Bacteria + Virus + Stress = Disease State?

Bacteria + Virus + Stress = Disease State?

calf University of Idaho scientists Jim England, Beth Mamer, Al Ward, and Glen Weiser are looking closely into variables of that equation. Currently in the third year of a 3- to 5-year project, beef calves are being monitored to determine which pathogens are responsible for respiratory diseases that occur between 30 to 180 days of age. Photo by Mark LaMoreaux.

Thirty calves each year from among a heard of 230 cows are studied.

“There are well-identified causes for respiratory disease in calves younger than 30 days or past weaning age, but the causative agents for this age group are less definitive,” explains England. The University of Idaho’s Nancy M. Cummings Research, Extension and Education Center near Salmon is an ideal research facility for these experiments because it is a high mountain, natural location facing environmental challenges similar to other open-range cattle ranches in the state.

Annual losses at least $3 million
Idaho ranchers routinely experience losses of more than $3 million a year through a combination of increased costs for treatment, labor, diminished or delayed weight gains, and mortality.

Understanding what organisms are found in healthy calves is the first step. The first two years of research confirmed that five suspected pathogens are present in both sick and normal calves. A sixth one, Pasteurella trehalosi, may be the, or at least is a culprit.

“This bacterium has been associated with respiratory disease in wild ruminants and we have isolated it more often from clinical cases of bovine respiratory disease,” says England, who adds its significance “remains to be defined.”

Good health of the calves has thwarted a second project goal—to sample calves with pneumonia or other respiratory distress symptoms. “We’ve had maybe one sick calf a year. Statistically, that’s not significant enough,” says England.

Tracking health of the herd across seasons and monitoring domestic animal–wildlife interactions in the same facility allow researchers to consider a wide range of factors in overall health of individual animals.

Scientists can then recommend improved preventive measures, treatments, and management techniques. “Ranchers will benefit from healthier animals, healthier profit/loss margins, and a better end product,” says England.

--Candace Akins