Cobalt deficiency of cattle grazing improved pastures in northern Cape York Peninsula

Abstract

Trace element deficiencies were suspected in cattle in an area of Cape York Peninsula that receives a predominantly summer rainfall of more than 1500 mm and has soils low in nutrient concentration. Consequently cattle were treated with cobalt and copper while grazing Panicum maximum-Stylosanthes guyanensis pastures. After 11 months the fiveweight gains for the four treatment groups were : nil -21 kg ; +Cu -2 kg; +Co +142 kg and +Cu + Co + 121 kg. Many of the animals not given cobalt were emaciated and near death at that time. A group of these animals gained 79 kg in 50 days after receiving supplementary cobalt. Blood copper levels were not affected by treatment but treatment with cobalt decreased blood urea-nitrogen values in the dry season. Cobalt treatment also increased serum vitamin BIZ levels 3-4 fold, increased the liver vitamin B12 levels 10-20 fold and enhanced the storage of copper in the liver. Apart from a short period early in the wet season, the pastures contained less than 0.025 ¦g Co g-1 dry matter. These levels are discussed in relation to the dietary requirements of grazing cattle.