Quantification of short-chain fatty acids and energy production from hindgut fermentation in cannulated pigs fed graded levels of wheat bran1

Abstract

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.

The gut microbiota and metabolic disease: current understanding and future perspectives

“…However, Asian/African diets have higher fibre content, which may indicate a higher energy contribution from fibre fermentation to the host. This was corroborated in a study in pigs, which have similar intestinal functions to humans, showing that an increase in dietary fibre from 75 to 147 g kg −1 increased energy contribution from 10.7% to 24.2% . Thus, a slight increase in microbial fermentation (1%) could provide 20 kcal day −1 extra energy based on a diet of 2000 kcal day −1 , resulting in 1 kg of weight gain per year .…”

Oat bran and wheat bran impact net energy by shaping microbial communities and fermentation products in pigs fed diets with or without xylanase

“…The design of 6 open-circuit respiration chambers were reported by van Milgen et al [13] and Lyu et al [11]. Volume of each chamber was approximately 7.8 m 3 , and relative humidity in chamber was controlled at 70%. During the feeding period, the temperature was 22°C, and it was increased to 24°C on the fasted day.…”

“…Major end products from these fermentations are the short-chain fatty acids (SCFA) [2], mainly acetate, propionate, and butyrate. Recent studies show that SCFA from microbial fermentation generates 11% to 24% of the total digestible energy (DE) as wheat bran (WB) level increases from 10% to 30% when fed to pigs [3]. It suggests that DF has a final impact on energy metabolism by shaping microbes and regulating SCFA production [4].…”

Flaxseed meal and oat hulls supplementation: impact on predicted production and absorption of volatile fatty acids and energy from hindgut fermentation in growing pigs1

“…Contribution of available energy from hindgut fermentation (%) = (energy absorbed from hindgut VFA (kcal/kg DM feed) / (energy digested in the ileum (kcal/kg DM feed) + energy absorbed from hindgut VFA(kcal/kg DM feed))) × 100 (Iyayi and Adeola, 2015).…”

“…Previous studies have indicated that nutrient utilization and performance is depressed when pigs are fed nutritionally-balanced high-fiber diets that contain added fat (Bakker, 1996;Gutiérrez et al, 2013). An increase in DF cause a reduction in digestible energy of pig diets (Bach Knudsen and Hansen, 1991) and promotes hindgut VFA production and absorption (Iyayi and Adeola, 2015;Montoya et al, 2016). Different fiber sources are fermented at different rates and the solubility of DF is important in determining fermentability of DF and the quantity of VFA produced (Bach Knudsen, 2001;Zhou et al, 2018).…”