MINERAL STATUS OF BORAN ZEBU CATTLE IN SEMIARID RANGELANDS OF SOUTHERN ETHIOPIA AND THE EFFECTS OF SUPPLEMENTARY PHOSPHORUS AND COPPER

A 12-month study was conducted in the southern rangelands of Ethiopia on the mineral status of Boran zebu cattle and their responses to supplementary P and Cu. The forages were marginal-to-deficient in Na, P and Cu (respectively 0.12 g kg-1, 1.6 mg kg-1 and 6.8 mg kg-1), probably due to the very low levels of these elements in the soil. Ca serum concentration at an average level of 5.1 mg (100 ml)-1 represented an acute hypocalcaemic condition, though it is not clearly understood whether this was a serious metabolic deviation in the breed or what consequences it could have. Supplementary P as bonemeal and injectable Cu had no remarkable effect on the serum mineral concentrations and condition of 2-3-year-old male cattle. Animals which received supplementary Cu but not P gained 10 kg bodyweight more than those which had neither supplement. No statistical differences were observed in blood mineral content due to physiological status. Consumption of saline waters apparently suppressed mineral supplement intake, resulting in daily consumption of 3 g P per head. The study showed that cattle supplementation with limiting mineral nutrients in pasture such as Na, P and Cu, under poor nutritional status, may be of no benefit unless limiting nutrients such as protein and low forage supply are rectified.