Effect of fiber on physiochemical properties of digesta and fecal microbial composition in pigs

Abstract: This study was conducted to investigate the effects of different dietary fiber sources on physicochemical properties of digesta and fecal microbial composition in growing pigs. Seven castrated Yorkshire pigs with an initial weight of 24.8 kg (SD 3.0) fitted with a post valve t-caecum (PVTC) cannula were used in a change-over experiment with four periods and four diets. The diets consisted of a basal part and a fibre part, including either a soluble ((Chicory (CH) and Sugar beet pulp (SBP)) or an insoluble ((Wheat bran (WB) and Grass meal (GM)) fibre source. Each experimental period was two weeks and consisted of one week for adaptation to each diet followed by one collection week. Fecal sampling occurred the four first days of each collection period and the ileal digesta samples were collected during fifth and seventh day of the second week. Overall, the effect of various diets on ileal and fecal pH were significant (P< 0.05). Pigs fed with GM diets had a higher ileal pH compared to pigs that were fed SBP and WB diets. Pigs fed with CH diets showed higher fecal pH compared to pigs fed with WB and GM diets. Different dietary fiber diets had no significant effect on ileal digesta viscosity (P> 0.05). The effect of different type of dietary fiber on fecal and ileal dry matter (DM) was significant (P< 0.05). The pigs fed with SBP diet had highest fecal DM followed by pigs fed with WB diet. The pigs fed with GM and CH diets showed similar fecal DM which was lower than SBP and WB diets. The ileal DM was higher in the pigs fed with WB diet than the pigs fed with the other diets. The effect of different type of dietary fiber diet on fecal microbial composition was analyzed by Terminal Restriction Fraction Length Polymorphyism (T-RFLP) and showed significant differences among the diets, however the total diversity did not differ due to diet (P> 0.05). This study showed that pigs fed by CH, have more unique fecal microbial composition compared to the pigs fed with the other diets. TRF 160 and TRF 412 identified as Prevotella had higher relative abundance in pigs fed with the CH diet.TRF 275 identified as Megasphaera elsdenii had the highest relative abundance in pigs fed with WB diets. Generally, the effects of the studied fiber sources on physicochemical properties and gut microbiota seems to be ingredient specific. All animals stayed healthy on all diets which mean that all of our experimental dietary fiber sources can be used in pig nutrition at the inclusion level tested in our experiment.