Why did the researchers cross the barnyard?
As chickens get fatter, they're being studied for clues to human obesity.
In this land of bulging waistlines and mega-portions, it turns out we're not the only ones getting fat. Want a hint?
Cluck, cluck. Yes, the chicken. You may not see the impact on your grocer's shelf, since most of the fatty stuff is cut off and the remaining meat is lean.
Researchers at the U.S. Department of Agriculture and Pennsylvania State University are nevertheless studying ways to limit excess fat, for three reasons. Producers don't want to waste feed. Fatter chickens might not lay as many eggs. And studying the genes of the barnyard bird may illuminate pathways that lead to human obesity, says the USDA's Monika Proszkowiec-Weglarz.
Fat content has risen because chickens have been bred to grow faster, and the faster-growing birds seem to eat more than they need, says her colleague Mark Richards.
The USDA-Penn State team is focusing on the role of AMPK, an enzyme that senses energy levels in a wide range of organisms. They've located the gene for AMPK in chickens, and found the enzyme in the bird's hypothalamus - the part of the brain that regulates food intake and energy usage.
The fattest birds are the broiler breeders - the long-lived ones that lay the eggs that hatch into the chickens we eat. But even the young have issues.
A North Carolina State University study found that 43-day-old female broilers from 2001 had five times as much abdominal fat as those from 1957, as a percentage of body weight. That was partly due to change in diet, but the basic birds were also different.
The answer may be to modify chicken diets.
Says Richards: "Ideally, it would be great to allow everybody to self-regulate. Unfortu- nately that doesn't work in people. It doesn't work in chickens, either."
- Tom Avril