A link found between estrus-suppressing drugs and pneumonia in cattle
could help feedlot operators cut losses in market-ready animals.
In a three-year study, Tim McAllister of the Agriculture Canada
Research Centre in Lethbridge found a link between heifer losses to
atypical interstitial pneumonia, or AIP, and the commonly fed
estrus-suppressing drug melengestrol acetate, or MGA.
Eliminating MGA from the diet reduced the risk of contracting AIP,
McAllister reported.
MGA is commonly given to heifers to keep them from mounting in pens,
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decrease damage to animals and maintain good weight gains, said Glenn
Coulter, the centre’s assistant director.
He said the disease affects less than one percent of cattle.
“It’s not a big problem, but you can lose five or seven animals per pen
at once,” Coulter said.
He expected there will be further study to better understand what is
happening and how it relates to weather factors.
The studies, which took place at the Lethbridge research centre,
southern Alberta feedlots, Alberta Agriculture, Ohio State University
and the University of Utah, also found that acetylsalicylic acid, or
ASA, could increase the short-term life expectancy of cattle with the
disease.
Researchers studied plasma, urine, lung tissue and rumen fluid from
slaughtered animals diagnosed with AIP and compared them with similar
samples from healthy animals given a host of experimental treatments.
They found heifers were more susceptible to AIP than steers.
McAllister believes MGA may increase the levels of an enzyme believed
to damage the lungs and lead to pneumonia in heifers at body weights of
around 1,000 pounds.
It causes symptoms such as frothing at the mouth, lowering of the head,
increases in respiration and grunting.
Gary Sargent, general manager of the Alberta Cattle Commission, called
it a troublesome disease, which struck the Picture Butte district two
years ago.
“People were experiencing losses and didn’t have an idea,” he said. “At
least now they will have some idea where to look.”
Sargent said producers concerned about the disease launched the
$210,000 project that studied 900,000 cattle. Funding came from the
Canada Alberta Beef Industry Development Fund, which was designed to
tackle problems facing Alberta beef producers and is administered by
the ACC.
