PSXIII-37 A comparison of different methods of estimation of dry fecal output in dogs

Abstract Total fecal collection (TFC) is the gold standard to estimate nutrient digestibility; however, it is difficult to collect all fecal material, especially for animals housed in confined space or that are prone to coprophagy. Instead, markers can be used to estimate digestibility. Markers can include intrinsic diet components like acid insoluble acid (AIA) or added to the diet like chromium sesquioxide (CR) or titanium dioxide (TI). These elements don’t have a physiological function, and are not digested, or absorbed by the animal. Chromium sesquioxide is most commonly used. However, it is a known carcinogen to workers and animals over extended exposure periods. Titanium dioxide (TI) is a food coloring generally recognized as safe (GRAS) that conforms to the required features needed for a marker. Our hypothesis was that TI would be a preferred marker to estimate digestibility among the other methods. Therefore, the objective of this meta-analysis was to compare the different methods to estimate digestibility across several studies. Data from four different digestibility experiments using the same animals, experimental procedures, and design were compiled and analyzed. Using the GLM procedure (SAS v. 9.4) Pearson correlation coefficients for dry fecal output between TFC, CR, TI, and AIA were calculated with multivariate analysis of variance, on two response variables: experiment and dog. All method correlations were significant (P