Effects of body weight and fiber sources on fiber digestibility and short chain fatty acid concentration in growing pigs

Objective: The study was conducted to determine the effects of body weight (BW) and fiber sources on nutrient digestibility, fiber fermentation and short chain fatty acids (SCFA) concentration in different intestinal segments of growing pigs fed high-fiber diets. Methods: Nine barrows with initial BW of 25.17 +/- 0.73 kg and 9 barrows with initial BW of 63.47 +/- 2.18 kg were allotted to a duplicate 9x2 Youden Square design with 3 dietary treatments and 2 periods. The dietary treatments were formulated with 3 different high-fiber ingredients: corn bran, sugar beet pulp, and soybean hulls, respectively. Each diet was fed to 3 barrows with different stage of BW in each period. Results: There were no differences in the apparent ileal digestibility (AID) of most nutrients between pigs at different BW stages. Pigs at 60 kg had greater (p<0.05) apparent total tract digestibility (ATTD) of total dietary fiber (TDF), soluble dietary fiber (SDF) and insoluble dietary fiber (IDF), and had greater (p<0.05) hindgut disappearance of IDF and cellulose than pigs at 25 kg. The acetate, propionate and total SCFA concentrations in ileal digesta and feces of pigs at 60 kg were greater (p<0.05) than those of pigs at 25 kg. In addition, fiber sources affected (p<0.05) the AID of gross energy (GE), organic matter (OM), ether extract (EE), crude protein, SDF and hemicellulose, the hindgut disappearance and ATTD of dietary fiber components, the lactate and propionate concentrations in ileal digesta and the butyrate, valerate and total SCFA concentrations in feces. There were interactions (p<0.05) between BW and fiber sources on the AID of GE, OM, EE, SDF, hemicellulose, the ATTD of EE, TDF, and IDF, and the hindgut disappearance of SDF and hemicellulose. Conclusion: Increasing BW mainly improved the digestibility of dietary fiber fractions, and the dietary fiber sources influenced the digestibility of almost all the dietary nutrients in growing pigs.