According to a 4×4 Latin square design, four adult ovariectomised sows fed at a similar energy level (516 kJ ME/kg body weight (BW)0·75 per d) received one of four diets successively: a control low-dietary-fibre (DF) diet (diet C, 100 g total DF/kg DM) and three fibre-rich diets (200 g total DF/kg DM) that corresponded to a combination of diet C and maize bran (diet MB), wheat bran (diet WB), or sugar-beet pulp (diet SBP). Sows were adapted to the diet for 12 d before an 8 d measurement period. Digestibility of energy and nutrients in the diets, and total heat production (HP) and its components (fasting HP, activity HP and thermic effect of feeding (TEF), were measured. The TEF was partitioned between a short-term component (TEFst) and a long-term component (TEFlt). Total tract digestibility of nutrients and energy was greater for diet C; among the three other diets, the digestibility coefficients were higher for diet SBP than for diets MB and WB. Energy losses from CH4 were linearly related to the digestible total DF intake (+1·4 kJ/g). Fasting HP at zero activity averaged 260 kJ/kg BW0·75 per d. Activity HP represented 20 % total HP, or 83 kJ/kg BW0·75 per d on average. Total TEF and TEFlt were higher (P<0·05) for diet WB than for the other diets. However, total HP (406 kJ/kg BW0·75 per d) was not significantly affected by diet characteristics. Our results suggest that metabolic utilisation of dietary energy is little affected by the addition and origin of DF, at least under the conditions of the present study.
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