For Beef Cattle
This article appeared in the August 2001 issue ofthe "West Virginia Farm Bureau News, WVU Update."
Livestock Specialist
WVU Extension Service
The importance of mineral supplementation and nutrition isunderestimated by most beef producers, While subclinical deficiencies often gounrecognized, they cause a reduction in growth and efficiency and depress the immunesystem. Trace minerals are required for metabolism of nutrients, reproduction, immuneresponse, and nerve conduction. Deficiencies occur because cattle cannot consume enough ofthe minerals or because a dietary antagonist, such as sulfur or iron, is inhibiting theirutilization of a trace mineral.
The most deficient minerals in grazing cattle arephosphorus, copper, and zinc. In addition, West Virginia pastures typically are marginalto deficient in selenium. Cattle here should receive supplemental selenium because itplays a vital role in the reproductive and immune systems. The importance of phosphorousis well understood, but we are just beginning to understand the importance of copper andzinc.
These two minerals, when consumed in forages, do not seemto be highly available to the animal. Therefore, even if a forage analysis shows adequatelevels of copper and zinc, subclinical deficiencies can and do occur. For example, it isestimated that the absorption of copper from fescue by cattle is low, normally rangingfrom 5% to 15%. The importance of these minerals seems to be enhanced when cattle arestressed. There are indications that when cattle are stressed, the excretion of zinc fromthe body doubles and that of copper quadruples.
Weaned calves normally experience stress, which increasestheir susceptibility to infectious diseases. It is critical to provide adequate levels ofzinc and copper to calves at least 45 days before weaning and during weaning. Maintainingadequate levels of these minerals significantly reduces the number of deaths and improvesthe recovery rate of infectious bovine rhinotracheitis (IBR)-stressed cattle. IBR is aproblem throughout West Virginia.
The effectiveness of vaccines will be reduced if cattlehave a subclinical deficiency of these trace minerals. In addition, wormy cattle have lessability to build an adequate immune system, even when effective vaccines are being usedsystematically. Examine the tag on your mineral supplement and look for copper sulfate andzinc oxide or zinc sulfate because these are highly available to the animal. At a minimum,it appears that when minerals are consumed at a level of 2 ounces per head per day, themineral should contain at least 1,000 ppm copper and 2,500 ppm zinc.
If your calves experience pinkeye, watery eyes, foot rot,or respiratory problems, you should examine your mineral supplementation program.