Wood ash in livestock nutrition: 1. Factors affecting the mineral composition of wood ash

Author: J.B.J. van Ryssen & H. Ndlovu
Year: 2018
Issue: 1
Volume: 11
Page: 53 - 61

In resource-limited livestock production systems, the supplementing of mineral supplements is often not feasible because of economic constraints and possibly a lack of appropriate information. Wood ash is a pure mineral source that is usually readily available in many subsistence farming communities. As a starting point in evaluating its use in animal nutrition, factors affecting the mineral composition of wood ash are evaluated in this review. A survey on the composition of the wood ash from subtropical tree species in South Africa, and reports from many other countries, demonstrated that wood ash is primarily a calcium (Ca) source, though ash from a homestead fire may differ in composition if fire-making material other than wood is used. However, there is wide variation in Ca levels in wood ash compared to other Ca sources such as feed lime (CaCO3) and limestone. Furthermore, as is typical of most waste- and by-products the concentration of other elements, especially trace elements in wood ash, varies considerably, even within tree species. In this evaluation, factors that have a major influence on mineral composition in wood ash are tree species, tree components such as bark vs. wood ash, and also the temperature when burning wood. It is therefore concluded that because of the wide variation in the composition of wood ash, it is advisable to perform chemical analyses on ash available in a region before implementing feeding programmes. However, analysis for minerals is costly and will remain an obstacle in the sound application of ash in resource-limited areas. Furthermore, owing to the wide variation in mineral composition, it would be of little value to present the mineral composition of wood ash in feed composition tables. VanRyssen_vol 11_Issue_1_Wood ash in livestock nutrition 1 Factors affecting the mineral composition of wood ash

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