[Glycerol as feed component and 14C-glycerol metabolism in rats]

Male Wistar rats (initial weight 58 g) received in four groups (10 animals per group) 0.0, 10.6, 21.3, and 31.8% glycerol in the dry matter of the diet (groups 1 to 4). The live weight gain of the animals was, after a feeding time of 3 weeks in the groups 1 to 4, 2.01, 2.49, 2.57, and 2.52 g, respectively, per animal and day. The higher gain in the glycerol groups resulted from the higher feed intake in these groups. Four rats per group received on the 22nd day of the experiment, 1 h after the morning meal, an intraperitoneal injection of carrier-free 14C-glycerol. The 14C-excretion in the respiration air and in the urine was measured in the following 10 h. The 14C-excretion in the 14CO2 of the respiration air was in % of the injected 14C-glycerol doses in the groups 1 to 4 = 45.4, 44.2, 39.0, and 33.2, respectively. The 14C-excretion in the urine was 17.0, 18.1, 25.1, and 32.3%, respectively. The higher values in groups 3 and 4 resulted from the high excretion of free glycerol in the urine. In groups 3 and 4 the glycerol content of the blood plasma was 1.9- and 1.5-fold higher than in groups 1 and 2. It was concluded that up to 40 mg glycerol per hour and animal (100 gLW) was metabolized in a physiological way in group 2. As a feeding component glycerol can constitute up to 10% of the diet-DM in monogastric animals.