Significant trace mineral deficiencies cause obvious clinical symptoms that are easily recognized. Unfortunately, most trace mineral deficiencies are marginal. Affected cattle suffer from subclinical disease and vague signs of not doing well.
Trace minerals are involved in innumerable chemical reactions throughout the body at the cellular level. While many of their functions have been identified, most remain a mystery.
The effect of trace minerals on immunity is the focus of a lot of current research. One of those studies was reported in The Bovine Practitioner.
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Copper has been shown to boost the action of infection-fighting white blood cells and affects antibody production. Zinc boosts antibody levels following vaccination. Similar claims are made for manganese and cobalt.
Based on this information, it was theorized that feedlot animals may be susceptible to infections because they are deficient in trace minerals on their arrival. If this is the case, supplementing calves while they are on pasture could conceivably boost their immunity. This in turn would lower the incidence of feedlot bovine respiratory disease.
To test this theory, cows and their calves were divided into three groups that were each given different mineral mixtures. All were offered a standard salt-dicalcium phosphate mixture. The control group received only this supplement.
A second group was given a metal-complex mineral, or MCM, which had added metal-complexed copper, manganese, zinc, and cobalt. The third group received inorganic minerals added as a sulfate base – sulfate-based mineral, or SBM.
To compensate for variations in availability, the SBM was offered at twice the concentration of the metal complex.
Vaccines were administered before weaning and again at weaning. The calves were weaned in early fall and shipped to the feedlot.
Liver biopsies and mineral analysis confirmed that supplementation boosted trace mineral levels in the calves. The MCM group had copper levels three times higher and the SBM group twice as high as the control group. Other mineral levels were also higher, although less dramatically, in the supplemented calves compared to the control calves.
Blood tests were done to assess individual responses to vaccination. Calves offered MCM or SBM had higher antibody levels against Pasteurella compared to the control calves. There was no significant difference
between the two types of supplement.
The calves on the metal-complex mineral supplement were better protected against disease. The number of “sick incidents” in the MCM-supplemented calves was half of that seen in both the SBM and control groups. There were no statistical differences between groups in terms of mortality.
Researchers concluded that improving mineral status before weaning through supplementation can reduce illness in the feedlot. Unfortunately, they didn’t
assess the economic feasibility.
If it is financially viable, producers will be able to provide calves that are less likely to get ill.
