineering birds, and it talks about engineering birds that lay eggs containing medical drugs.
Animal welfare groups say that it would be cruel if breeders used the technology to mass-produce the fastest-growing birds. Some birds already go lame when bone growth doesn't keep pace with muscle growth. "The last thing they should be doing is increasing growth rates," says Abigail Hall of Britain's Royal Society for the Prevention of Cruelty to Animals.
There are other dangers. If one bird were vulnerable to a disease, all its clones would be too. But if one set of clones fell victim to a disease, the technology would allow farmers to "roll out" a resistant set rapidly.
There could also be benefits for consumers, as farmers could quickly adopt strains that don't carry food-poisoning bacteria such as Salmonella, for instance. Whether shoppers will buy meat from a clone, even if it's not genetically engineered, remains to be seen. And the FDA has yet to decide whether meat and milk from cloned animals is fit for humans.
New Scientist issue: 18 AUGUST 2001
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