BOVINE KETOSIS AND SOMATOTROPIN - RISK-FACTORS FOR KETOSIS AND EFFECTS OF KETOSIS ON HEALTH AND PRODUCTION

Aspects of the metabolism and health of 63 cows which had been treated with different amounts of bovine somatotrophin (BST) daily in the pre ceding lactation and 25 control cows were studied. The aims of the stu dy were first, to identify cows with ketotic conditions, either by mea surements of blood metabolite concentrations or by clinical observatio ns, secondly, to evaluate the risk of such conditions in cows treated with BST in the preceding lactation, and thirdly, to examine the metab olic and production consequences of the ketotic conditions in an envir onment in which the cows' health, body condition and nutrition were cl osely observed. The cows were categorised objectively by the use of cl uster analysis into non-ketotic cows and ketonaemic cows, on the basis of their plasma metabolite concentrations. Twelve of the control cows and none of the cows previously treated with BST were classified as k etonaemic. Similarly, nine of the control cows but only two of the cow s previously treated with BST had clinical ketosis. Some, but not all, of the decrease in the risk of clinical ketosis was attributable to t he lower body condition score of the cows previously treated with BST. The clinically ketotic cows had a greater risk of other illness in th e first 10 days post partum than their herdmates, but the ketonaemic c ows had a significantly lower risk of other disease in the first 10 da ys post partum. The ketonaemic control cows were significantly heavier than the non-ketotic control cows, but they maintained a higher dry m atter intake than the latter cows, probably a key factor in reducing t he risk of clinical ketosis.