Effect of Recombinant Bovine Somatotropin Injections on Deer Stag Plasma Insulin-like Growth Factor-I Profiles

This study was conducted to elucidate the influence of recombinant bovine somatotropin (rBST) on the plasma IGF-I profiles in deer stags. Slow release rBST (250mg each) preparations were injected subcutaneously during the antler's non-growing period and growing period. It was observed that significant increases in the plasma IGF-I concentrations were occurred right after injections of the rBST irrespective of antler's non-growing period or growing period. When the rBST preparations were injected two times with one week interval during the antler's non-growing period, the mean level of IGF-I was found to be 2,920.7ng I mL, indicating that the IGF-I concentration increased up to 8.4-folds compared with a control. After two weeks from second shot, however, the IGF-I levels decreased to the level of the control. Similar results were also obtained with both a Sika and a Red deer during the antler's growing period. Increases in the IGF-I level of up to 5.6-folds with the Sika deer and 4.3-folds with the Red deer were found. Based on the present study, it is likely that the rBST may be used as a possible candidate for an antler's growth stimulating agent.