N.C. State researchers to study genetics of heat tolerance in poultry

Media Contact: Dr. Chris Ashwell, 919.513.7335

In the South, where most of the meat-producing poultry in the United States is raised, summer is a tough time. Poultry producers can count on losing some of their birds to heat stress.

Poultry science researchers at N.C. State University and two other institutions are hoping to learn more about the genetic traits and responses that could help poultry better cope with heat stress. Such knowledge will help poultry producers around the world plan for rising temperatures from global climate change.

The 5-year research project will be funded by a $4.7 million grant from the U.S. Department of Agriculture’s Agriculture and Food Research Initiative (AFRI). In addition to N.C. State, other participating institutions are the University of Delaware, Iowa State, the University of Liverpool and Iowa-based Hy-Line International, the largest breeder of egg-laying chickens in the nation.

Dr. Chris Ashwell, N.C. State associate professor of animal genomics in poultry science, believes this is the largest competitive USDA grant ever awarded to study poultry.

Ashwell is investigating whether epigenetics could play a role in how chickens react to heat stress. A relatively new science, epigenetics explores how environmental stresses can affect the expression – or suppression – of certain genes.

The field of epigenetics “has exploded in the last three years,” Ashwell said. “Ten years ago we were all looking for mutations; no one was thinking about epigenetics.”

Scientists have long assumed that genetic codes could be altered over time, but that true genetic evolution would take many generations. Epigenetics examines how a stressor like heat or hunger can alter the expression of certain genes. And that alteration can actually be transmitted to subsequent generations. If the stressor is removed, eventually the genes will return to their normal function.

Ashwell says that one analogy of epigenetics is a text document, built around 26 letters of the alphabet. The text can be expressed in different ways with a key stroke – bold, italics, smaller or larger fonts. In the same way, the genetic code of an organism – even in identical twins with the same genetic code – can be expressed in different ways without ever changing the content of the information.

Some evidence suggests that when chickens or turkeys are exposed to high temperatures within the first few days of life, they have a much higher tolerance to heat stress experienced later in life. If increased heat tolerance in poultry was caused by an epigenetic shift, perhaps it could be transmitted to future generations.

Animal studies for the project will be based in Delaware and Iowa, so Ashwell and his colleagues will travel to those states to collect samples and data. N.C. State researchers will collect poultry DNA and physiological data such as birds’ body temperature and feed consumption.

Delaware researchers will study poultry RNA, and Iowa researchers will look for genetic variants associated with heat tolerance.

In the fourth year of the study, researchers will travel to the African countries of Kenya, Uganda and South Africa to sample DNA from poultry flocks in rural areas. They will look for genetic traits that may help those birds tolerate extreme heat because little data is available on native poultry populations in developing countries, Ashwell said.

If the researchers discover that African birds have genes for heat tolerance, those traits could be bred into poultry lines produced here.

The impact of this research for poultry producers in the U.S. would be reduced mortality in summer when temperatures are higher, or when there is acute stress to birds from a power outage that shuts down cooling systems in poultry houses.

–Written by Natalie Hampton, 919.513.3128