Extension Education - Dairy Science

Adult Beagles (36) and mixed-strain hounds (4), in 8 groups of 5 dogs each, were used to evaluate organic matter digestibility of 4 diets having no fibrous ingredient (CON), beet pulp (BP), soybean hulls (SH), or cellulose (CEL), with or without 0.11% mannan oligosaccharide (MOS; Bio-Mos r , Alltech, Inc., Nicholasville, KY). Analyzed total (and soluble) fiber percents, respectively, were: 8.1 (2.4), 15.3 (3.7), 16.7 (1.5), and 15.6 (1.7). The study conducted 6 times involved a 21-d adaptation period and a 5-d total fecal collection period. Insoluble fiber digestibility was greatest for SH diet whereas CON, BP, and CEL diets were similar. Insoluble fiber of SH was about 25% more fermentable than that of BP though nonsignificant. Soluble fiber digestibility was variable and not significantly different among fiber sources. The MOS increased soluble fiber digestibility across all fiber sources (P < 0.05; 72.9 vs 61.5%, on average), indica-ting a strong beneficial effect on microbial metabolism due to increased proliferation of the fermentation microbe population. In vitro fermentation of starch, BP, SH, or CEL was evaluated using inocula from feces of 12 dogs (3 from each of the CON and BP diets with and without MOS). Organic matter digestibility of BP and SH was improved with BP + MOS diet but not CON + MOS diet fecal inoculum , indicating that some adaptation period was required for MOS to lead to changes in microbial metabolism.. However, fecal inoculum from dogs fed BP + MOS diet decreased acetate, propionate, and total volatile fatty acids using BP or SH substrates and fecal inoculum from dogs fed CON + MOS diet increased acetate and total volatile fatty acids using starch. Histology revealed the number of colonic mucous secreting goblet cells was greater for BP and SH than CON and CEL diets in response to amount of fermentation not fiber per se. Addition of MOS to dry dog food improved fiber digestibility and altered intestinal fermentation patterns.