A beef cow’s geographic experience affects its grazing behavior and diet choices in the desert rangeland pastures of southern New Mexico, say Derek Bailey and Milt Thomas of New Mexico State University’s animal and range science department.
They used GPS technology to compare the grazing distribution patterns and quality of forage selected by three groups of Brangus cows at the university’s Chihuahuan Desert Rangeland Research Center (CDRRC) near Las Cruces. The three groups were:
“In the extensive rangeland pastures of New Mexico and the West, there are many areas far from water, up steep slopes or at higher elevations that are grazed lightly or not at all, while other areas near water or on gentle slopes are often overgrazed,” says Bailey, who is also director of the CDRRC. “If we can find animals that are more willing to walk farther from water and use pastures on steeper slopes and at higher elevations, we can make grazing in those areas more sustainable, and ranchers will be able to graze more livestock in them. This approach is cheaper than adding water or building fences to extend grazing areas.
“CDRRC pastures are very large, some over 9,000 acres,” he adds. “The GPS collars allow us to watch where the cattle go and see how well they forage, how far they can walk for water and how well they can cover the landscape. We can determine their adaptability and how sustainable the grazing from these particular animals is.
“We know from the CDRRC's multigenerational Brangus breeding program that, in general, Brangus cattle, which are three-eighths Brahman and five-eighths Angus, are well-adapted to harsh desert rangelands. But this study documented that native Brangus cows, those living their entire lives in the desert, had advantages over the other two groups.”
Native cows spent more time away from water, periods ranging from 24 to 48 hours, while naive and tourist cows spent 24 hours or less away from water, he reports. Also, native cows grazed and used areas farther away from water than either naive or tourist cows. Naive cows, with no prior desert experience, used the least area and stayed closest to water.
The researchers found that cows with extensive desert experience – both native and tourist – chose a more nutritious diet during drought conditions than naive cows.
Information from this study can be important for livestock producers making herd-stocking choices and decisions about sustainable rangeland management, says Bailey.
“We can recommend that ranchers using desert rangelands stock at levels allowing them to keep a core herd of cows adapted to this environment in drought conditions so those cows can produce their own replacements,” he says. “If ranchers purchase new animals, we suggest they choose animals developed with forages and environments similar to a rancher's location.”