Compatibility of using TiO2 and the faecal near-infrared reflectance spectrometry for estimation of cattle intake

Combining titanium dioxide (TiO2) as indigestible marker to faecal near-infrared reflectance spectrometry (F-NIRS) can be used to determine cattle feed intake and quality of ingested forage if F-NIRS spectra are not modified by the marker. This study aimed at determining the compatibility of TiO2 with F-NIRS. Three dry cows were fed a standard hay-based diet for three weeks supplemented with a daily dose of 0.1 % (10g) TiO2 during the last two weeks of the experiment. Faeces samples were collected every day and analysed for TiO2 and F-NIRS. Results suggest that TiO2 did not interfere with F-NIRS analyses. The calculations of crude protein, NDF, ADL contents, as well as dry matter intake did not change over time with increasing TiO2 in the faeces (P > 0.05). Slight differences observed for other predicted parameters seemed to be independent from TiO2. The higher Mahalanobis distance (H) for chemical composition (H = 7.2) independent from TiO2 inclusion could indicate that faecal spectra did not correspond exactly to the prediction database. Although 0.1% incorporation of TiO2 seem not to interfere with F-NIRS measurements, caution must be taken with higher levels of TiO2 as nothing indicates that interference could not appear.