Cobalt Deficiency Effects on Trace Elements, Hormones and Enzymes Involved in Energy Metabolism of Cattle
1999
Stangl, G. I. | Schwarz, F. J. | Kirchgessner, M.
This study was conducted to investigate the physiological consequences of long-term moderate cobalt deficiency in beef cattle, which have not hitherto been studied in detail. Cobalt deficiency was induced in cattle by feeding two groups of animals either a basal corn silage-based diet that was moderately low in cobalt (83 mug Co/kg), or the same diet supplemented with cobalt to a total of 200 mug per kg, for 43 weeks. Cobalt deficiency was induced, as judged by inappetance, diminished growth gain and a markedly reduced vitamin B<sub>12</sub> status in serum and liver. The long-term cobalt deprivation which was primarily a combination of reduced feed intake and a tissue vitamin B<sub>12</sub> deficiency did not show evidence of a significant dysfunktion of energy metabolism. The activities of glucose-6-phosphate dehydrogenase and cytochrome oxidase in liver remained unaffected by cobalt deficiency, nor was there a significant change in serum glucose level of cattle on the cobalt-deprived diet. However, analysis of thyroid hormone status indicated a slight reduction of type I thyroxine monodeiodinase activity in liver accompanied by a significant reduction of the triiodothyronine level in serum. The diminished liver vitamin B<sub>12</sub> level resulted in significantly reduced folate level in this tissue, reduced concentrations of heme-depending blood parameters. Moreover cobalt deficiency or rather vitamin B<sub>12</sub> deficiency was accompanied by a dramatic accumulation of the trace elements iron and nickel in liver. These results indicate that long-term moderate cobalt deficiency may induce a number of physiological changes in cattle, but a follow-up study, which excluded different feed levels by including a pair-fed control group, will be necessary to actually obtain the single effect of cobalt deficiency in cattle.
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