The nutritive value of five sorghum hybrids (AG-2002, AG-2005E, AG-X202, AG-X213 and AG-X215) silages, cultivated under increasing fertilization levels (control, 0.5, 1.0, and 2.0 times of the recommended fertilization, corresponding to 0, 45.5, 91, and 182 kg/ha N; 0, 49, 98, and 196 kg/ha de P2O5; and 0, 14, 28, and 56 kg/ha de K2O, besides of 0, 42, 84, and 168 kg/ha S, respectively, that came from the used ammonia sulfate). A complete randomized block design in a factorial 5x4 arrangement (five hybrids and four fertilization levels) with four replicates was used. The seeding time was at 11.06.1997 and plots were harvested at the soft dough stage of grain. From each plot, a sample was collected to fill up the experimental silos, which were opened after 60 days and sampled again to determine the pre drying weight and the nutritive value (CP, fiber fractions and IVDMD). Data were interpreted by means of analysis of variance and regression. The hybrid x fertilizer interaction was unrolled independently of its significance. The qualitative factor means were compared by Tukey test. The models were chosen based on regression coefficients significance, using Student "t" test, at 10% level, and on the determination coefficient. The silages nutritive value differed among the hybrids. AG2005E showed the highest nutritive value, whereas AG2002 and AGX213 showed the highest nutrient yield per unit of area. The fertilizers affected the silages nutritive value, but, inconsistently
fertilization; nutritive value; silage; sorghum
