Effect of resistant starch on the intestinal health of old dogs: fermentation products and histological features of the intestinal mucosa†
Resistant starch (RS) is the sum of the starch and its degradation products that resist digestion in the small intestine and reach the colon (Nugent, 2005). In the colon, RS is readily fermented, altering the colon's environment through effects on bacterial populations and fermentation activity, reducing faecal pH, and increasing butyrate concentration (Birkett, Muir, Phillips, Jones, & O`Dea, 1996; Simpson, 1998). Short‐chain fatty acids (SCFA) derived from the bacterial fermentation of RS are the major substrates for the energy metabolism of colonocytes, and specifically, butyrate acts as a growth factor for a healthy epithelium in the colon (Ashwar, Gani, Shah, Wani, & Masoodi, 2016; Bird, Vuaran, Brown, & Topping, 2007; Birt et al., 2013; Zaman & Sarbini, 2016). Butyrate stimulates the regeneration of injured intestinal tissue after inflammation and may have a role in the prevention of several types of colitis in animals and humans (Brouns, Kettlitz, & Arrigoni, 2002; Moreau et al., 2003; Scheppach, 1994).
Based on this, it is possible that the intake of RS by old dogs promotes the production of SCFA and specifically of butyrate, favouring nutrient supply to the intestinal mucosa and possibly attenuating some effects of the age‐related alterations in their histological structure. Therefore, the objectives of this study were to evaluate the effects of two concentrations of RS in extruded diets on nutrient and energy digestibility, faecal concentration of fermentation products and IgA, and the histological features of the gastrointestinal mucosa of old dogs.