Most Montana cattle probably don't get enough copper and zinc, said an expert at Montana State University. Even in good forage years, Montana's legumes and grasses are often deficient in these key trace minerals, said John Paterson, a beef specialist with the MSU Extension Service.
 

Cattle need trace minerals for vitamin synthesis, hormone production, enzyme activity, collagen formation, tissue synthesis, oxygen transport, energy production and other physiological processes related to growth, reproduction and health, said Paterson in a recent issue of the "Beef: Questions and Answers" newsletter.
 

Recent liver biopsies from cattle in southwest Montana suggest that 39 percent of the cattle surveyed did not have adequate levels of copper in the liver. However, cautioned Paterson, cattle in eastern Montana might have levels more similar to western North and South Dakota, where up to 92 percent of cows were found to have inadequate copper amounts in the liver.
 

 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, said Paterson.  "I also believe that much of the foot-rot I see in Montana is related to trace mineral deficiencies," said Paterson. "Zinc and iodine supplementation appears to cure the problem."
 

In a Montana survey from a few years ago, most grasses, legumes and forage mixes were found to be deficient in both copper and zinc. In addition, the survey found some high ration of molybdenum, which can further decrease the animal's absorption of copper.
 

Water can also be a factor. Paterson said several water samples from central Montana showed sulfate levels that were up to eight times higher than recommended. Such a high ratio can also reduce the animal's utilization of copper.
 

Livestock producers who are concerned about trace mineral levels in their herds should analyze forages and livestock water for mineral content, said Paterson, particularly if cows are experiencing delayed or abnormal estrus, or other reproductive health problems.