Development of a system classifying and monitoring the availability of minerals to cattle in the ranching areas of SWA/Namibia

Abstract

Abstract taken from Dissertation Abstracts International, vol 51, no 6, December 1990, p. 2684-B:

A survey was undertaken to determine the availability of various mineral elements to cattle, in the grazing of the cattle ranching areas of SWA/Namibia. For this purpose large numbers of liver and faecal samples from a large number of cattle were analysed. From the results thus obtained, a classification system was developed to classify areas of possible mineral deficiencies according to different vegetation, soil type and geological zones. To monitor all important trace minerals in one program, an ecological classification system, taking vegetation, soil type and geology into account, would be the best to select areas of possible and deficiencies. If specific minerals are to be monitored, more specific classification systems should be used, to improve the selection of potentially deficient areas. For the monitoring of copper, a detailed soil classification system would be the best indicator of possible deficient areas. A geological classification would be the best to select areas for the monitoring of iron deficiencies, while classification according to relative homogeneous production areas will be most effective in selecting areas of possible manganese and cobalt deficiencies

Although these classification systems can be used to isolate areas of relative mineral deficiency, no actual deficiencies of copper, iron, zinc, magnesium or manganese were found. There were some indications of selenium deficiencies, especially in the northern part of the country. This mineral should receive further attention in monitoring programs. Phosphorus and iodine deficiencies were found in large areas of the country, and these minerals should thus be monitored on a more regular and intensive basis

Phosphorus concentration in a faecal sample from a representative group of animals was found to be a reliable and practical indicator of the phosphorous status of the herd. The phosphorus and nitrogen concentration in faeces also reflected the quality of the grazing consumed fairly accurately. Phosphorus concentration in faeces did, however, not reflect the phosphorus intake from lick supplements. This was due to the interaction of phosphorus with other nutrients such as protein. This is also the reason why it is recommended to do nitrogen and calcium determinations in combination with phosphorus determinations in faecal samples