Doppler Ultrasound Helps Scientists Understand Fescue
Toxicosis in Cattle
October 20, 2009
Doppler technologythe very
same technology used by meteorologists to track thunderstormsis being
used by Agricultural Research Service
(ARS) scientists to better understand the rate at which fescue toxicosis
restricts blood flow in cattle.
Tall fescue is the predominant grass used for grazing in the United States.
But more than 80 percent of the tall fescue in the "Fescue Belt"
regionthe transition zone between the temperate north and the subtropical
southis infected with an endophytic fungus. Once consumed, the fungus
produces ergot alkaloid toxins that cause fescue toxicosis in grazing animals,
costing the livestock industry nearly $1 billion annually in lost production.
Doppler ultrasound technology is being used by researchers at the ARS
Animal Production Research Unit (FAPRU) in Lexington, Ky., to help better
understand the causes of fescue toxicosis and to expedite development of
management approaches to alleviate it. The research is led by animal scientist
Aiken. FAPRU research leader
Strickland was a collaborator in the project.
The ergot alkaloids in tall fescue constrict blood flow. Using the Doppler
technology, the ARS scientists found that blood flow decreases within 24 hours
of feeding cattle ergot alkaloids. Results show that in cattle consuming diets
containing ergot alkaloids, blood flow through the caudal arterywhich
supplies blood to the tailcan be reduced by as much as 50 percent
compared to cattle on alkaloid-free diets. Constricted blood flow to peripheral
tissues, such as the tail, reduces the animal's ability to dissipate body heat,
making it vulnerable to heat stress.
The research has helped the scientists better understand ergot alkaloids and
the mechanisms by which they cause toxicosis. This knowledge could lead to
improved forage and animal-management protocols that decrease exposure or
enhance tolerance to the alkaloids of endophyte-infected tall fescue.
ARS is the U.S. Department
of Agriculture's principal intramural scientific research agency.