NUTRITIONAL PARAMETERS OF SILAGE FROM FOUR SORGHUM HYBRIDS SUBMITTED TO INCREA-SING NITROGEN DOSES

Abstract

The objective of this study was to evaluate the nu-tritional parameters of silage from four forage sorghum cultivars submitted to three nitrogen rates. A randomized block experimental design was used, arranged as a 4×3 fac-torial combination (four cultivars × three nitrogen rates), with four replicates. The following cultivars were used: 1F 305; 0369 267; 0369 255; and BR 700. Nitrogen rates were: 0; 60; and 120 Kg N.ha-1 (in the form of ammonium sulfate). Tukey test (5%) was used to compare means. DM contents were different (P<0.05) between cultivars 1F 305 and 069 267, with variations from 26.23 to 29.57%. DM contents differed between the rates of 60 and 120 kg.ha-1, with means of 27.77 and 27.90% due to the treatments. NDF contents were different (P<0.05) between cultivars 1F 305 and 0369 267, with a general variation from 49.62 to 59.69%. In the same way, ADF contents were only di-fferent between cultivars 1F 305 and 0369 267, with a general variation from 229.62 to 34.68%. kg.ha-1. ADF values had the same behavior, with an overall mean of 31.69%. Hemicellulose concentration ranged from 22.53 to 23.31%; Cellulose ranged from 24.22 to 24.48%, and Lignin ranged from 6.37 to 6.46%. CP contents were di-fferent (P<0.05) between cultivars 1F 305 and 0369 267, with a general variation from 6.23 to 7.53%. Crude protein content differed between the rates of 60 and 120 kg.ha-1, with means of 6.80% (control), 6.84, and 6.91%, respecti-vely. IVDMD values did not differ (P>0.05) between cul-tivars and N rates, with means of 46.54% (control), 49.60, and 50.07% obtained with the application of 60 and 120 kg.ha-1 N, respectively. The evaluated cultivars demons-trated good chemical composition, providing good IVD-MD in the silages produced.

KEY-WORDS: Chemical composition, nitrogen fertilization, nutritional value.