Forage sorghum silages with different tannin concentrations and moist stem or not. IV - In vitro dry matter digestibility

Four hybrid forage sorghums with different tannin concentrations and moist stem or not were ensiled in laboratory silos made of "PVC" tubes, which were opened after 1 (P2), 7 (P3), 14 (P4), 28 (P5) and 56 (P6) days, in order to evaluate fermentation patterns and other parameters. Twenty four treatments were made, with four replications each: four hybrids (H1=high tannin/moist stem, H2=low tannin/not moist stem, H3=high tannin/not moist stem, N4=low tannin/moist stem) and six periods, since the forages before ensilage (PI) were also studied. Tannin concentrations and in vitro dry matter digestibility (IVDMD) were determined. Data were evaluated by analysis of variance, with mean separation achieved using SNK statistical test, with a 4x6 factorial scheme. Tannin concentration reduced as silage fermentation developed, although the IVDMD did nor increase.