Caracteristicas agronomicas y nutricionales de asociaciones de gramineas y leguminosas tropicales

Two experiments were conducted. The objective of the first was to compare voluntary intake and digestibility of dry matter (DM), crude protein (CP) and neutral detergent fiber (NDF) of guinea grass-clitoria mixed hay (GCH; 33:67%) and of rhodesgrass hay (RGH). Ten adult creole rams (35 kg liveweight) were stratified by weight and assigned to the hays under evaluation according to a "crossover experimental design". Higher voluntary intake (P<0.05) was observed in rams fed GCH than RGH (919 vs. 669 g/d). Digestibilities of dry matter (65.2 vs. 55.51%) and CP (78.8 vs. 65.2%) were higher (P<0.05) in GCH than in RGH. However, NDF digestibility of GCH (58.3%) and RGH (53.9%) did not differ (P>0.05). Feeding GCH resulted in a 27% relative increase in intake with respect to RGH. In conclusion, GCH is a promising alternative for use in the feeding of ruminants.;The second experiment consisted of two plantings of maize (Zea mays cv. Mayorbela), the first in September 2005 and the second in February 2006, to determine the effects of interplanting mucuna ( Mucuna pruriens L. cv. Vine 90 days) at different time intervals (maize-mucuna at day 0; maize-mucuna at day 7; maize-mucuna at day 14; maize-mucuna at day 21 and a control of maize in monoculture). The variables evaluated were botanical composition (maize, mucuna and weed proportions); chemical composition [CP, NDF and acid detergent fiber (ADF)]; silage fermentative characteristics (pH and organic acids); and aerobic stability of the silage at 45 days after ensiling. For the maize component (7.51 and 12 t DM/ha) and total vegetable yield (11.07 and 14.59 t DM/ha) greater DM yields (P<0.05) were observed at the second planting. By contrast the components mucuna (2.96 and 1.67 t DM/ha) and weeds (0.58 and 0.07 t DM/ha) had greater DM yields (P<0.05) at the first planting. The forage proportion constituted by the mucuna interplanted with maize was 34%, at 0 day, but when intercalated at 7, 14 and 21 days, it contributed 24, 18 and 10%, respectively. Neither the total forage yield, nor the maize DM yield was affected by the interplanting method. The highest (P<0.05) CP content of total forage was observed with mucuna intercalated with maize at 0 and 7 days at both the first (10 and 9.3%), and second plantings (7.43 and 6.84%). These treatments gave CP contents 2 points higher than mucuna interplanted at 14 and 21 days, and 4 points higher compared to maize alone. This result was due to the greater proportions of mucuna founded in the resultant fodder when mucuna was interplanted with maize at 0 and 7 days. Concentrations of NDF and ADF were lower with interplanting at 0 and 7 days compared to maize monoculture. Mucuna interplanting had no effect (P>0.05) on pH and acetic and lactic acid concentrations of the silage, nor did it prevent deterioration of the silage upon aerobic exposure. In conclusion, the interplanting of mucuna in previously seeded maize 0 or 7 days later improves yield and nutritive value of the forage, and permits production of good silage, thus it constitutes an alternative for use in feeding systems for milk production in Puerto Rico.