Managing Mineral Deficiencies in Grazing Livestock ND Grace, SO Knowles and AR Sykes. Published in 2009 by New Zealand Society of Animal Production. 203 pp. ISBN: 978-1877257-93-3. Price: NZ$70.
The authors of this text, Neville Grace, Scott Knowles and Andrew Sykes, are to be congratulated for putting together a most useful manual Managing Mineral Deficiencies in Grazing Livestock. This is Occasional Publication No. 15 of the New Zealand Society of Animal Production, replacing Occasional Publication No. 9 on Mineral Requirements of Grazing Ruminants, which was published in 1983. This latest volume uses some of the subject headings from the previous publication, but expands greatly on the detail, along with updates.
Given the authors’ backgrounds, it is perhaps not surprising that New Zealand situations feature frequently in the text. The authors themselves point out (p. 26) that there is a need to validate overseas data for relevance to grazing livestock in New Zealand. Perhaps the need for validation also applies in reverse, given the many New Zealand-sourced publications cited. The text contains descriptions of mineral deficiencies and their remedies but, in spite of the title, there are also descriptions of the effects of excessive mineral intake (e.g. for manganese, selenium, zinc, chlorine, potassium, sodium and sulphurs).
Tables 1.1 to 1.3 at the beginning of the book provide useful summaries of reference material over all minerals for ruminants (mainly cattle and sheep). This section is then followed by a chapter for each mineral, although mention is made of interactions between minerals, such as iron and copper (p. 109), or interactions among groups of minerals, such as copper×molybdenum×ulphur (p. 64). Most chapters on the individual minerals contain subheadings for metabolism, function, requirements, signs of deficiency and recommendations for supplementation (or a summary of recommendations). Chapters 5–15 refer to the trace elements, followed by Chapters 16–22, which refer to the macro elements. This reviewer found it surprising that the chapters were not numbered, although the tables and figures are. Also, for those readers using this text as a reference manual, it might have been easier to be presented with one alphabetical list, instead of two.
Three other observations are that: it was most useful to be given the equivalence of mmol/l and mg/l units for all the concentrations mentioned; this reviewer found it helpful to have the repeated references listed again at the end of each chapter where cited; the glossary is a useful addition for the farmer or student and the appendix is useful for anyone needing a reminder about some basic chemistry.
The practical tips provided should be most useful to the farmer or student. For example, the authors point out that for magnesium supplementation to protect against hypomagnesaemia, administration through the water trough using magnesium chloride or sulphate with an in-line dispenser is a possible approach, but dairy cows are unlikely to drink enough water from the trough at relevant times, ‘since particularly during spring when the weather is cool, [they] will derive 90–120 l of water a day from pasture alone’ (p. 173). Another example, in the use of zinc for protecting ruminants against facial eczema: ‘do not give zinc sulphate as an oral drench because it can trigger a reflex action, causing the swallowed material to bypass the rumen’ (p. 145). Both are probably well-known points for the veterinary practitioner, but deserve to be mentioned when giving all the details for a wider readership, as in this text.
In conclusion, this book provides a useful reference text, consisting of an overview at the front of the book, followed by a series of chapters, one for each trace element or macro element.
Dr Chris A Morris
AgResearch, Ruakura Research Centre,
Hamilton, New Zealand
Email: [email protected]