Energetic utilization of dietary fiber in pigs

The energetic utilization of fermentable dietary fiber (fDF) of different fiber sources and its relation to physical activity and housing conditions was studied in three experiments. In all experiments the daily intake of digestible nutrients, nitrogen and energy balances, heat production, and activity-related heat production was measured in climatically controlled respiration chambers. The energetic utilization of fDF was estimated from the linear relationship between heat production and the intake of fDF, after correcting heat production data for other nutrients and methane production. It was found that the energetic utilization of fDF from sugar beet pulp silage (SBPS) was 14.7 kJ/g in group-housed sows. This was slightly higher than for group-housed growing pigs (14.1 kJ/g). The relatively high energetic utilization of fDF from SBPS was related to the decreased activity-related heat production (AHP) with fDF intake. In group-housed growing pigs, the energetic utilization of fDF from solvent-extracted coconut meal and soybean hulls was similar; on average 10.6 kJ/g. There was no relationship between the intake of fDF and AHP. Increased dietary bulkiness and fermentation in the gastrointestinal tract increased the empty weight of the gastrointestinal tract by increased empty weights of the stomach and large intestine, respectively. Digestibility and metabolizability of dietary energy was higher for individually housed growing pigs than for group-housed growing pigs. The energetic utilization of fDF was only numerically higher for individually housed pigs than for group-housed pigs. Individually housed pigs were able to decrease their AHP with the same magnitude as group-housed pigs. It was concluded that there are differences in the energetic utilization of fDF from different origin. Differences in energy expenditure on physical activity play an important role. The rate of fermentation may be of importance. Possible mechanism should be further investigated.