GLYCEROL SUPPLEMENTATION TO BROILER RATIO NS WITH LOW CRUDE PROTEIN-CONTENT

In connection with the utilization of glycerol, which could become ava ilable as a by-product of the fuel production from rapeseed the influe nce of glycerol feeding with rations of low crude protein content was proved. 61 male day old broiler chickens received ad libitum 8 experim ental rations based on maize and soybean meal. The experimental design included 3 factors: 15 or 18 % CP; supplementation of essential amino acids or not and a content of pure glycerol of 0 or 10 %. During the experimental feeding of 23 days body weight gain, feed convertion rati o, N-balance and the intake and excretion of glycerol was obtained. Al the end of the trial the utilization of N-15-methionine and the glyce rol content of blood plasma, liver and breast muscle was estimated. Du e to the low crude protein content of the rations the body weight gain and N-balance was very low (BWG day 1 to 23: 8.6 to 17 g/animal.d; N- balance day 19 to 23: 0.4 to 1.0 S N/animal.d). The supplementation of essential amino acids was the factor with the highest improving effec t on the body weight gain, feed conversion ratio and N-balance. Especi ally at the begin of the trial animals which received 10 % glycerol ha d have an increased feed intake. The excretion of the supplemented gly cerol by excreta amounted to 26 % of the intake. However, the glycerol content of the rations did not effect body weight gain, feed conversi on ratio, N-balance or utilization of N-15-methionine significantly. T he assumption of a saving effect on glucoplastic amino acids due to gl ycerol feeding could not be manifested. In the mean feeding of glycero l elevated the glycerol level in blood plasma in comparison to the bas al level up to 23 times (from 0.6 to 13.6 mu mol/ml) and in the breast muscle up to 19 times (from 0.4 to 7.5 mu mol/g). Nevertheless, these values were lower than the basal level of glycerol in the liver (17.1 to 19.0 mu mol/g), which was significantly increased by glycerol feed ing to 128 %. Regarding the utilization of glycerol as a by-product of the production of renewable fuels it can be concluded that on the bas is of the estimated parameters 10 % pure glycerol in broiler rations i nsteed of corn starch is without adverse effects.