QUALITY AND NUTRITIONAL VALUE OF SILAGES OF THREE SORGHUM (Sorghum bicolor L.) HYBRIDS HARVESTED IN DIFFERENT MATURATION STAGES

Abstract

Two dry stem intermediate height sorghum hybrids and a moist stem high height hybrid were ensiled in eight growing stages after bloom. Twenty four treatments were made with three repetitions each, being the three hybrids (AG2006 and BR700 – dry stem, and BR601 moist stem) ensiled in eight growing stages. Silages were evaluated for dry matter (DM), crude protein (CP), DM losses, silage density, pH, ammoniacal nitrogen (N-NH3), neutral detergent fiber (NDF), hemicellulose, cellulose and lignin, IVDMD and total phenols percentages. SNK test was used with a 3 x 8 random factorial design. DM production increased until fifth stage. DM values increased with growth and the best level occurred between 21st and 28th days after bloom. CP and fibrous fractions were reduced with growth. pH, N-NH3 and DM losses were low for all silages. Hybrids lignin and IVDMD varied in erratic ways. Silages were evaluated by Prussian blue assay to total phenols and tannins were detected in all of them. There were no negative correlations between tannins and IVDMD. AG2006 was better than the others two hybrids for some features, and IVDM of BR601, a forage sorghum, was better than BR700, an intermediate height sorghum.

Keywords

• animal nutrition
• ensiling: forage
• ruminants