Effect of recombinant bovine somatotropin (BST) on physiological parameters and on milk production in German...

The efficacy of injecting primiparous cows of a dual purpose breed (Deutsches Fleckvieh) with a BST prolonged release formulation (500 mg Sometribove s.c.) was tested in a cross-over design. Seven cows were given 500 mg BST in the 10th through 19th week of lactation and a placebo in the 24th through 33rd week. A second group of seven cows received a placebo in the 10th through 19th week and BST in the 24th through 33rd week. Blood samples were taken from the jugular vein (via a permanent cannula) in the 13th, 17th, 23rd, 27th and 31st week of lactation over a period of 24 hrs at 30 min intervals. During the periods of BST treatment the amount of FCM (amount of milk corrected to 4% fat content) was higher in treated than in non-treated animals by 3.6 kg (19.8%) and 3.2 kg (22.5%) respectively. Milk fat levels were elevated significantly during both treatment periods. Milk protein concentration showed a significant rise during the second half of lactation only. There was no influence on lactose content. Blood concentration of somatotropin and IGF-I rose during treatment by a factor of 3-4. Insulin, T3, T4 and FTI as well as glucose, urea and GOT showed no changes or changes within physiological ranges. Free fatty acids and beta-hydroxybutyrate rose during treatment.