EFFECT OF MILLET AND SOYBEAN HULLS ON NUT RIENT AND ENERGY-UTILIZATION IN GROWING PIGS .2. ENERGY AND N-BALANCE

An experiment with growing pigs was conducted to examine the effects o f various sources of dietary fibre in comparison to starch on growth p erformance and energy utilization. Twenty percent of a control diet (K O) were either replaced with wheat starch (20%STA), miller hulls (20%H I) or soybean hulls (20%SO). Sixteen male Large White castrates were h oused in individual pens from 20.0 +/- 2.5 kg live weight (LW). The an imals were restrictively fed a pelleted diet. After having reached 36. 1 +/- 3.2 kg LW, faeces and urine were collected and calorimetric meas urements were performed for 8 weeks. Because of the restricted feeding , intake of gross energy did not depend on the diet. Addition of wheat starch was followed by lower energy losses through faeces (-15%), whe reas corresponding values were increased in diets 20%SO and 20%HI by 1 2 and 63%, respectively. No dietary influence was determined either by energy losses in urine and methane or by heat production. Differences in energy balance (average: 562 kJ/kg LW(3/4)+day) between the diets were therefore mainly determined by faecal losses. According to the da ily feed consumption and the dietary protein content, the highest N in takes were observed for 20%SO- and KO-pigs and the lowest in diets 20% STA and 20%HI, respectively. Millet and soybean hull addition increase d faecal N excretion by 38 and 10%, respectively. In comparison to the other diets, urinary N output was enlarged by 20% in diet KO. N-balan ce and protein retention of 20%HI-pigs were decreased by 11%, whereas no significant differences could be determined among the other diets ( average: 1.08 g N/kg LW(3/4)+day). In comparison to diet KO, fat reten tion of 20%STA animals was increased by 14%, whereas millet hull addit ion led to lower fat retention (-36%). It can be concluded that differ ences in fibre utilization were mainly influenced by the processes in the digestive tract and less by the ones in the intermediary metabolis m.