The objective of the present study was to evaluate the agreement of two methods for the determination of chromium oxide in feed, duodenal contents and faeces in the investigation of feed digestibility. Four Holstein steers Γtted with permanent ruminal and duodenal cannulae were used in a 4 ] 4 Latin square design experiment. Steers were fed diets varying in urea content three times daily, restricted at a level equivalent to 2Γ5% of live body weight (dry matter basis). Faecal and duodenal Γuxes of dry matter and nitrogen were estimated using chromium oxide as a indigestible marker. The equivalent (Cr 2 O 3 ) concentration in the solution resulting from acid digestion of the samples Cr 2 O 3 was measured by chromium determination by simple photometry at 350 nm and by Γame atomic absorption spectrometry. Chromium concentrations in feed, duodenal contents and faeces and ruminal and total digestibilities of dry matter and nitrogen were a β ected by the chromium determination methods used. Despite the fact that the AAS method is more precise and sensible, sometimes its utilisation is limited by availability of equipment. In this situation, the chromium determination by photometric method can be a feasible alternative, since proper corrections in optical density readings are done.
1998 SCI.