Nutrient and energy digestibility of feed ingredients in pig diets is affected by physicochemical characteristics, animal factors and feeding levels. Therefore the objectives of this study were to quantify the contributions of the small intestine and large intestine to apparent total tract digestibility (ATTD) of nutrients and energy of diets formulated by graded inclusions of wheat bran, and the effects of graded inclusions of wheat bran on the nutrient digestibility and DE content at two growth stages, calculated by the difference method. Six light pigs (initial body weight [BW] 32.5±2.1 kg) and six heavy pigs (initial BW 59.4±3.2 kg) were surgically prepared with a T-cannula in the distal ileum. A difference method was used to calculate the nutrient and energy digestibility of wheat bran by means of comparison with a basal diet consisting of corn-soybean meal (0% wheat bran). Two additional diets were formulated by replacing 9.65% and 48.25% wheat bran by the basal diet, respectively. Each group of pigs was allotted to a 6×3 Youden square design, and pigs were fed to three experimental diets during three 11-d periods. Chromic oxide (0.3%) was included in all diets as an indigestible maker.
For the wheat bran diets, the AID and ATTD of dry matter (DM), ash, organic matter (OM), carbohydrates (CHO), gross energy (GE), and digestible energy (DE) decreased with increasing inclusion levels of wheat bran (p<0.05). While only AID of CHO and ATTD of DM, ash, OM, CHO, GE, and DE content differed (p<0.05) when considering the BW effect. For the wheat bran ingredient, there was a wider variation effect (p<0.01) on the nutrient and energy digestibility of wheat bran in 9.65% inclusion level due to the coefficient of variation (CV) of the nutrient and energy digestibility being higher at 9.65% compared to 48.25% inclusion level of wheat bran. Digestible energy content of wheat bran at 48.25% inclusion level (4.8 and 6.7 MJ/kg of DM, respectively) fermented by hindgut was significantly higher (p<0.05) than that in 9.65% wheat bran inclusion level (2.56 and 2.12 MJ/kg of DM, respectively), which was also affected (p<0.05) by two growth stages. This increase in hindgut fermentation caused the difference in ileal DE (p<0.05) to disappear at total tract level.
In summary, increasing the inclusion level of ingredients can reduce the risk of calculation errors when determining the nutrient and energy digestibility of fibrous ingredients. This research also showed a higher nutrient digestibility of wheat bran ingredients by pigs when increasing inclusion levels are used. In addition, DE content of wheat bran could be better fermented in the large intestine at higher inclusion due to the increasing ability of hindgut fermentation.
Huang, Q., Su, Y.B., Li, D.F., Liu, L., Huang, C. F., Zhu, Z.P. and Lai, C.H. 2015. Effects of Inclusion Levels of Wheat Bran and Body Weight on Ileal and Fecal Digestibility in Growing Pigs Asian-Australas J Anim Sci. 28: 847–854. doi:10.5713/ajas.14.0769