Recent Advances in Copper and Selenium Supplementation of Grazing Ruminants

Procedures for providing supplementary copper and selenium were classified into methods which involve direct application to pasture, free access methods, drenches, parenteral injections and slow release techniques; the advantages and disadvantages of each are examined with emphasis on procedures which have recently become available. A major problem is the subclinical deficiency which is often transient and difficult to identify but has a significant effect on productivity; alleviation can often be achieved at low cost once the problem is identified giving a favourable cost-benefit relationship.