Selectivity of forage species by cattle grazing in seminatural grasslands was evaluated at different hierarchical levels (feeding site and individual species) with two types of pastures grazed by two animal categories (lactating and dry cows), which constituted the treatments, each with six replicates (paddocks).The feeding behavior was monitored in two altitudinal strips of the landscape, the high and low zones, during both the dry and wet seasons of 2005. Selectivity indexes (SI) for individual species varied according to treatment and season. Grasses made the greatest contribution to the diet in both seasons and altitudinal zones. In the low zone grasses represented 93,5 and 74,5 % of the diet during the wet and dry season, respectively; whereas for the high zone corresponding values were 81,6 and 79,2%, respectively. During the dry season several woody perennials showed higher SI than grasses and other herbaceous species. Animal selectivity is a relative index as it is infl uenced by the seminatural grasslands botanical composition, as infl uenced by the altitudinal position in the landscape, type of pasture and season.