Relationship between Dietary Fiber Fermentation and Volatile Fatty Acids’ Concentration in Growing Pigs

SIMPLE SUMMARY: The study suggests differences in fermentable capacity of fibrous feed ingredients are associated with fiber composition in pig. Results demonstrate that the fiber digestibility of oat bran, sugar beet pulp and soybean hulls is greater than for corn bran, wheat bran and rice bran in the pig intestine. Furthermore, results indicate that volatile fatty acids’ concentration (VFA) is positively correlated primarily with insoluble dietary fiber (IDF) fermentation, and the digestibility of IDF is the best single variable to predict fecal VFA concentrations. The contribution of this study is to provide instructions on how to implement fiber-rich ingredients effectively in the feed formulation for swine. ABSTRACT: This study was conducted to determine whether differences in fiber fermentation in fiber-rich feed ingredients exist and to assess relationship between fiber fermentation and concentration of volatile fatty acids (VFA) in pig. Castrated males (barrows) were allotted randomly to six diets formulated with different amounts of wheat bran (WB), corn bran (CB), sugar beet pulp (SBP), oat bran (OB), soybean hulls (SH) or rice bran (RB). The apparent ileal digestibility (AID) of soluble dietary fiber (SDF) for OB and SH diets was greater (P < 0.05) than for the other diets. The fermentation of total dietary fiber (TDF) and insoluble dietary fiber (IDF) in the hindgut were greater (P < 0.05) for SBP and SH diets than for WB, CB, OB and RB diets. The apparent total tract digestibility (ATTD) values of all fiber components in SBP, SH and OB diets were greater (P < 0.05) than for WB, CB and RB diets. The concentration of VFA in feces was positively correlated with the ATTD of IDF and cellulose, and ATTD of IDF is the best factor for predicting fecal VFA concentration. Overall, dietary fiber source affected fermentable characteristics of fiber components in the different digestive segments of pig intestine.