Ruminant thiamine requirement in perspective.

Thiaminases play an important role in the aetiology of CCN being responsible for the state of thiamine-deficiency which is an essential feature of the disease, evidence for which is presented here. These studies have led to a greater appreciation of the role of thiamine and thiaminases in ruminant nutrition especially as ruminal thiaminase activity is not confined to clinically affected animals but is of wider distribution. The importance of thiaminases in intensive beef production and the possibility of the need for thiamine supplementation in the form of a thiaminase resistant derivative is discussed.