Use of indigestible markers to estimate the apparent dry matter digestibility of diets containing a cocoa by-product

Fecal production and apparent dry matter digestibility (ADMD) were evaluated using external markers (chromium oxide; titanium dioxide; isolated, purified, and enriched lignin (LIPE®); and isolated, purified, and enriched lignin nanoparticles (NANOLIPE®) and internal markers (indigestible DM (IDM), indigestible neutral detergent fiber (INDF), and indigestible acid detergent fiber (IADF) in diets based on Tifton 85 bermuda grass (Cynodon sp.) hay containing different concentrations of a cocoa by-product. Sixteen crossbred (Holstein × Zebu) dairy heifers with a mean live weight of 363.00 ± 27.70 kg were evaluated and distributed in a completely randomized block design with a split-plot arrangement. The plots corresponded to the diets, which differed in the substitution of bermuda grass hay with different concentrations (0, 8, 16, and 24% of DM) of the cocoa by-product, whereas the splitplots represented the indigestible markers. Chromic oxide, LIPE®, NANOLIPE®, and INDF accurately estimated ADMD and fecal production whereas titanium dioxide, IDM, and IADF did not accurately estimate these parameters.