Two assays were carried out to evaluate the precision of internal markers in relation to the total feces collection method to estimate the apparent digestibility of nutrients in diets for equines. Six adult crossbreed horses, averaging seven years old, were used. In the first assay, the values of digestibility of the nutrients of coast-cross hay using HCl-insoluble ash (AIA), acid detergent insoluble ash (ADIA) and lignin by the total feces collection method were compared. In the second assay, the digestibility of the nutrients of the combination of elephant grass and coast cross hay was compared by the two methods. A completely randomized block design was used, where each horse made up a block and the methods of digestibility determination, the treatments. In both assays, the results showed that both AIA and ADIA were efficient as internal markers to estimate the apparent digestibility of the nutrients of coast-cross hay and of the combination of elephant grass and coast-cross hay. For the horses fed coast-cross hay, the average recovery in the feces of AIA and ADIA was of 100.12 and 99.66%, respectively. For the horses fed with hay and elephant grass the recovery were 101.32 and 96.33%, respectively. The lignin was unsuitable to estimate the apparent digestibility of nutrients in the tested diets.
digestibility; horses; indicators
