Evaluation of titanium dioxide as a digestibility marker for cattle.

Three studies were conducted to evaluate titanium dioxide (TiO 2 ) as a digestibility marker for cattle. In Exp. 1, eight steers consumed prairie hay ad libitum with or without dietary supplements. Fecal recovery of TiO 2 averaged 93% and was not affected (P = 0.47) by supplement. Digestibilities calculated with reference to TiO 2 were not different (P = 0.15) from those based on total fecal collections. In Exp. 2, two steers were limit-fed corn-based diets. Fecal recovery of TiO 2 averaged 95% and that of chromic oxide (Cr 2 O 3 ) averaged 113%. Digestibilities calculated with reference to TiO 2 were underestimated (P < 0.01) by 1.1 percentage units relative to those based on total fecal collections, and those calculated with reference to Cr 2 O 3 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. Fecal recovery of TiO 2 averaged 90%, whereas that of Cr 2 O 3 averaged 98%. Digestibilities calculated with reference to TiO 2 were underestimated (P < 0.01) by 1.6 to 4.3 percentage units, whereas those calculated with reference to Cr 2 O 3 were not different (P = 0.31) from those based on total fecal collections. Future research is warranted to determine the usefulness of TiO 2 in measuring digestibility in cattle.