NMSU collaboration focuses on genetics of hypertension in cattle at Valles Caldera

Sep 3, 2010
by WLJ

The nation’s highest altitude beef cattle research facility, managed by New Mexico State University (NMSU) at the Valles Caldera National Preserve in northern New Mexico, is determining if there are DNA markers that will identify if cattle are genetically predisposed to develop hypertension while at high el evations.

Cattle, like humans, can be genetically predisposed for hypertension at higher altitudes, known as bovine high altitude disease (HAD) or brisket disease, when they graze above 7,000-feet elevation for extended periods.

The inability to process oxygen efficiently is a key health issue that hampers beef cattle operations in the Rocky Mountain region.

“Grazing cattle at high elevations comes with inherent risk due to their susceptibility of developing hypertension,” said Manny Encinias, a beef cattle specialist with NMSU’s Cooperative Extension Service and director of operations for the high altitude research facility.

Most cattle producers don’t know if individual cattle will have problems grazing at high elevations until the animal shows clinical symptoms. Unfortunately, in most situations, the discovery and disease confirmation is only after the death of the animal. Death and performance losses associated with HAD annually add up to more than $60 million for the beef cattle industry in the Rocky Mountain region.

“Our long-term goal at this facility is to develop indicators and tools that beef producers can use to select cattle that will thrive at high elevations,” said Encinias. “We believe high altitude disease is a condition impacted by multiple factors and teaming up with multidiscipline experts, universities and progressive beef cattle producers is a key to making rapid progress on managing this disease.”

NMSU’s College of Agricultural, Consumer and Environmental Sciences is coordinating the facility that involves researchers from three universities—NMSU, Colorado State University (CSU) and the University of Illinois—and cattle breeders from several states.

National expert on bovine HAD Tim Holt, a veterinarian and assistant professor at CSU’s School of Veterinary Medicine and Biomedical Science, has been actively involved at the facility since 2009 by performing pulmonary arterial pressure (PAP) tests on cattle to evaluate individual adaptation to the high altitude.

The PAP test is presently the beef industry’s diagnostic tool of choice as it detects early signs of hypertension through an animal’s blood pressure.

Establishing this research program at the preserve has given Encinias and Holt the most unique venue in the U.S. to study HAD.

“Mountain grazing is a high stress environment for cattle. The higher the elevation, the more accurate the PAP test data,” said Holt. “This is why the Valles Caldera National Preserve is such an important place to conduct this research.”

At more than 8,500 feet in elevation, the Top of the Valle research facility is the highest centralized facility in the U.S. focused on studying HAD. Abundant and highly nutritional grass also provides a natural grazing environment that is a typical grazing scenario beef cattle encounter grazing high altitude pastures.

“The Valles Caldera gives us altitude and a natural grazing environment to evaluate numerous factors and scenarios to better understand HAD,” said Encinias.

“We are interested in nutrition, environment, water and anything else that might be influencing a low oxygen setting,” said Holt. “We are also looking at the pregnancy rate to see if the elevation is impacting the reproductive process, such as if the cow is not pregnant after insemination, do they have high PAP scores? Is that a factor to their not being pregnant?” The newest addition to the research team is genetics researcher Jonathan Beever, associate professor at the University of Illinois’ Department of Animal Science. Beever’s research has been instrumental in the development of diagnostic tools to rapidly detect genetic disorders in multiple breeds of beef cattle.

At the Top of the Valle facility, Beever is analyzing DNA samples gathered from the cattle during the PAP testing process to determine genes that influence the susceptibility to the potentially deadly condition.

Beever is comparing genetic information from animals that are suffering from HAD to those who are not showing signs when given the PAP test.

“The PAP test has become relatively straightforward at identifying animals having problems,” said Beever.

“This disease is clearly a genetic issue and with today’s technology, we have the potential to identify the gene or a group of genes where a variation of genes might influence the animal’s disposition to not have high altitude disease.”

The PAP test is a detection tool, however, not all cattle can be tested before the disease is deadly. The genetic test would be easier to administer.

“With the DNA marker information, we would be able to test any animal regardless of where it is raised, or its pedigree, and be able to say whether this animal will survive when you take him to a higher altitude,” said Beever.

Establishing the research facility at the Valles Caldera National Preserve has also given seedstock producers throughout the U.S. the opportunity to send bulls and heifers for the summer grazing season to the facility and begin to better understand the impact that genetic pedigree and previous management practices have on the animals’ ability to perform at higher altitudes.

With approximately 1.5 million cattle living above 7,000 feet elevation, Roy Hartzog of Hartzog Angus Cattle in Bovina, TX, who has sent bulls and heifers to the research facility for the last two years, says this research will benefit the entire western region.

“We have learned from ranchers who live and have cattle above 8,000 feet that if they don’t use the right bull, one without the genetic predisposition for HAD, when the calves are born, they may die within a week to 10 days. This is the equivalent of a hail storm destroying a cotton farmer’s crop,” Hartzog said, adding that there is no government disaster program for this situation to offset the financial loss.

“We need to provide those ranchers with bulls that are adapted to high elevation. In order to do that, we need to develop our blood lines for a genetic pool that can survive and thrive in high altitude,” he said. “Up until now, ranchers have just had to use a natural selection process and suffer the consequences.”

On Saturday, Sept. 11, the Top of the Valle will host its second annual high altitude bull and female sale. This year, 35 registered yearling and 2-year-old bulls, as well as 70 registered bred heifers that have been PAP and performance-tested on 100 percent grass for 84 days, qualified for the annual sale at the Valles Caldera National Preserve. The silent auction will be held from 10 a.m. to 2 p.m. and a live animal bid-off will begin at 2 p.m. More information on the program and sale is available on the program’s website at http://highcoun trybeef.nmsu.edu. — WLJ