Quantification of short-chain fatty acids and energy production from hindgut fermentation in cannulated pigs fed graded levels of wheat bran.J Anim Sci. 2015 Oct; 93(10):4781-7.JA
This study investigated the amount of energy available to growing pigs from fermentation of dietary fiber in the hindgut. Eighteen growing barrows, fitted with a simple T-shaped cannula at the terminal ileum, were allocated to 3 experimental diets in a completely randomized design. The 3 diets were a standard-fiber diet (SFD), which contained 75.1 g NDF/kg diet; a medium-fiber diet (MFD) of 105.7 g NDF/kg diet; and a high-fiber diet (HFD), which contained 146.9 g NDF/kg diet. Each diet had 6 replicate pigs. After a 5-d period of adjustment of the pigs to the cage environment, feces were collected on d 6 and 7 and ileal digesta on d 8 and 9 and subsequently freeze-dried. Fecal slurry from a pig was used to inoculate the ileal digesta from the same pig. The amount of energy available was calculated from the amount of short-chain fatty acids (SCFA) produced from a 48-h in vitro fermentation of the ileal digesta. Increasing NDF enhanced (< 0.01) the ileal DM flow and DM in feces. The energy available in the foregut was reduced (< 0.05) from 3,360 to 2,974 kcal/kg feed DM and increased (< 0.01) from 619 to 1,009 kcal/kg feed DM produced in the hindgut with increasing dietary NDF. The amount of SCFA increased (< 0.01) with higher dietary NDF. Acetic acid was highest (< 0.01) in the HFD whereas propionic and valeric acids were highest (< 0.05) in the SFD. The amount of butyric acid was not affected by diet. The amount of energy contributed from SCFA fermentation to total tract digestible energy increased (< 0.01) from 10.7 to 24.2% as dietary NDF level increased from 75 to 147 g/kg feed. The results of the study showed that increasing level of dietary NDF resulted in reduced energy digestibility in the foregut of growing pigs with a corresponding increase in the amount of energy from microbial fermentation in the hindgut.