Use of energy dispersive X-ray fluorescence (EDXRF) spectrometry to determine external markers in animal intake estimation trials

The study evaluated the accuracy of EDXRF spectrometry for measuring titanium (Ti) and chromium (Cr) in fecal and dietary samples as markers for fecal output and forage intake in grazing animals. Standard addition calibrations were performed using Tifton hay and sheep feces. The sheep feces standard addition calibration aimed to estimate Cr and Ti in various animal feces fed on grass, while the Tifton hay standard addition calibration aimed to estimate Cr and Ti in different materials, such as concentrate and mineral salt with Cr and Ti, by diluting small amounts of these samples into Tifton hay. A strong correlation was observed between added Ti/Cr and their detected intensities by EDXRF. Improved linearity was achieved when the X-ray fluorescence intensity was normalized by Rh kα Compton peak. The standard addition calibration for sheep feces efficiently estimated Cr and Ti, while it was less effective for cattle and horse feces. The Tifton hay standard addition calibration showed appropriate recovery for concentrate standards and mineral salt standards. EDXRF spectrometry is cost- and time-effective for Ti and Cr analysis in fecal and dietary samples, though specific calibrations are needed due to matrix variations.