A Low to Medium-Shear Extruded Kibble with Greater Resistant Starch Increased Fecal Oligosaccharides, Butyric Acid, and Other Saccharolytic Fermentation By-Products in Dogs

Abstract

The objective of this study was to assess whether diets with increased resistant starch (RS) had a positive effect on markers of colonic health in dogs. Three identical diets were extruded with high, medium and low shear (HS, MS and LS) to incrementally increase RS, and fed to 24 dogs in a replicated 3 × 3 William’s Latin square design for 28-day periods. Fasting blood and fresh feces were collected on the last week of each period. Fecal quality was maintained among treatments. Gut integrity markers were measured by ELISA. Fecal short-chain fatty acids (SCFAs) were measured by LC MS/MS. In addition, the microbiota of dogs was determined from fresh feces by 16s rRNA high throughput sequencing. Untargeted metabolomics of both feces and serum were determined by UPLC. Data were analyzed using mixed models. There were no treatment effects on satiety hormones or gut integrity markers. Dogs fed LS or MS diets had marginal evidence (p < 0.10) for decreased fecal pH and for higher concentration (p < 0.05) of butyric acid and fecal oligosaccharides, succinate and lactate. Also, dogs fed the MS or LS diets had a shift towards more saccharolytic bacteria.

Processing of corn-based dog foods through pelleting, baking and extrusion and their effect on apparent total tract digestibility and colonic health of adult dogs

“…Gelatinized starch provides functionality to the food, making it more accessible for digestion by mammalian enzymes. In contrast, a portion of the ungelatinized starch resists digestion at the SI (RS type 2) and promotes health benefits as a prebiotic in the large intestine ( Peixoto et al, 2018 ; Ribeiro et al, 2019 ; Jackson et al, 2020 ; Corsato Alvarenga et al, 2021c ).…”

“…In previous work, in vitro RS did not correlate with in vivo ileal starch digestibility of dogs ( Murray et al, 1999 ). However, a recent study using a corn recipe produced via extrusion at three levels of thermomechanical energy found that minimal changes in RS measured using the same in vitro protocol ( McCleary et al, 2002 ) were sufficient to positively impact markers of gut health ( Corsato Alvarenga et al, 2021c ). We expected similar findings in the present study.…”

“…We expected similar findings in the present study. However, one needs to take into consideration that there are several physiological factors that in vitro methodologies do not account for, including actual gastric residence time, small intestine passage rate, hormones involved in the digestion process ( Dhital et al, 2017 ), and mastication intensity ( Ranawana et al, 2010 ) among other individual factors, which could be impacted by different processing methods (i.e., vs. all extruded kibbles at different cooking intensities; Corsato Alvarenga et al, 2021c ). These differences between in vitro and in vivo digestion might help explain the differing results.…”

“…Starches, in particular, play an important role in food particle binding and matrix development in most processed pet foods. While highly cooked and digestible starches increase the overall digestibility of food, foods produced with lower thermomechanical energy may shift the starch nutrition from being absorbed as glucose at the small intestine (SI) to having a more compact structure that is resistant to mammalian enzymes (resistant starches [RS]; Peixoto et al, 2018 ; Ribeiro et al, 2019 ; Jackson et al, 2020 ; Corsato Alvarenga et al, 2021c ). These RS act as prebiotics by becoming substrates for beneficial saccharolytic bacteria in the distal portions of the large intestine ( Peixoto et al, 2018 ; Ribeiro et al, 2019 ; Jackson et al, 2020 ; Corsato Alvarenga et al, 2021c ).…”

“…These RS act as prebiotics by becoming substrates for beneficial saccharolytic bacteria in the distal portions of the large intestine ( Peixoto et al, 2018 ; Ribeiro et al, 2019 ; Jackson et al, 2020 ; Corsato Alvarenga et al, 2021c ). The most relevant biomarkers of RS fermentation by the colonic microbiota of dogs are straight-chain short-chain-fatty acids (SCFA), such as butyrate ( Peixoto et al, 2018 ; Jackson et al, 2020 ; Corsato Alvarenga et al, 2021c ), which is the preferred energy substrate of colonocytes ( Bergman, 1990 ) and has anti-inflammatory properties that enhance homeostasis and colonic immunity ( Bedford and Gong, 2018 ).…”