Forage legumes included in diets with tropical grasses. II. Dry matter intake and nutrient digestibility

Abstract

The effects were determined of the inclusion of a legume (Leucaena leucocephala or Stylosanthes guianensis) at the rate of 10,20 or 40% of the dry matter, as a complement to tropical grass hay containing Cenchrus ciliaris L. and Dicanthium annulatum, on the dry matter intake (DMI), and on in vivo digestibility of the dry matter (DMD), neutral detergent fiber (NDFD), crude protein (CPD) and acid detergent fiber (ADFD). Dry matter and nutrient digestibility was measured with the total collection technique using lambs in individual pens. Dry matter intake was greater (P < 0.05) as the proportion of legume in the diets increased (1.00, 1.30 and 1.46% kg/d at 10, 20 and 40% of legume, respectively). Between the two legume species evaluated, DMI was greater in animals fed with Stylosanthes guianensis (1.30 kg/d) than ¡n animals fed with Leucaena leucocephala (1.16 kg/d). There were significant differences between the legume species in digestibility of the main feed components except crude protein. The mean values obtained for the diets with Leucaena leucocephala and Stylosanthes guianensis were DMD, 61.88 and 59.36; CPD, 71.37 and 70.26; NDFD, 62.57 and 58.33; and ADFD, 47.71 and 41.48%, respectively.There were no effects on digestibility when the legumes were added at 10 or 20% of the dry matter (means: DMD, 59.3; CPD, 70.5; NDFD, 59.1; and ADFD, 43.0%). However, when the legume constituted 40% of the dry matter, there was an increase in DMD (63.8%), NDFD (63.5%) and ADFD (48 6%), but not in CPD (71.1%). It is concluded that the utilization of legume species, as a complement to grass in diets for ruminants, can improve the productive performance because of increased intake of total digestible nutrients.