NUTRITIVE QUALITY OF TEN GRASSES DURING THE RAINY SEASON IN A HOT-HUMID CLIMATE AND ULTISOL SOIL

Abstract

The nutritive quality of ten grasses harvested at 3, 6, 9 and 12 weeks of regrowth was assessed during the rainy season (August-October) 2008, in the humid tropics of Veracruz, Mexico. Grasses tested included four Brachiaria spp.: “insurgenteâ€â€“B. brizantha, “signalâ€â€“B. decumbens, Chetumal–B. humidicola, “mulato Iâ€â€“B. brizantha x B. ruziziensis; three Panicum maximum: Mombasa, “privilegioâ€, Tanzania; and three Pennisetum spp.: Taiwán, and the hybrids P. purpureum x P. glaucum “Cuban†king grass and “purple†king grass. Means for crude protein by grass group were: Pennisetum spp. (9.9 %) = P. maximum (8.7 %) > Brachiaria spp. (7.6 %), whereas means for in situ dry matter disappearance (ISD) were: Pennisetum spp. (69.7 %) > Brachiaria spp. (65.1 %) > P. maximum (59.7 %). Crude protein and ISD significantly decreased by 0.42 % and 1.50 % per week. Neutral detergent fiber was not affected by model effects (mean 71.4 %). Means for acid detergent fiber (ADF) by grass group were: P. maximum (47.6 %) = Pennisetum spp. (44.0 %) > Brachiaria spp. (42.8 %), whereas means for lignin (LIG) were: P. maximum (8.5 %) > Pennisetum spp. (7.6 %) > Brachiaria spp. (6.7 %). The ADF and LIG significantly increased by 1.21 % and 0.19 % per week. Pennisetum spp. had the highest nutritive value at all regrowth ages.