Evaluation of titanium dioxide as a digestibility marker for cattle

Three studies were conducted to evaluate titanium dioxide (TiO2) as a diges tibility marker for cattle. In Exp. I, eight steers consumed prairie hay ad libitum with or without dietary supplements. Fecal recovery of TiO2 averag ed 93% and was not affected (P = 0.47) by supplement. Digestibilities calcu lated with reference to TiO2 were not different (P = 0.15) from those based on total fecal collections. In Exp. 2, two steers were limit-fed corn-base d diets. Fecal recovery of TiO2 averaged 95% and that of chromic oxide (Cr2 O3) averaged 113%. Digestibilities calculated with reference to TiO2 were u nderestimated (P < 0.01) by 1.1 percentage units relative to those based on total fecal collections, and those calculated with reference to Cr2O3 were overestimated (P < 0.01) by 2.0 percentage units. In Exp. 3, eight steers in a replicated 4 x 4 Latin square consumed corn-based diets ad libitum. Fe cal recovery of TiO2 averaged 90%, whereas that of Cr2O3 averaged 98%. Dige stibilities calculated with reference to TiO2 were underestimated (P < 0.01 ) by 1.6 to 4.3 percentage units, whereas those calculated with reference t o Cr2O3 were not different (P = 0.31) from those based on total fecal colle ctions. Future research is warranted to determine the usefulness of TiO2 in measuring digestibility in cattle.