“Farmers grow for what the consumer wants—and that includes meatier turkeys,” said Keith Williams of the National Turkey Federation. “The live weights of turkeys, due to that consumer desire, has continued to grow, and the amount of feed to raise each pound of turkey continues to be less.”
Less feed reduces farmers’ costs, and it has environmental benefits, too, as less corn and soybeans are required to meet the nation’s turkey demand. And that demand has gone up a lot. In 1950, America’s per-capita turkey consumption was just 5.5 pounds. Nowadays, that number is upwards of 16 pounds, and the National Turkey Federation would like to see it grow to 20 pounds, which would beat the industry’s peak consumption of 18.2 pounds of turkey per American in 1996.
Turkeys are no different from other livestock. Chickens have undergone a very similar process. Cows used to produce 5,000 pounds of milk. Now they produce more than 20,000 pounds. Selective-breeding programs combined with the development of quantitative genetics have created systems for morphing our livestock to better fit the market.
For all of these breeding programs, the key technology has been artificial insemination. A given male with the kinds of traits that breeders are looking for can be mated to many, many, many females. One bull, Pawnee Farm Arlinda Chief, had 2 million great-granddaughters, and is responsible for 14 percent of all the genetic material in Holstein cows.
Although these programs are analogous to humans’ original domestication of these animals, it is different enough in degree to become different in type. This is market-driven hyper-domestication.
And there are trade-offs. While turkeys’ overall mortality rates do not seem to be higher than earlier generations, they—like our ever-larger chickens—do suffer some new kinds of health problems. Their bodies can struggle to hold up their weight, leading to leg problems. And sometimes breeding exclusively for size can have a negative effect on animals’ fitness and fertility, which was an unintended side effect. Poultry scientists now say that “fitness traits must be measured and incorporated into selection objectives.”
In turkeys, pure body-weight growth has been decelerating. In the 1980s, turkeys put on an average of .25 pounds a year. In the 1990s, that shot up to .41 pounds. In the 2000s, the number was down to .33. And this decade, we’re looking at .22 pounds a year so far.
At some point, the growth of these birds will hit a market or a genetic limit, but it’s an open question which one they will reach first.