BODY AND FAT TAIL GROWTH AND CARCASS RESPONSES TO CLONIDINE IN KARAKUL RAM LAMBS

Karakul fat-tailed lambs were used to study growth and fattening effec t of the alpha(2)-adrenergic agonist clonidine. Body weight, feed inta ke and fat tail size (volume, length and circumference) were measured weekly in ram lambs beginning at 9 wk of age when lambs were treated w ith saline (n=4) or clonidine (n=5, 20 mu g/kg/min) for three consecut ive 28-d periods. Saline and clonidine were administered using 28-d Al zet(R) osmotic pumps surgically implanted under the shoulder skin. Bod y weight gain (BWG) and tail volume gain (TVG) were elevated (P<0.05) in period 2 relative to periods 1 or 3. However, the TVG/BWG ratio inc reased (P<0.05) in period 2 and remained elevated in period 3. Thus, t he TVG measurement reflected the increased tendency to fatten with adv ancing age. Clonidine had no effect on BWG or TVG. Tail circumference gain (TCG) and TCG/BWG tended (P<0.16) to be depressed by clonidine in period 1 (P<0.16) which suggests that a tolerance to clonidine may ha ve developed.