Comparison of four digestibility markers to estimate fecal output of dogs

Twelve adult beagle dogs (10.6 ± 1.4 kg) were fed extruded dog diets in which the starch sources were whole sorghum, sorghum flour, sorghum mill-feed, or an equal combination of rice, corn, and wheat. The experiment was conducted as a replicated Latin square design digestibility study. Estimates of fecal organic matter (OM), crude protein (CP), crude fat (CF), and gross energy (GE) outputs were determined by four methods: total fecal collection (TFC), chromic oxide (Cr(2)O(3)), titanium dioxide (TiO(2)), and acid insoluble ash (AIA). The correlation among the fecal output estimates by the four methods by partial correlation coefficients from the Error SSCP Matrix (Pearson) were considered significant at P < 0.05. The external markers, Cr(2)O(3) and TiO(2), had a higher (P < 0.05) OM fecal output Pearson correlation to TFC than the intrinsic marker AIA (R = 0.931 for Cr(2)O(3) vs. TiO(2); R = 0.559 for TFC vs. Cr(2)O(3); R = 0.592 for TFC vs. TiO(2); R = 0.291 for AIA vs. TFC). Interestingly, TiO(2) highly correlated (P < 0.05) to Cr(2)O(3) (R = 0.93 for OM), and was also correlated highly to TFC and AIA. The study suggests that TiO(2) may be a preferred marker to estimate fecal output in dogs vs. Cr(2)O(3). The use of AIA represents a potential option for determining digestibility for diets in which external markers are impractical.