Geographical distribution of the selenium status of herbivores in South Africa

Abstract

Available information on the selenium (Se) status of grazing herbivores in South Africa is reviewed and collated in the form of a geographical distribution map. Marginal to acute Se deficiencies have been reported to occur in the Midlands region and in mountainous areas of the KwaZulu-Natal province and in the southern coastal region of the Western Cape province. These areas receive a high annual rainfall and the soils are predominantly acid. The Se status of livestock in the highland sourveld areas of the Gauteng, northern Free State and Mpumalanga provinces is varied. Selenium intake appears to be adequate in most areas although localised cases of deficiencies occur. Substantial air and water pollution occurs in some of these areas, and the presence of Se antagonists could increase the incidence of Se deficiency in future. Limited data indicates that vegetation in the arid regions of South Africa provides Se sufficient to meet the requirements of grazing herbivores. Subterranean water from a number of locations contains Se at concentrations higher than the norm for safe drinking water, the impact of which has not yet been established. There are large areas of South Africa for which little or no information on the Se status of grazing animals exist, and further investigations are required.