Details in Agricultural Research magazine.

Reducing Heart Problems in Chickens

Agricultural Research Service scientists have made recent strides to prevent a fatal heart condition, called ascites, that can cost U.S. poultry producers $100 million a year in losses.

When a chicken gets ascites, the right ventricle of its heart enlarges and can’t pump blood efficiently to the chicken’s lungs. Blood pressure then builds in the liver and a yellow serum-like fluid leaks from the liver into the body cavity, eventually leading to death.

It takes six weeks for birds to grow large enough to go market, and they are genetically selected for this fast growth rate. Their hearts and lungs have to work harder to keep up with the increase in metabolic requirements, and some birds just can’t keep up--leading to ascites.

Birds raised at high altitudes often get ascites. So poultry physiologist Janice M. Balog at the ARS Poultry Production and Product Safety Research Unit in Fayetteville, Ark., uses a hypobaric chamber to simulate higher altitudes. Then she identifies and selectively breeds ascites-resistant and ascites-susceptible birds.

In the fourth year of her study, Balog and University of Arkansas poultry geneticist Nicholas Anthony have selected over four generations for broilers that are resistant or highly susceptible to this disease. The resistant population exhibits no more than 20 percent ascites at simulated high altitudes, while the susceptible line has greater than 80 percent ascites.

To control ascites, producers now restrict feed, which slows down birds’ growth and reduces mortality. But these birds take longer to reach market weight and can have less white meat, the most valuable part of the chicken. Poultry producers can also reduce the incidence of ascites by maintaining optimal temperatures or by increasing ventilation in their poultry houses, which improves air quality.

An article about this research appears in the May issue of Agricultural Research magazine. The story is also on the World Wide Web.

ARS is the chief scientific agency of the U.S. Department of Agriculture.

Scientific contact: Janice M. Balog, ARS Poultry Production and Product Safety Research Unit, Fayetteville, Ark.; phone (501) 575-6299, fax (501) 575-4202, jbalog@comp.uark.edu.