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Bovine High Altitude Disease Studied In New Mexico Cattle

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BOVINE HIGH ALTITUDE
This Sept. 26, 2011 image shows cattle that have been rounded up following a summer of research in Valles Caldera National Preserve, N.M. New Mexico State University's Top of the Valle research center at the preserve has teamed up with researchers from other universities to study bovine high altitude disease, an illness that costs the beef industry some $60 million a year. (AP Photo/Susan Montoya Bryan) | AP

VALLES CALDERA NATIONAL PRESERVE, N.M. -- The lush grass in northern New Mexico provides a strong lure for drought-stricken ranchers looking for a way to feed their animals. But grazing in the mountains brings a risk of bovine high altitude disease, a potentially fatal illness that costs the beef industry some $60 million a year.

As many as 2 million cattle graze on public and private land at high altitudes every summer, but with thousands developing the disease each year, ranchers take a chance when they send their animals into the hills.

To determine which genes are responsible for the illness and what ranchers can do to reduce the chances it will develop, New Mexico State University has established a research facility at the Valles Caldera National Preserve, and ranchers are sending cattle to graze here and be studied.

At a time when ranchers in dry areas of the West and Southwest are choosing between buying expensive hay or selling off animals they can't feed, finding a way to ensure their cattle can safely graze at high altitudes holds a strong attraction.

"Anytime you lose an animal, it obviously cuts into your profits and we're a low margin type of industry and we can't afford losses. That's why this is so relevant," said Manny Encinias, a beef cattle specialist and director of NMSU's Top of the Valle research facility.

High altitude sickness affects cattle much like it does people, who can find themselves gasping for breath and watching their blood pressure rise. In cattle, the inability to process oxygen can result in hypertension, fluid buildup and eventually death.

Encinias is working with Jonathan Beever, a geneticist at the University of Illinois, and Tim Holt, a Colorado State University expert on high altitude disease, to try to find DNA markers that indicate whether certain cattle are predisposed to develop high altitude disease.

He was rounding up cattle recently when he spotted a little black steer with a shaggy coat and droopy ears.

"You can see when he jogs, he has abnormal fluid buildup throughout his abdomen. He's just like a big water balloon," Encinias said after trailing the steer on horseback. All are classic signs of high altitude disease.

It was unlikely the steer would survive the trip to a feed yard or the stress he would feel once there, Encinias said. Researchers planned to have him put down so he could be studied.

They also aim to collect as many blood and DNA samples as possible until their lease at the preserve is up in 2013.

And, they're looking at what steps ranchers can take to reduce cattle's risk, such as adjusting the animals' feed, controlling their weight or reducing their stress from shipping.

Renee Grant, whose family runs Cornerstone Ranch in eastern New Mexico, sent some bulls to the preserve for study this summer. The researchers confirmed what Grant already knew – her family's cattle are accustomed to the mountains and do well at high altitudes. Participation in the project also allowed her to hang on to animals that otherwise would have been too expensive to feed.

"You have to understand, we're in a real drought situation," Grant said. "We've had an inch of rain since last October and what we have received has been in small amounts followed by high winds and high temperatures. We've never greened up this year."

The reasons some cattle thrive at high altitudes and others don't seem to lie in their genes, said Beever, the geneticist. Finding the two or three genes that are responsible would allow ranchers to focus on breeding animals resistant to high altitude sickness and reduce their losses with future generations.

"Not that I'm perpetual optimist, but I think there's absolutely a possibility that we can do something about this one," Beever said.

Holt also has found evidence in his decades of work on high altitude disease that circumstances matter. Tests done as part of the research at Valles Caldera have found up to 30 percent of cattle typically have high blood pressure after 60 days at a high altitude.

This year, less than 20 percent had developed hypertension by that time. The researchers are looking into whether that's because the dry start to the grazing season resulted in the cattle gaining less weight.

Montana cattle breeder Darrell Stevenson said a genetic test would give his customers more certainty about whether the bulls they are buying can survive at a high altitude. Now, all they can do is check the animals' pedigrees and run pulmonary tests after the fact.

"It's all about managing your risk and improving your genetics – all aiming toward more profitability," said Stevenson, whose family owns Stevenson Angus Ranch.

Encinias said the work also could improve the food consumers eat.

"Research has shown time and time again that low stress improves the quality of the beef that ultimately ends up on someone's plate," he said. "That's an important thing to drive home. If we can identify some indicators and tools through this research to help reduce stress, we're helping the greater industry to produce better beef."

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