Brucellosis reduces pregnancy say
USU ecologists
Date: October 29, 2018
Source: S.J. & Jessie E. Quinney College of
Natural Resources, Utah State University
For decades researchers have
known that a bacterial disease in elk, bison and cattle in the Greater
Yellowstone Ecosystem causes periodic abortions in these animals and chronic
illness in humans drinking infected cow's milk. The disease, called
brucellosis, poses a financial concern for dairy producers and cattle ranchers,
but its effects on the wild elk population have generally been considered
minor.
In recent years, however, elk
pregnancy rates have become the subject of controversy. Various researchers
claim that stress caused by fear of wolves and nutritional deficiencies caused
by drought can explain low pregnancy rates in specific elk herds, but until now
the effects of brucellosis on elk pregnancy have not been scrutinized.
Utah State University researchers
Gavin Cotterill and Johan du Toit report that by mid-winter, elk that test
positive for brucellosis are less likely to be pregnant than healthy elk,
independent from the abortions caused by that disease later in the year.
Cotterill and du Toit, along with colleagues from the Wyoming Game and Fish
Department, US Geological Survey Northern Rocky Mountain Science Center, and
University of California Berkeley, discuss their findings in Ecology and
Evolution published 28 October 2018.
"Mid-winter elk pregnancy
rates are often seen as an indicator of an elk herd's health and
viability," says Cotterill, a PhD candidate at USU and lead author of the
paper. "If we're interested in figuring out the effect that predators or
climate are having on elk we need to also account for disease."
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