The Influence of Mineral Deficiencies on Genetic Improvement Programs

Deficiencies of phosphorus, copper, cobalt and selenium are the main mineral deficiencies in southeastern Australia that are likely to affect lactation, growth, carcass composition and wool production of grazing livestock being compared in genetic improvement programs. Genetic variation in mineral nutrition has been recognized from differences in the incidence of mineral disorders between breeds. The development of diagnostic indicators for measurement of minerals or their associated enzymes in blood, other fluids and tissues, has led to the recognition of genetic variation in mineral metabolism. The heritability for some indicators such as plasma copper is estimated to be as high as 0.4. The opportunities, practical difficulties, and likely benefits from considering genetic variation in mineral metabolism in genetic improvement programs are reviewed. It is concluded that there is an opportunity to select animals on the basis of genetic variation in metabolism of some trace elements, but the regional and sporadic nature of mineral deficiencies in Australia and the acceptance of supplementation by producers is likely to result in slow progress.