Effect of Dietary Fibre on Digestibility and Energy Metabolism in Pregnant Sows

A novel Bacillus sp. with rapid growth property and high enzyme activity that allows efficient fermentation of soybean meal for improving digestibility in growing pigs

AIMS

Soybean meal (SBM) contributes high-quality dietary protein for pigs. However, it also contains antinutritional factors such as allergenic high molecular weight proteins and non-starch polysaccharides (NSP) that limit its use. Therefore, the objective of this study was to screen and characterize a robust Bacillus sp. from camel dung for soybean meal fermentation to improve the digestibility in growing pigs.

METHODS AND RESULTS

Molecular characterization revealed that isolate 9 (hereinafter referred to as "CP-9") was a Bacillus subtilis strain. It secreted cellulase (0.07 U ml-1 ), xylanase (1.91 U ml-1 ), and amylase (2.66 U ml-1 ) into the culture supernatant. Isolate CP-9 showed rapid growth on LB agar plates and grew at a wide range of pH (3.0-9.0) and temperatures (23-50°C) in LB broth. Protein profiling of SBM using SDS-PAGE showed a significant reduction of large globular proteins to small peptides after 48 h of fermentation. On a dry matter basis, neutral detergent fibre (NDF) of the fermented SBM (F-SBM) was decreased by 34.25% (from 9.72 to 7.24%) with an increase in CP content by 16.54% (from 48.74 to 56.80%). Pigs fed with a semi-purified diet formulated with F-SBM as the sole source of crude protein had higher (p < 0.05) apparent ileal digestibility (AID) of DM (80.0 vs. 71.7%), ash (55.6 vs. 36.1%), CP (84.2 vs. 78.3%), NDF (70.9 vs. 66.0%), and ADF (62.4 vs. 53.3%) compared with pigs fed with unfermented soybean meal (UF-SBM).

CONCLUSIONS

A novel Bacillus subtilis strain CP-9 was isolated and characterized from camel dung for efficient fermentation of SBM. This bacterium ameliorates physico-chemical characteristics of F-SBM and improved nutrient digestibility in growing pigs.

SIGNIFICANCE AND IMPACT OF THE STUDY

Our data suggest that a low-cost solid-state SBM fermentation was developed using this newly isolated bacterium. The resultant F-SBM improved the nutrient digestibility in growing pigs.

Digestibility and metabolic utilisation of dietary energy in adult sows: influence of addition and origin of dietary fibre

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)0·75per 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 CH4were linearly related to the digestible total DF intake (+1·4 kJ/g). Fasting HP at zero activity averaged 260 kJ/kg BW0·75per d. Activity HP represented 20 % total HP, or 83 kJ/kg BW0·75per d on average. Total TEF and TEFltwere higher (P<0·05) for diet WB than for the other diets. However, total HP (406 kJ/kg BW0·75per 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.