BIOMASS PRODUCTION WITH ELEPHANT GRASS (PENNISETUM-PURPUREUM) AND SUGAR-CANE (SACCHARUM-OFFICINARUM) FOR TROPICAL LIVESTOCK PRODUCTION .2. SOLUBLE AND STRUCTURAL CARBOHYDRATES

Soluble and structural carbohydrate performance of elephant grass clon es (Pennisetum purpureum) CUBA CT 115, CUBA CT 169 and king grass cut 2, 4 and 5 times a year with sugar cane (Saccharum officinarum) variet ies Jaronu 60-5 and clone 21 cut once and twice a year were analysed f or 5 years in a random block design with 5 replications. Significant d ifferences were found for acid detergent fibre of leaves, stems and th e whole plant, the lowest values (P < 0.001) for the latter were found in Pennisetum clones (42.31-42.92%) cut five times a year. Significan t differences were also encountered for cell walls of leaves and stems and the greatest amount (P < 0.001) was in the whole king grass plant (78.79%) cut four times a year. The content of lignin in leaves and s tems showed significant differences (8.66-14.68%), but the highest acc umulation was observed in the whole king grass plant (13.82%) cut twic e a year. Cellulose also offered significant differences in CUBA CT 16 9 (44.64%) cut twice a year and no differences were found for king gra ss (45.37%) and CUBA CT 169 (46.26%) cut four times a year. The conten t of hemicellulose tended to decrease as the cutting frequency was red uced. The highest (P < 0.001) percentage of soluble carbohydrates in a lcohol was obtained in the leaves (6.95%), stems (52.13%) and the whol e plant (47.31%) of Jaronu sugar cane cut once a year. A variation for total water soluble carbohydrates was observed in the leaves (7.42%), stems (54.70%) and whole plant (49.80%) of Jaronu cut once a year. Th e variation produced by the cutting frequency on soluble and structura l carbohydrates of the species studied is discussed.