Skip to comments.Best in Breed
Posted on 01/28/2002 10:29:48 AM PST by Junior
Remarkable progress has been made in the production of food - bigger chickens, more eggs, more milk -- and biotechnology has nothing to do with it. It's all due to techniques people have been using since the 18th century. STEPHEN STRAUSS reports
When people talk of scientific revolutions, they evoke the names of Galileo, Newton, Darwin, Einstein, but never Gallus gallus domesticus.
It's because Gallus, a.k.a. the common chicken, is the physical expression of a revolution that has been largely hidden from popular consciousness.
Consider for a moment that in the wilds of India and Bangladesh, the four colourful progenitors of today's farmed chickens wander around scavenging earthworms, pecking at insects and swallowing up the occasional bits of grain they sneak from farmers' fields. In their native, untamed state, the Red Jungle Fowl, the Green Jungle Fowl, the Cylon Fowl or the Gray Jungle Fowl lay six to 12 eggs a year.
This number nudges up only slightly when wild chickens are raised according to traditional rearing and feeding practices. The indigenous domesticated chickens of Bangladesh, which in addition to whatever they can scavenge are given some rice bran, rice gruel and cooked rice, will lay three or so eggs a month that weigh, on average, 35 to 39 grams.
Then reflect on the modern chicken.
In North America, eggs of 35 grams are so small as to be classed as "peewee," -- a weight so minuscule that Craig Hunter, vice-president of operations for giant Burnbrae Farms, says that "they wouldn't be saleable." Indeed, they are almost exactly half the size of the large eggs that are currently found in supermarkets.
But small egg size is merely a small part of a big equation about egg improvement. In 1910, the average North American chicken produced roughly 84 eggs a year on a seasonally attuned schedule that saw most eggs laid in the spring and summer. In 1932, the gross yearly egg number had gone up to 100. Today, in countries such as China and Vietnam, where selection and feeding are less scientific, 200 eggs a year is considered a good yield -- a number Hunter says would have been similar to that obtained in Canada in the 1960s.
By 1983, eggs were popping out of an average chicken in this country at a rate of of 247 eggs. In 1999, that had increased to 292, and individual chickens have been recorded that laid an egg a day for a year, and 500 over their lifetime.
Not only are they laying eggs at roughly 30 times the yearly rate of their their wild forebears, but they start younger. The average age at which the semi-wild chickens of Bangladesh begin to reproduce is 28 weeks. In the highly selected chickens of North America, eggs begin appearing at 18 weeks.
At the same time, the amount of food you have to feed a chicken to produce the egg has fallen from 2.8 kilos of feed to produce one kilo of eggs 30 or 40 years ago to 1.8 kilos to produce a kilo of eggs today.
The modern chicken is a symbol of what has occurred across a whole range of animal farming without being noticed much by the 98 per cent of Canadians who aren't farmers.
In an era replete with prophecies about the potential effects -- for good or for ill -- of selectively moving individual genes around in the DNA of food animals, few people outside agriculture have been paying much attention to how dramatically the genetic-modification equivalent of a hammer and a nail has changed, and continues to change, the food we eat.
"I don't think that if you had told the average farmer 150 years ago where we are today, he would have believed you," says Jacques Chesnais, general manager of the Canadian Centre for Swine Improvement.
Moreover, even though improvements have taken place slowly for thousands of years, over the past 50 years the rate of change has actually been increasing so dramatically that in many ways the people involved can't believe what they have accomplished.
"People have thought that we would have reached a plateau and we wouldn't be able to go further, but, in fact, we have been experiencing an accelerating rate of progress," Chesnais says.
What is equally astonishing about the alterations in farm animals is that the basic tools for this revolution have been versions of the techniques people have been using without controversy since scientific agriculture first appeared in the 18th century -- selective breeding and a careful attention to nutrition and health.
But the results are such that if you didn't know how the improvements had been made, you would probably assume that they came from a wholesale reordering of the animals' physical makeup. "If somebody would have said you can increase egg production 25 per cent 25 years ago, people would likely have said, 'That is a noble goal, but I don't think you would get there,' " Hunter says.
They also would not have believed what has taken place with other animals. Broiler chickens present a similar story of increases that seem fantastical.
Until the 1920s, there was no separation of egg-laying and cooking-chicken stock. In 1923, the first year-round, large-scale production of chickens began in the United States, replacing an economy in which, in the words of Michael Lacy of the University of Georgia, "the farm flock was a sideline agricultural enterprise primarily for the purpose of producing eggs, and the production of poultry meat was a sideline of a sideline."
Getting a chicken big enough to eat was slow and inefficient. Initially, it took 4½ kilos of feed to produce about a kilo of chicken -- then the average weight. Getting the birds even to that size took 16 weeks -- and was perilous. By the time the first 500 chickens thus raised were ready for market, disease had killed 113 of them.
Then came the breeding, feeding revolution and by 2000 the same 4½ kilograms of feed was producing 2¼ kilograms of chicken in only seven weeks. And if you start out with 500 chickens, dramatic reductions in sickness means that 475 now make it to market.
If you think chickens are just an aberration, consider Bos primigenius, the ancestor of the modern cow.
The last progenitor of the modern North American cow was an auroch that died in the forests of Poland in 1627. Aurochs stood nearly two metres tall and had a wide sweep of horns not unlike long-horned Texas cattle, but were unproductive when it came to milk. It is estimated that they produced something like 500 litres a year.
Domestication made a significant difference. A few of the Ankole cattle of Africa, which physically resemble the aurochs, can produce up to 1,500 litres of milk a year. In the United States, the average amount of milk per cow increased from about 2,300 litres in 1940 to 7,236 litres a year in 1996.
And the increases continue. From 1990 to 2000, the average yearly milk output of the Brown Swiss, a popular dairy cow, increased by nearly 30 per cent in Canada.
But from the point of the Guinness Book of Records, even those numbers shrink. The most productive cow ever gave nearly 30,000 litres of milk in a year -- 60 times that of a wild cow.
The litany continues wherever you look. In beef cattle, the average cow carcass weighed a bit more than 272 kilograms in 1975 and that had increased to 372 kilograms in 2001. At the same time, the percentage of meat that was top grade increased to 47 per cent in 2001 from 18 per cent in 1992.
Finally, a similar story exists in that legendary receptacle of fatness, pigs, where more than 63 per cent of the meat is classified as lean and it now takes less than half the amount of feed to put on a kilogram of weight as it did in 1980.
But perhaps what is most striking about this "old" revolution in agricultural genetics is how it may be casting a shadow on the new revolution that is supposed to replace it. It is not clear that biotechnology, as currently constituted, will be able to duplicate the virtues of what Jim Wilton, director of the centre for the genetic improvement of livestock at the University of Guelph, calls the "whole animal" approach to genetic manipulation.
He argues that the gross gains in all areas of animal husbandry have been achieved without any drastic indication that an improvement in one area has to be accompanied by a loss in another. "We still have very functional cattle, with good reproductive function and good health status. They are what you might call completely normal animals."
This is because scientists using conventional breeding select not for a single genetic trait -- the state of art of today's biotechnology-based gene transfers -- but rather look at a bundle of desirable characteristics operating in concert within the animal. Thus, scientists select animals that maximize one trait -- milk production, for example -- without drastically upsetting others -- for example, general health, calving numbers.
The question is whether animal biotechnology will ever be able to mimic this. Over the past year, Wilton has begun to argue that classical selective breeding, which operates through the transfer of a suite of genes, might prove to be a superior way of making better farm animals than the supposedly more revolutionary pinpoint approach. "When you move a single gene, you don't know what will happen; selective breeding allows you to choose in a more all-round sense what you want."
With this as a background, there is a belief that the genetic revolution of the future will simply be an extension of the genetic revolution of the past. "The reality is that things which have been improved in livestock have not been due to biotechnology and are unlikely to be due to biotechnology into the foreseeable future," Chesnais says.
And where might that improvement be headed? Less and less food intake continuing to produce more and more animal. Al Kulenkamp, a geneticist with Shaver Poultry Breeding Farms in Cambridge, Ont., points out that a world in which 1.5 kilograms of feed produces one kilogram of eggs seems to be in view.
Indeed, the ultimate limit in food-in/egg-out equation is simply that a chicken body has to allot a certain amount of energy to staying alive and that basic laws of physics say you can't get more weight of eggs out of a chicken than feed you are putting in.
Beyond this, Kulenkamp says that even if nutritional improvements come to an end, there are hopes that through traditional breeding scientists can develop chickens who lay more than an egg a day and in so doing begin to approach the supposed world record -- seven eggs in 24 hours.
But quantity isn't everything. Chesnais imagines conventional breeding efforts being able to graft on to increased litter size and increased eating efficiencies a specifically modern measure of health: A variety of pigs whose bodies are less likely to become resistant to the antibiotics used to cure many of their ills.
A "whole animal" leap in the universe of pigdom.
An average chicken would lay 247 eggs per year.
An average chickenwould lay 292 eggs per year.
A broiler chicken would have an average liveweight of 2 lbs.
A broiler chicken would have an average liveweight of 5.1 lbs.
A Brown Swiss milking cow produces an average of 6,156 kilograms of milk in a year.
A Brown Swiss milking cow produces an average of 7,920 kilograms of milk in a year.
And where might that improvement be headed?How about breeding skinless, boneless chickens? Or chickens bred without heads or central nervous systems, so I don't have to feel guilty about eating the tasty little creatures.
Now that's a great idea- just what we need, more Demorat voters... *grin*
I just had a flashback to that old "Far Side" cartoon about the boneless chicken ranch ...At heart, I am a plagiarist.
Or better, yet, breed chickens that can tell you they want to be eaten:
So... I wonder if domestic chickens can still be bred with the original wild chicken species? (Or would it be more like a Samoan marrying a Hutu?)