The tree cover in pastureland contribute to improve the animal productivity through reducing the heat stress, and also benefits the soil conservation and biodiversity. The objective of this study was to know the effects of tree crown cover on the availability of Brachiaria brizantha grass. A census of trees in 53 plots was taken out and there were selected the 12 most abundant in pastureland for monitoring the grass availability under the canopy and in open pasture. Also, there was determined the relationship between tree cover and grass availability. Beneath canopy the grass availability showed reductions between 4 and 97% when compared to open pasture, except for Acrocomia aculeata specie which was higher under canopy (9%). The grass availability was reduced according to increasing the tree crown cover in pastureland. It is concluded that grass availability under tree canopy varied among species and there was a good negative relationship between crown cover percentage and grass availability.