Supplementation with legume fodder during the dry season is a strategy to improve animal performance. The results obtained in silvopastoral systems has been explained either by their ingestion of a higher quality grass (Hernandez et al., 2001, Iglesias, 1998) resulting from the inclusion of a legume in the system which provide N for grass growth or due to the intake of the legume itself, which in turn is also of higher quality than grass (Kakengi et al., 2001), and provides a higher microbial-N supply (Karda and Dryden, 2001). The objective of the present work was to discriminate, in a silvopastoral system, the effect of improved grass quality and legume intake (L. leucocephala) on rumen fermentation, microbial N supply, milk yield and composition of dual purpose lactating cows.