The need for copper and zinc supplementation in Montana

Part I

By John Paterson, MSU Extension Beef Specialist.

Q: Why should I be concerned about trace minerals for my cow herd?

Supplementing minerals to beef cattle has been shown to have positive effects on reproduction, immune status, disease resistance and feed intake. Trace minerals are needed 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. The requirement for trace minerals is often based upon the ability of the animal to maintain a desired level of performance. Table 1 shows the trace mineral requirements for growing and finishing cattle, and cows.

Table 1. Trace mineral requirements for beef cattle

Q: What are the symptoms of a copper or zinc deficiency?

Table 2 summarizes the potential effects of a copper and/or zinc deficiency in both cows and bulls. The main effects of copper and zinc deficiencies are a reduction in reproductive efficiency; delayed estrus, decreased conception rates and increased dystocia. In my opinion, I also believe that much of the footrot I see in Montana is related to trace mineral deficiencies because zinc and iodine supplementation appears to cure the problem.

Table 2. Symptoms of a copper or zinc deficiency in beef cattle

Q: Are there trace minerals that can reduce the utilization of copper and zinc?

Yes, it has been shown that an excess of sulfur, molybdenum and iron in the diet can interfere with the utilization of copper and may result in deficiency symptoms even though the levels of copper in the diet are adequate. This is one reason why nutritionists try to maintain a copper to molybdenum ratio of at least 4 to 1 when formulating diets or supplements.

The following table summarizes results of a survey conducted in Montana several years ago. This survey indicated that copper and zinc were deficient in most of the forages sampled (Table 3). Results with the grasses also indicated that there could be a secondary deficiency caused by a ratio of copper to molybdenum that was less than 4.

Table 3. Mineral Concentration of grasses, forage-mixes and legumes for Montana

Low forage levels of copper coupled with the antagonistic effects of molybdenum requires careful supplementation if you are experiencing any of the symptoms described in Table 2.

Q: What about sampling water?

The following figure shows the results of a ranch survey conducted in the northeastern part of the state. As a general rule, I start to worry about copper utilization when the amount of sulfate in the water exceeds 500 parts per million. This figure suggests that four of the ranches had sulfate levels higher than 500 ppm and trace mineral supplementation needs to be considered. Having livestock water analyzed can tell you much about the potential for causing health problems in your cowherd.

Figure 1. Sulfate concentration of water samples from northeast Montana ranches

Table 4 gives an example analysis of a water sample collected from a central Montana ranch.

Table 4. Livestock water quality recommendations and an example of a water sample from central Montana collected during Summer of 2002

The nitrate level was considered safe, but the sulfate level was at least eight times higher than recommended for cattle.

Q: What about sampling the liver to determine copper status?

The liver is probably the best organ in the body to give an indication of the copper status of the beef animal. The following table shows results from a survey of eight states conducted a couple of years ago.

Table 5. Percentage of cattle that were classified at deficient or adequate in liver copper 

What these results show is that in Montana, 61% of the cows sampled were considered to have an adequate amount of copper in the liver (>90 ppm) and less than 1% were considered to be severely deficient. The rest of the cows were between 30 and 90 ppm copper. One caution with these results, the cows sampled were from SW Montana and probably do not represent eastern Montana. Based on this survey, eastern Montana cows may have values more similar to western North Dakota and South Dakota. Cows from these two states appear to have a high percentage which would be considered deficient.

Take home message:

• Trace minerals can improve reproductive efficiency if cows are deficient.
• Many of the forages in Montana can be deficient in copper and zinc.
• Copper utilization is reduced with high levels of the antagonistic minerals molybdenum (in forage) and sulfate (in water).
• Liver biopsy results show that 62% of the cows sampled in Montana had adequate liver copper.

  Beef: Questions & Answers is a joint project between MSU Extension and the Montana Beef Council. This column informs producers about current consumer education, promotion and research projects funded through the $1 per head checkoff. For more information, contact the Montana Beef Council at (406) 442-5111 or at beefcncl@mt.net

Return to regular view	Text-only	Updated: 08/14/2009