Abstract
The purpose of the present study was to examine the responses of plasma growth hormone (GH) and insulin-like growth factor-I (IGF-I) levels to intravenous injection of xylazine in female dairy calves. Xylazine (0.05, 0.15 and 0.30mg/kg body wt., iv) injections induced a significant dose-dependent increase in plasma GH level within 30min. After plasma GH levels reached peaks, GH concentrations began to decrease immediately and they returned to control levels 1h after xylazine injection. Plasma IGF-I concentration tended to be suppressed by xylazine treatment. Xylazine induced a significant dose-dependent increase in plasma glucose for 3.5 to 5.5h after the treatments. Xylazine also induced a significant decrease in plasma insulin level within 30min after treatments. The present data suggested that xylazine stimulates GH release in cattle.
