USE OF PROLONGED-RELEASE BOVINE SOMATOTROPIN FOR MILK-PRODUCTION IN BRITISH FRIESIAN DAIRY-COWS .2. EFFECT ON HEALTH AND REPRODUCTION IN 2 CONSECUTIVE LACTATIONS OF TREATMENT

There were 45 cows in each of the control and treated groups in the first lactation of the study and, of these, 30 cows in each group received the same treatment for a second lactation. The study was conducted during the winters of 1985/86 and 1986/87. Injections of either bovine somatotropin (BST) or a placebo were started at day 60 ±3 post partum and repeated at fortnightly intervals for the remainder of each lactation. Body temperature and heart and respiration rates were unaffected by the administration of BST. Minor abnormalities were noted in individual animals in both groups, hygromata of the tarsus or carpus being most common. However, no health problems could be related to treatment. There was no evidence that the administration of BST increased the incidence of metabolic disorders. Ketosis was not observed in either lactation. © 1990, Cambridge University Press. All rights reserved.