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Enriching range cattle diet tough call

Desert rangeland forage base may be adequate in spring and early summer, but over the rest of the year, the quality of the resource begins to decline.

Enriching range cattle diet tough call

Desert rangeland forage base may be adequate in spring and early summer, but over the rest of the year, the quality of the resource begins to decline.

That means what the cow is getting isn’t the same quality of nutrition year-round, explains University of Idaho livestock and range educator Scott Jensen.

The problem is during the growing season, forages from native range provide the only source of nutrition for most beef cows throughout the Intermountain West, he says. “As range forages mature during the summer and fall, fiber content increases, while forage protein and digestibility decrease.

“Trace mineral concentrations in forage plants vary significantly at different stages of the growing season. In many situations, supplementation of cattle consuming low-quality forages is necessary in order to maintain production,” he says.

Western cow-calf producers face a “major problem” determining when and how to supplement low-quality forages as a result, he says, since information on what the basal diet consists of is hard to determine. “You can look up what may be needed in books, but it is far more difficult to go out into a particular rangeland pasture and know what is really there,” says Jensen.

In a project to help develop a low-cost supplementation strategy, Jensen hopes to bring a clearer understanding of what producers need to do to maintain the best health of their cattle.

Complicating the effort is how cattle move from lower to higher pasture in any particular grazing season. As they move higher, the range plant makeup they dine on will change, and along with it, the supplementation needs, he says.

Key Points

• Cattle diets on Idaho desert range are low in copper and high in iron.

• Figuring out how to supplement range cattle’s diets is a hard call for producers.

• New research results may help ranchers make supplementation decisions.

Seasonal variation tests

“What we are trying to do is characterize the seasonal effects on forage concentrations of crude protein, total digestible nutrients and various minerals consumed by cows desert rangeland in southwest Idaho,” he says. It is hoped the work will help determine the appropriate timing of supplementation.

“The ability of a beef cow to perform on Western rangelands depends on three factors,” he says. They include nutrient concentration and availability in forage, forage intake and nutritional needs of the animal.

To help find answers to proper supplementation, he sampled cows in the Jordan Valley area. The two-year study has increased knowledge regarding nutrient concentration of native range plants in relation to the changing grazing seasons, and compared to the cows’ nutrient requirements,” he reports.

“Long-term outcomes include improved protein and mineral supplementation strategies, which should lead to improved herd health and reproductive efficiency.” He reports that animals “do a lot better job selecting than we thought,” when it comes to choosing range plants to eat.

He also discovered a need for copper in diets when grazing, he says. And he found that high iron contents in the cattle may inhibit mineral interactions.

Overall, the cattle met crude protein and energy needs, while lacking about 50% of the necessary copper.

Zinc was also “pretty low,” he adds.

To learn more, contact Jensen at 208-896-4104 or by e-mail at

This article published in the January, 2010 edition of WESTERN FARMER-STOCKMAN.

All rights reserved. Copyright Farm Progress Cos. 2010.

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