Comparison of Three Digestibility Markers in Beef Cattle Fed Finishing Rations Containing Different Sources of Supplemental Fat

Abstract

Beef cattle production is profoundly dependent on the diets provided to the cattle and their ability to promote growth. Dietary markers significantly aid beef cattle nutritionists by providing an index to measure diet efficiency and feed bioavailability throughout the digestive system. This study compares two external dietary markers, chromium oxide (Cr2O3) and titanium dioxide (TiO2), and one internal marker, acid detergent insoluble ash (ADIA) with the objective of validating titanium oxide as a marker. Fecal and duodenal samples were collected from four ruminally and duodenally cannulated steers, over four trial periods with each period having duration of twelve days. External dietary markers were hand-mixed and administered daily in a fat-supplemented concentrate diet. The interaction between marker and treatment was significant (P<0.05) for OMD and ADF. Digestibilities determined by TiO2 and Cr2O3 were significantly different (P<0.05) for all nutrients observed; however TiO2 and ADIA differed significantly only for organic matter digestibility (OMD). This project did not provide definitive data regarding the suitability of any of the markers for measuring digestibility.