| Abstract: | In two experiments with 30 and 26 castrated male pigs of the German Landrace breed, weight range 15-30 kg, the influence of isoenergetic changes in the carbohydrate and fat fractions of the diet were examined. The effect of the addition of soya oil (SO) and lard (LA) to the diet on the utilization of protein and on the blood urea concentration was also examined. The apparent digestibilities of the crude nutrients and energy were determined using different methods. The following were examined: experiment I: ration I (control), ration II (+7% SO), ration III (+7% LA) experiment II: ration I (control), ration II (+2% SO), ration III (+2% SO + 5% LA), ration IV (+7% LA) In all experiments the animals were fed a similar amount of digestible crude protein of constant quality at constant ME-intake. In both experiments the apparent digestibility of crude protein in the groups with 7% added fat was 4% higher (p less than 0,05) than in the corresponding control groups. The apparent digestibility of crude fat in experiment I and II (in groups II and III and in groups III and IV, respectively) was approximately 87%, when calculated on the basis of faecal fat which was determined by a simple ether extract procedure. When the faeces was treated with HCl before determination, these values for experiment I and II were approximately 6% (p less than 0,001) and 1% (NS) lower, respectively. In both experiments the utilization of protein and the blood urea concentration were not significantly influenced by the amount or form of fat included in the rations. |
