[Glycerol as a feed component in fattening pigs]

The production of motor fuel from rapeseed oil forms large amounts of glycerol as a waste product (about 100 g per kg oil). The aim of this experiment was to test glycerol as a component in diets of fattening pigs. In two experiments received 48 pigs (Pietrain x F1, Landrace x German breed) up to 30% glycerol in barley-soya bean oil meal diets. Six pigs per group with an initial weight of 32 kg (experiment 1) and 31.2 kg (experiment 2) in average received the diets semi ad libitum during the whole fattening periods. Barley was replaced by glycerol, that the content of glycerol in diets amounted 5 and 10% (1st exp.) and 5; 10; 20 and 30% in the 2nd exp. respectively. The feed intake was in order of groups up to slaughtering in exp. 1: 1.98; 2.17 and 2.23 kg DM/animal and day and in exp. 2 over 71 days: 2.26; 2.44; 2.54; 2.32 and 2.37 kg DM/animal and day. The sweet taste and the better feed structure of diets with glycerol supplementation is the reason for the higher feed intake in the groups with a glycerol supplement. The daily live weight gain was in the same order 631; 719; 754; 731; 770; 819; 704 and 598 g/animal resp. The feed conversion ratio was only in the group with 30% glycerol significant different from all other groups (3.96 against 2.95-3.30 kg DM/kg live weight gain). 30 min. after feeding the glycerol concentration in blood rose evident with higher glycerol content in diets. It was also found a higher glycerol content in the urine in dependence on the glycerol concentration in the blood. Glycerol in diets changed not the carcass yield and the meat quality. Pathological changes of liver and kidney of animals were not found after glycerol feeding. Amounts of glycerol up to 10% in the diet are recommended.