WASHINGTON – As turkey breeders produce heavier and heavier birds, the number of fertilized turkey eggs that do not hatch has also grown, causing concern among U.S. Department of Agriculture officials.
About 100 million of the 430 million turkey eggs that were laid in the United States last year did not hatch, a loss of as much as $65 million in potential revenue to turkey farmers, according to the USDA.
Part of the problem is the drive to produce bigger birds for the Thanksgiving table, said Murray R. Bakst, a physiologist with the USDA’s Agricultural Research Service who is studying the trend.
While it is typical for 3 to 5 percent of fertilized turkey eggs not to hatch, he said, larger birds can lose up to 15 percent of their eggs.
“Reproductive systems are not always compatible with growth,” said Wayne Kuenzel, a professor of physiology in the animal and avian sciences department at the University of Maryland, College Park.
“As an animal becomes larger and larger, the reproductive system is compromised,” Kuenzel said.
Over the years, male turkeys have been bred to weigh as much as 85 pounds, making it difficult to breed with a 20-pound hen. Larger hens also produce fewer eggs, and the hatchability rates of those eggs fall.
But the technical director for British United Turkeys of America, one of the three largest turkey-breeding companies in the world, said overall turkeys are efficient in producing offspring.
“The fact that it’s only 25 percent [egg loss] is remarkable,” said Steve Lerner, the technnical director. “But if we understood the biology better, perhaps we’d have a better chance of intervening.”
But, Lerner said, anything that reduces the loss of turkey embryos early on would be a “tremendous benefit” to the industry.
“A 1 percent improvement in fertility is still a great number of turkeys,” he said.
Lerner said the biggest potential to increase hatchability is in the early stages of incubation.
To most efficiently produce turkeys, breeders do not allow hens to hatch their own eggs. Instead, the eggs are hatched in incubators.
But there are far more eggs laid than can be incubated. Eggs that are not incubated immediately are stored at 54 to 55 degrees and at 70 to 80 percent humidity to stop development. Incubation then restarts development.
But some embryos do not start up again and others progress for a few days before dying, Bakst said. Since researchers began looking more closely at unhatched eggs in 1991, he said, they have come to realize that an increasing number were fertilized but that the embryo died before hatching.
To decrease embryonic death, Bakst suggests that eggs be stored at 64 degrees for about three days. They are now stored anywhere from five to 25 days.
Bakst theorizes that fewer embryonic cells remain viable the longer eggs are stored. A minimum of cells must remain viable for an embryo to reactivate its development upon incubation, he said.
Since turkey eggs are generally not eaten, losing nearly 24 percent of fertilized eggs is a big concern for the turkey industry, said Secretary of Agriculture Dan Glickman in a USDA report. He said it is also a big concern “for the many Americans who look forward to turkey each year at their Thanksgiving dinner.”
The National Turkey Federation said Americans consumed 4.7 billion pounds of turkey last year, 34 percent during the holidays.
“You don’t want to pay for a turkey what you’d pay for a sirloin steak,” Bakst said.