Reducing Heart Problems in Chickens By
May 18, 2000
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 cant pump blood efficiently to the chickens 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 cant 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.
Janice M. Balog, ARS
Poultry Production and Product Safety
Research Unit, Fayetteville, Ark.; phone (501) 575-6299, fax (501)