Abstract
In the ruminant, hypothyroidism is the commonest type of thyroid disorder encountered. Hypothyroidism in ruminants may cause serious losses in both production and reproduction, especially on intensive grazing systems and in endemic goiter areas where soil I content is low. The need for further research is apparent, both in the realms of mapping the soil I content and its uptake by herbage in different areas, and in the development of other diagnostic tools such as the determination of blood free and bound thyroxine.