Mineral and trace element research in goats: A review

The long term studies with dairy goats on the effects of deficient semisynthetic feeding rations in one of 16 elements as reported in the annual proceedings of the Workshops on Minerals and Trace Elements and the International Trace Element Symposia by the University of Jena, Germany, since 1975 until today were reviewed. The development of the complex semisynthetic ration system was particularly important as it enabled to produce significant deficiencies of single elements in long term replicated studies and their interactions with other elements. The studies focused mainly on determining deficiency levels for each of the 16 elements, identifying deficiency symptoms and reasons for them, and establishing evidence for essentiality of the elements according to 7 criteria. Large amounts of analytical data were accumulated showing the changes in organ and tissue contents of the elements under study at normal and deficient levels, and their relation to impaired reproductive efficiency, growth, milk production, health, and mortality of goats and their kids. Histological sections of organs also showed their ultrastructural changes due to the elemental deficiencies. Most element deficiencies caused reproductive failures, reduced growth and milk production, but high mortality, while the control goats thrived on their semisynthetic but sufficient ration, attesting to its completely correct biological value. The identification of the reliable “indicator” organs and tissues for the diagnosis and detection of deficiency status of the specific elements in goats is of particular value to veterinary medicine and animal nutrition.