Dietary fiber for cats: in vitro fermentation of selected fiber sources by cat fecal inoculum and in vivo utilization of diets containing selected fiber sources and their blends.

Two experiments were conducted to evaluate the addition of single sources and blends of dietary fibers to cat diets. In Exp. 1, fermentability of selected fibrous substrates by cat fecal microflora was evaluated. After 24 h of fermentation, OM disappearance (OMD) and total short-chain fatty acid (SCFA) production were greatest (P < .05) for citrus pectin, guar gum, and locust bean gum, whereas Solka Floc resulted in the least (P < .05) OMD and total SCFA production. In Exp. 2, six diets were formulated based on results of Exp. 1. The highest (P < .05) digestibilities of DM and OM occurred when cats consumed the diet with no supplemental fiber, and the lowest (P < .05) digestibilities occurred when cats consumed the SCFA blend (SC) diet. Nitrogen and lipid digestibilities also were lowest (P < .05) for cats consuming the SC diet, whereas total dietary fiber (TDF) digestibility (P < .05) was greatest for cats consuming the beet pulp, SC, and combination blend diets. Fecal consistency scores were highest (P < .05) for cats consuming the SC diet, indicating liquid, unformed stools. In conclusion, the in vitro fermentation technique was reasonably accurate in predicting in vivo digestion of fiber. The SC diet, which contained the most fermentable fibers, severely decreased nutrient digestibility and resulted in poor stool characteristics. Diets that contain moderately fermentable fiber provide fermentation end products that may be important in maintaining the health of the gastrointestinal tract of the cat.