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.

Trace Elements in Developing Countries Using South Africa as a Case Study

“…This study indicates vast areas of Se deficiency. A soil study was conducted, which agrees, to some extent, with the herbivore findings, although relationships are difficult to determine on the map scale (11,37). No studies on Se and HIV/AIDS in Africa have been conducted, (34) even though it has been shown to correlate well (13,34,35).…”

“…The chief biochemical function of Se is to serve as an essential cofactor to the enzyme "guluathione peroxidase" (GSHpx), and Se deficiency may be associated with myopathy, cardiomyopathy, and immune dysfunction (13,36). In South Africa, the importance of Se has been realized in the veterinary industry, and the Se status of herbivores has been determined (37). This study indicates vast areas of Se deficiency.…”

Selenium supplementation improves testicular characteristics and semen quality of Saanen bucks

“…This lack of Se confirms that the lucerne fed to the animals was Se deficient, as they had no access to pastures. This observation emphasizes the need for Se supplementation in regions such as Midlands and mountainous areas of the KwaZulu-Natal province, southern coastal region of the Western Cape where Se is deficient (van Ryssen, 2001) and also during winter times when animals are fed with lucerne that may be produced from this area and other areas that…”

Investigation of stillbirths, perinatal mortality and weakness in beef calves with low-selenium whole blood concentrations

“…Van Ryssen ( 2001 ) reviewed the selenium content of South African soils, but during personal discussions in November 2014, he stated that he has no data on selenium concentrations of soil in the Roossenekal area. The poor availability of selenium to plants is well illustrated by a study done to determine the selenium content of maize from South African silos.…”

“…It was hypothesised that a soil factor, most likely a lowering of the pH, reduced the bioavailability of selenium to vegetation (Courtman et al 2012 ). Soil-buffering capacity can be affected by acid rain and this could play an important role in limiting the bioavailability of selenium in affected areas (Davies & Mundalamo 2010 ; De Villiers & Mkwelo 2009 ; Van Ryssen 2001 ). The Roossenekal area is not far from active industrial areas and is also a site of mining activity.…”