Cobalt

Cobalt's importance is entirely as an essential component of vitamin B12, formed by rumen organisms and absorbed, with the aid of gastric intrinsic factor, from the ileum.

Functions

The prime functions of vitamin B12 in ruminants are in energy utilisation from propionic acid and in haemopoiesis. There are other functions relating to lipid, carbohydrate and nucleic acid metabolism.

Effects

Anorexia, lethargy, poor growth, wasting, anaemia (normocytic, normochromic). This may be in the presence of ample feed - starving amid plenty.

Occurrence

Cobalt deficiency in sheep is common and well recognised in many countries. Less is known about the situation in cattle. As with iodine, this is partly because of an analytical problem (see below) but nevertheless, cattle Co problems are commonly recognised in Australia, New Zealand and elsewhere. In Ireland, at least 55% of cattle in 680 herds examined were low in B12.

Soils where cobalt deficiency may occur range from granite to sand in origin, and so the geological background is not helpful. Also, pasture factors are important, just as for the other trace elements. Since mapping is futile, cobalt deficiency should be considered as a possible cause in any problem of inappetance or poor growth in grazing ruminants.

Diagnosis

Most early diagnoses were based on weight gain trials.

There is a problem in B12 analysis in cattle (but not in sheep) because of binding to a protein. Results are therefore unreliable. Methyl malonic acid is assayed by some laboratories. This increases if B12 is inadequate, and so can be useful in identifying deficiency. Dr. Lee McDowell (Gainesville) uses liver cobalt estimation, and finds it meaningful, but I do not know of other US labs doing this test. Unfortunately, the multi-element liver biopsy testing done at Michigan State University by Dr. Braselton and others is insufficiently sensitive for cobalt or selenium estimations, and is inappropriate for iodine.

Control

Control Published requirements (NRC) are 0.07 - 0.11 mg/kg of dry matter intake. As for other trace elements, in-feed supplementation is easy, and free access is extremely difficult. Persistence of a single oral drench dose of cobalt is only 1 to 2 weeks, and B12 injections would be too expensive and short-lived for herd use.

Tracesure Cattle/Calf and Tracesure Sheep/Lamb boluses, provide selenium and cobalt by slow release for 5 - 6 months.

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