by Nancy Carver Singleton

Great Plains forages are often deficient in copper and zinc, placing cattle at risk for poor reproductive performance and immune function, according to beef experts..

A deficiency in copper or zinc can delay estrus, decrease conception rates, and increase dystocia in cows and decrease libido, delay puberty and impair growth in bulls. Along with that, much of the foot rot he sees is related to trace mineral deficiencies, said John Paterson, a beef specialist with Montana State Extension Service.

Livestock producers who suspect mineral deficiencies should analyze forages and livestock water for trace minerals, Paterson advised. That is especially important if cows are experiencing delayed or abnormal estrus or other reproductive health problems.

He oversaw a study several years ago that looked at copper levels in 1,200 cattle among eight Great Plains states. Liver biopsy is the best indicator of copper status, with a liver concentration of less than 90 parts per million (ppm) considered less than adequate. Less than 30 ppm is considered severely deficient.

Testing showed the following percentages of cattle sampled per state had less than 90 ppm in the liver: Colorado, 70 percent; Kansas, 49 percent; Missouri, 27 percent; Montana, 39 percent; Nebraska, 88 percent; North Dakota, 100 percent; South Dakota, 73 percent; and Texas, 38 percent.

He explained that beef specialists have known for years that low levels of zinc and copper cause health problems. The problem was "how to supplement around" the low levels. "I believe that we have made great progress in the last 10 years in learning how to supplement western range cattle," Paterson said.

Recent research suggests that iron inhibits copper metabolism. "This has been evident during the recent years of drought when the sulfate levels seem to have been much higher in water samples," he said. Because minerals become more concentrated during a drought, it is especially important then to check sulfate levels in water samples. (See a related article on sulfate levels in water on pages 32-33).

Even in years with adequate rainfall, copper and zinc are often deficient in Montana grass-legume hays. The same is likely true for the other Great Plains states in the survey, Paterson said.

Since protein and energy levels can also cause problems, Paterson first tries to identify the symptoms.

"I play detective, trying to find out the problems. 'Have you had an increase in respiratory problems, increased scours, black cattle hair turning red, increased foot rot, decreased reproduction and an increase in morbidity of weaned calves when they get to the feedlot? Tell me about your vaccination programs? Tell me about the current mineral program you are using.'" Paterson said.

The number of off-the-shelf supplements for low copper and zinc has increased substantially in recent years. They are sold under a variety of names such as BioRange, Onyx, Ultramine 12-12 and Snowy Mountain Minerals. Most work fairly well, he said.

A nutritionist or feed company can also blend a custom-formulated trace mineral supplement. "One of the things I like about Montana is that they (feed companies) will do custom formulations for ranchers," Paterson said, adding that many ranchers buy two tons of supplement at a time.

There can be a considerable cost difference in cost for the custom-blended supplements. "I say, 'I want 20 percent of the supplement to be organic, 80 percent inorganic. Give me a bid,'" Paterson said. When he recently got three bids, there was a $40 per ton difference between the top and low bids.

Overall, Paterson thinks there is a growing trend in the Great Plains for supplementing low copper levels. Much of that is due to research financed by the mineral firms that supply feed companies. "I think they've helped bring awareness up," he said. ©