This research aimed to compare dry matter digestibility coefficient (DMDC) of horse diets by total feces collection (TC) and internal markers, indigestible cellulose (iCEL), indigestible acid detergent fiber (iADF) and acid insoluble ash (AIA). Sixteen adult mares of Mangalarga Marchador breed averaging from 3.5 to 18.4 years and 394.80 ± 46.22 kg were assigned to a randomized block design with four replicates. Diets were formulated to be isoprotein and isoenergetic and composed of coastcross hay (Cynodon dactylon cv. Coast cross) and 60:40 concentrate. Evaluation of DMDC estimated by the markers was performed by a model considering the bias, i.e., the difference between DMDC estimated by marker and by TC. No effect of animal age on DMDC. Among the evaluated markers, iADF was more accurate. Regarding precision, no differences were observed among markers. Concerning robustness, dry matter intake and DMDC affected iADF and iCEL estimates, whereas only DMDC affected AIA estimate. Markers recoveries were 98.49, 94.49 and 144.5% for iADF, iCEL e AIA, respectively and, only iADF recovery did not differ from 100%. Markers ranking concerning accuracy, precision and robustness were as follows: iADF, AIA and iCEL.
apparent digestibility; equine; markers
