EFFECT OF DIFFERENT SOURCES OF DIETARY FI BER ON NUTRIENT AND ENERGY-UTILIZATION IN BROILERS .2. ENERGY AND N-BALANCE AS WELL AS WHOLE-BODYCOMPOSITION

Various sources of dietary fibre (millet and soybean hulls) as well as wheat starch were investigated for their influence on nutrient and en ergy utilization in broilers. Twenty percent of the control diet (KO) were either replaced with wheat starch (20% STA), millet hulls (20% HI ) or soybean hulls (20% SO). In two consecutive series of experiments, the experimental diets were led ad libitum to 192 male chickens of Ro ss hybrid (8 birds per cage) from day 8 to day 42. At the end of the t rial, whole body composition was determined. Due to the highest energy losses by excreta and a slightly increased heat production, the lowes t energy balance (529 kJ/kg LW(3/4)) was seen with diet 20% SO. Higher energy balances resulted with diet 20% STA (631 kJ/kg LW(3/4)) und 20 % HI (642 kJ/kg LW(3/4)). Values from 0.654 to 0.726 were estimated fo r the transformation of metabolizable energy into retained energy. The high energy balance of diet 20% HI could be due to interactions betwe en the indicator content of the diet (HCl-insoluble ash) and the high silicium content of millet hulls. This could also be observed in N uti lization. N intake depended on feed intake and the crude protein conte nt of the diet. In comparison to the control, N losses by excreta of 2 0% SO birds were increased br 30%. Addition of hulls led to an improve d N-balance 5-9%). In all diets, highest N-balances per kg LW(3/4) res ulted in week 3 and decreased up to week 6. Large variations occured i n ht retention. No fibre related influence could be seen in nutrient c ontent of whale bodies. Wheat starch addition mas followed br an incre ase in fat (7%) and energy (5%) content, whereas the other nutrients w ere diluted. Nutrient composition of the whole body depended significa ntly on the energy:protein ratio of the diet. In comparison to whole b ody composition, N and energy deposition were overestimated by the bal ance method by about 20%.