Basis of Copper Deficiency in Cattle Better Understood

REGINA - Mar 22.04 - SNS -- Researchers are gaining a better understanding of why copper deficiency develops in some cattle as part of a series of projects supported by the Agriculture Development Fund (ADF).

The latest was called "Chemical Studies of Organic Trace Metal Supplements" and carried out by a team of researchers in the Department of Chemistry, University of Saskatchewan, which was headed by associate professor Dr. Steve Reid.

Copper deficiency in cows occurs in some areas of Saskatchewan because of significant levels of sulphur in ground water and trace levels of molybdenum in feed, explains Reid. Sulphur is common in Saskatchewan's ground water, but molybdenum, while only present at trace levels in the soil, may accumulate to significant levels in forages.

"When these chemicals combine in the cow's rumen, thiomolybdates - which we refer to as 'TMs' - can be formed. And these TMs strongly bind copper to form an insoluble product that renders copper unavailable to the animal, even though it is present in the diet. The result is a secondary deficiency of copper," says Reid.

A previous ADF project had established the importance of copper binding with amino acids and small groups of bonded amino acids called "peptides." The researchers also established that a particular class of peptides might confer protection against the TMs. Modern copper dietary supplements, in fact, are often combined with peptides.

"For these reasons, we developed a more sophisticated computer simulation of the amounts of different chemical forms of copper in the bovine rumen, including a copper-peptide species. This model, combined with insights from previous studies, will allow us to predict probable protectants against secondary copper deficiency.

"This study focussed on the rumen, where we identified some molecules that will halt the binding process while it is still at the soluble stage. We found we can model where the copper goes in healthy cows, so now we can incorporate the TMs into that and test them in a comprehensive computer model.

"We still don't know all the details of the chemistry but we do know more than we did before. This project represents a significant advance in our ability to tackle the problem of copper deficiency in cows, and allows us to move forward with our current project," says Reid.

A copy of the ADF project "Chemical Studies of Organic Trace Metal Supplements," ##035; 20000283, may be obtained by phoning 306-787-5929 in Regina. The final report is also available on the Saskatchewan Agriculture, Food and Rural Revitalization Web site.

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