Abstract

Where mineral deficiencies have characteristics clinical signs (eg. milk fever or hypocalcaemia) or necropsy findings (eg. white muscle disease) diagnosis is comparatively easy. However, many mineral deficiencies are characterised by poor growth or production which are non-specific signs that can be caused by many factors. In these instances a systematic approach is required to determine if a mineral deficiency is likely to be involved. This paper outlines such an approach which includes: Description of animal health problem including a comparison with target weights and production parameters. Deduction of likely causes using clinical signs, soil, climate, plant and management clues. Diagnosis using appropriate diagnostic tests. The best tests are animal response trials or analysis of animal tissue parameter levels which can be related to a production response. Choice and results of animal diagnostic tests must be considered in relation to what the sampled tissue represents (eg. mineral intake, storage site or where the element functions), and the limitations placed on the test by other factors (eg. effect of concurrent disease). The importance of sufficient sample numbers to reflect herd mineral status and selection of animals for sampling in a random manner is emphasised. Interpretation of results and advice should be based on epidemiological knowledge of the mineral deficiency and the economic benefits of mineral supplementation. The use of animal diagnostic tests to predict some mineral deficiencies (preventive medicine), especially in areas of marginal deficiency, is briefly discussed. Because of the complexity of some mineral deficiency problems a team approach involving farmer, agricultural adviser and veterinarian is recommended.

IS, Cornforth

Proceedings of the New Zealand Society of Animal Production, Volume 44, , 135-138, 1984