The objective of this research was to evaluate the chemical composition, selectivity, partial intake, milk production and concentration of urea nitrogen in blood and milk in Gyr x Holstein dairy cows on silvopastoral systems with different densities of Leucaena leucocephala trees. The study was carried out in the Chaco Farm - department of Tolima - Colombia. The treatments were: T1: Cynodon nlemfluensis pasture without trees; T2: C. nlemfluensis + 1264 trees / ha of L. leucocephala; T3: C. nlemfluensis + 4255 trees / ha of L. leucocephala and T4: C. nlemfluensis + 9899 trees / ha of L. leucocephala. Four experimental periods of 32 days were evaluated and 16 F1 (Gy r X Holstein) cows were used. Differences (P <0.05) were observed in relation to the dry matter of both C. nlemfluensis and L. leucocephala. There was high selectivity for grass (P <0.05). The dry matter intake decreased with the increase in the density of L. leucocephala trees in period 3, in the other periods no differences were observed (P> 0.05). As the density of L. leucocephala trees increased, the values of urea nitrogen in blood and milk increased (P <0.05). Milk production was not altered by treatments. It is concluded that F1 (Gyr X Holstein) cows in silvopastoral systems have a high selectivity and partial intake of grass, and higher levels of blood and milk urea nitrogen.