Breeding yaks UW researchers seek brisket disease solution

Laramie – At the University of Wyoming (UW), researchers have targeted brisket disease as a result of its impact on ranchers in Wyoming and across the Rocky Mountain West.

“We started working with yaks to understand brisket disease in cattle,” says Mark Stayton, a researcher at UW’s Molecular Biology Department. “Brisket disease is a physiological disease in cattle that’s at least partially genetic. It’s a form of high altitude sickness, and cattle are surprisingly susceptible.”

Over the last 100 years, ranchers have struggled with brisket disease in breeding stock from low altitude herds, so UW utilized genetics from yaks, which are raised on the Tibetan plateau at about 14,000 feet in elevation, to attempt to increase the altitude at which cattle are negatively impacted.

“This project is aimed at exploring the best possible route to treat brisket disease,” Stayton explains.

Early beginnings

Several years ago, Stayton explains the project started with a biochemistry and molecular biology approach.

“Our results did not immediately take us to an understanding of the disease, so we decided three or four years ago to take another approach and bring genes from more altitude-resistant yak into cattle,” Stayton says.

Yak, Bos grunyuns, is a cross-fertile, explains Stayton, with cattle, Bos taurus.

“When we cross yak bulls onto cattle, we hope to transfer some of that genetic resistance into commercial cattle breeds,” he explains. “We have done the first set of crosses, and we certainly will be doing a second set.”

In their first set of trials, UW artificially inseminated a set of Black Angus cows with a yak bull, successfully producing 19 pregnancies. Twelve of the calves were heifers, and seven were bulls.

“It’s well known from both literature and experience in Tibet that the males from this inter-specific cross are sterile,” Stayton says. “So, we will feed out the half-yak steers and slaughter them this winter. We will look at carcass quality and pathology on those steers.”

The heifers will be bred back to Angus bulls, resulting in one-quarter yak progeny.

“We’re going to keep backcrossing the heifer calves to Angus bulls, and we’ll check for altitude resistance with each backcross,” he adds. “Hopefully, each generation will continue to select for animals have retained some altitude resistance. We also hope that each generation will look, act and taste like Angus cattle.”

Results

The initial set of yak-cross calves were pulmonary arterial pressure (PAP) tested to determine their susceptibility to brisket disease.

“In PAP testing, we run a catheter down the jugular of the animal to the heart and the pulmonary artery, which supplies blood to the lungs and measures the blood pressure directly,” he explains, noting lower PAP scores are indicative of animals that are more resistant to altitude disease. “The half-yaks had PAP scores that were halfway between the scores of bovine and yaks. In other words, they are non-reactors to stress from high altitude when compared to bovine calves.”

The initial scores were taken at 7,200 feet. The calves were then taken to 9,600 feet for a month and PAP tested again. The results of the second test are currently being analyzed.

Physical and behavioral attributes

In addition to their anatomical functioning, Stayton noted yaks look very close to cattle, but they can be differentiated by fat, hairy tails and double coats.

“In general, they are shaggier than cattle but not a whole lot,” he says. “They have a double coat, so they have a layer of wool next to their skin and an outer coat.”

The layer of wool protects the yak-cattle crosses against harsh winter weather.

“The yaks don’t mind the cold weather we have, and I haven’t noticed a problem with warm weather in the summer,” Stayton says. “These animals look like cattle from a distance, and I think they’ll begin to look more like cattle with the less yak influence we have.”

Yaks differ from commercial cattle mostly in their behavior.

“The half-yaks are not mean, but they’re more curious, exploratory and athletic, so they can jump over any of our fences,” Stayton comments. “They can be handled just like bovine, although they’re a little more wild. Doing PAP testing requires a little more of a wrestling match, but it can be done.”

Stayton emphasizes, “Behavior is the biggest difference between the yaks and cattle.”

Cooperators

Without the help of cooperators, Stayton notes the research would be much more difficult.

“Bill Gross is one of our cooperators, and he will feed out the steers in Pine Bluffs,” Stayton says. “We have another cooperator in western Nebraska.”

Travis Smith, UW beef unit manager, and his crew have been integral in handling the cattle, and research has been conducted with the assistance of Laramie Research and Extension Center Manager Doug Zalesky and UW Extension Livestock Specialist Scott Lake.

“Rich McCormack, a retired animal science professor, helped to get this project started,” Stayton adds. “We have also received funding from the State of Wyoming to conduct this research.”

Look for future articles this spring about carcass quality and the second round of PAP testing in yak-cow crosses.

Saige Albert is managing editor of the Wyoming Livestock Roundup. Send comments on this article to saige@wylr.net.