The objective of this study was to determine possibilities of in vitro methodologies developed for the Ankom DaisyII Incubator for prediction of accurate assessment of in vivo equine dry matter (DM) and organic matter (OM) digestibility, when equine feces were used as the inoculum source. Five mature horses (geldings and mares) were used in experiments to determine in vivo dry matter and organic matter digestibility of corn silage. Horses were individually housed and fed. Feces were collected and deep freezing until to freeze drying, chemical analyses and calculate in vivo digestibility during each experimental period (2 x 3 days). Digestion of the same corn silage was evaluated by in vitro method using the DaisyII Incubator. Incubation vessel contained 11 filter bags (10 for determination DM, OM and one blank bag for correction). Samples were incubated for 72 h.