Effects of Dietary Fiber Levels on Weight Gain, Cecal Volume and Volatile Fatty Acid Production in Rabbits

Abstract

Two groups of 10 rabbits each, housed individually, were fed ad libitum quantities of a diet containing either 14.7% or 29.4% acid detergent fiber for 11 weeks following weaning. The effects of dietary fiber level on weight gain, rate of ingesta passage and cecal volume were determined, as were nutrient digestibilities. Volatile fatty acids in the cecal and fecal contents were determined, in addition to production rates in the cecum. The high fiber diet resulted in a statistically significant decrease in weight gain and digestibility of dry matter and energy, and a significant increase in cecal volume/kilogram body weight. Fiber digestibility was maintained at the same level (34%) on the high fiber diet as on the lower fiber diet. Rates of cecal acetate and propionate production were similar on both diets, but butyrate production was significantly higher on the low fiber diet. It was estimated that the cecal fermentation in rabbits, regardless of dietary fiber level, produced a quantity of volatile fatty acids equivalent to 10 to 12% of the daily basal caloric requirement.