I know you realize that copper is a trace mineral and it is required by your livestock as well as in your diet. It is a mineral that is quite deficient in Pacific Northwest forages, hays, straws, grains, by-products and almost anything else you might feed your cattle. Copper is an essential part of many different enzymes. Symptoms indicating
a deficiency of copper include the following;

  1. infertility
  2. depigmentation of haircoat. black – off color grey; red –washed out orange ) wiry appearing haircoat
  3. diarrhea
  4. lack of appetite and growth
  5. broken bones
Copper toxicity is not normally seen and is hard to identify because there are no characteristic symptoms. Dead animals are observed, red blood cells are destroyed, and high liver copper levels are found when liver biopsy is performed. It most often occurs when animals are fed a high copper supplement designed for another species or too much copper has been added to a supplement. Abnormally high intake of
a supplement may also lead to problems.

Through the years I’ve had some cases where copper was deficient or tied up by other minerals. I hope these interest you.

A rancher grazing irrigated pastures kept his cattle in four groups of 150 head each. Each group was rotated through a separate group of pastures, so that each group had their own pastures. One of the groups never looked quite right. They really didn’t show off- color hair, but they never slicked off completely. The worming program on this ranch was based on continuous manure sampling and treatment. Flukes were not found in these cattle. The group in question weaned calves that were 50 lb lighter than the others. On two successive years, 2 calves suffered broken bones while they were being worked. No obvious injury was observed. While investigating the problem, we noticed that this particular herd had a small swampy area in it. We didn’t think the cattle spent much time there, and so discounted it as any part of the problem. We missed that one big time! We analyzed some grass out of the swamp and did a liver copper biopsy and found very high levels of molybdenum in the grass and virtually no copper in the liver. We immediately made a separate mineral with a high level of copper for this group, and what do you know, the weaning weights were up the very first year and the cattle were all slick and shiny. There were no broken bones after that.

Two brothers ranched on either side of a valley. Their cattle grazed in the hills as well as on the valley bottoms. We did forage testing and found that the forage on one side of the valley had high levels of iron and molybdenum and was very low in copper. On the other side of the valley, this was not the case. There was a moderately high level of iron and copper was marginally low. There was very little molybdenum. As it turned out, the fellow with a minor copper problem ran out of mineral and borrowed some of his brother’s mix. Within a week his cattle were all drawn up and looked horrible. While visitng him, I happened to ask if he was putting mineral out, or had been using a new mineral. He mentioned that he had run out of his mineral and just borrowed some of his brother’s. I was lucky enough to have the labels from both minerals and saw the huge difference in copper. One had 750 ppm while the other had 3500 ppm. My guess was that all the excess copper might have killed off many of the bugs in the paunch. The whole herd was run through the chute and given a probiotic to help re-establish the bugs and the mineral was changed back to his low copper mix. The cattle made a dramatic recovery and there were no further problems...there was no mineral sharing either!

Another fascinating copper event occurred on a ranch in Eastern Washington. The family purchased the ranch and their very first calving season was a total wreck. Many cows
didn’t breed. Their veterinarian and I both went to work. The vet checked for worms, flukes, and reproductive diseases. He also obtained liver, blood, and hair samples. We analyzed all of the different pastures. None of samples indicated that copper was a problem. The only thing that could be seen was some dead and off color hair. We decided to try supplementing copper even though there was nothing to support the idea that it was deficient. The following year the calf crop was back to normal, but the calves and the cows still showed some of the off-color hair. In the following years, we continued to increase the copper in the supplement, and each increase seemed to bring an improvement. Blood and liver samples showed no sign of toxicity. Repeated feed samples showed a decent level of copper in the grasses, with no unusual levels of iron, sulfur, or molybdenum. This reminded me of a statement made by Dr. Neville Suttle, the world’s foremost copper researcher. He stated that using the animal response was best, even when tissues and grasses didn’t indicate a problem.

The final case was presented at a copper symposium held in Seattle several years ago. Canadian researchers reported on cattle grazing grass on a reclaimed mining site. They reported that the feed had 40 – 100 ppm molybdenum and 15-18 ppm copper. (The highest molybdenum level in forage that I have seen is 5 ppm, and copper seems to range from 4-12 ppm in the Pacific Northwest). They saw no problems with calf growth or cow reproduction. They got no response to supplementing copper. When yearlings were grazed on land with similar copper and molybdenum concentrations, they saw normal gains, and no response to supplemental copper. This is absolutely contrary to what we would expect! Several ideas were presented to possibly explain this (1) the chemical form of the molydenum. (2) extremely high molybdenum may react differently in grazing cattle. I’d love to hear about your experience with grazing cattle on a reclaimed mining site.

Some observations mentioned at the copper symposium are quite relevant to our situation in the Pacific Northwest:

  1. There is no correlation between copper in the soil and in the plants.
  2. Cattle eating soil with a high copper content will affect the copper status of the animal.
  3. Sources of copper toxicity in addition to those mentioned earlier include drinking a copper sulfate footbath (mostly dairies), and pesticide ingestion.
  4. Swelling of the lower end of the leg bone or growth plate is a good indicator of copper deficiency.
  5. The copper in grazed grass is more poorly used by the animal than that found in hay, silage, and grain.
  6. Liming pastures adds to copper deficiency problems.
  7. Fescue pastures show unique copper problems! When performance is poor and no endophytes found, check copper status of cattle.
  8. Red Iron Oxide, which is used to give minerals and salt their ‘red color’ interferes with the availability of copper in the supplement.

After 36 years working with cattle minerals, apparently I still don’t understand copper (as well as many of the other nutrients!), and continue to find herds that are suffering production and reproduction problems that are related to copper. We now use more distillers grains than ever before. They are quite high in sulfur...much higher than book analysis tells us. Sulfur interferes with copper use by cattle, and this must be accounted for when using distillers grains as a source of energy and protein.

Michael J. Mehren, Ph.D. was last seen riding his copper-colored boar into the desert hoping to find desert truffles. He can be contacted by Email at

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