Glucose Homeostasis Differed in the Fast- and Slow- Growing Chickens (Gallus domestics)

To evaluate the genotypic effect on glucose homeostasis in chickens, we conducted the oral glucose tolerance test, and insulin sensitively test (OGTT and IST) in the fast- (FG) and slow- (SG) growing broilers. Each of 120 one-day-old males was raised in 10 batteries, respectively. In the OGTT test, ten broilers on d 42 fasted 12 h from each stock were randomly assigned into two groups: glucose and vehicle, respectively. The glucose group received a glucose syrup by oral gavage (2 g/kg BW), while the vehicle group received an equivalent volume of normal saline. In the IST test, twelve chickens on d 70 fasted 12 h from each stock were assigned into four groups, respectively. Each of 3 birds was injected with human insulin at the dosage of 40, 60, and 80 mu g/kg BW via intraperitoneal injection, respectively. In both trials, the blood glucose concentration was determined at 0, 10, 20, 40, 60, 120, and 180 min through small brachial blood vessels. As a result, the blood glucose of both group was increased immediately after being treated with glucose and reached peaks at 20 min, then recovered to the normal at 60 min. Birds treated with glucose had greater blood glucose concentration and area under the curve (AUC) in SG than those of FG (P> 0.05). Administration of insulin at 40 and 60 mu g/kg BW dramatically decreased blood glucose level in FG but didn't affect SG. And at 40 mu g/kg BW insulin administration, FG had lower blood glucose than SG (P < 0.05). These results suggested that the growth speed greatly affects oral glucose tolerance and hypoglycemic response to exogenous insulin in chickens.