The botanical composition of pre-established mixtures of six forages species was estimated after in vitro digestion times and compared with the real composition. Three mixtures of six species of known participations were made up in the rainy and dry seasons and estimated through the microhistological technique. The sampling season interfered with the estimates of only one of the mixtures. In spite of the statistical differences between the real composition of the mixtures and their estimates, the similarity indices for the periods were superior to 85%. The digestion time influenced mixtures estimates, according to the percentage of the species participation. The three mixtures estimates were identical after 48 and 72 hours of digestion. The digestion of the samples either improved or worsened the estimates, according to the percentage of participation and to species resistance. The digestion process must not be considered as the only factor of variation when this technique is utilized, since the similarity indices between the periods, the digestion time and the real composition were superior to 75%.
real composition; similarity index and microhistological technique
