Effect of rbST and calcium soaps on the performance of lactating dairy cows

The aim of this study was to determine the responses of lactating cows to bovine somatotropin (GH) and supplementary dietary calcium salts of long-chain fatty acids (Ca-LCFA). 80 Friesian cows (approx. 119 days post partum) were randomly assigned to 1 of 4 treatments: (1) control diet (C); (2) 0.5 kg/day added Ca-LCFA (Ca-LCFA); (3) control diet + GH (GH); (4) 0.5 kg/day added Ca-LCFA + GH (Ca-LCFA + GH). GH, 640 mg/injection, was administered in a sustained-release vehicle at 28-day intervals for 84 days. At 7 days post-injection, GH decreased milk urea content ( P<0.01) and increased the proportion of long-chain fatty acids in milk fat ( P<0.05).