DETERMINATION OF METABOLIZABLE ENERGY OF SORGHUM SILAGE WITH DIFFERENT LEVELS OF FIBROLYTIC ENZYMES USING in vitro GAS PRODUCTION TECHNIQUE

This experiment was conducted to determine the fermentation characteristics and metabolizable energy (ME) of sorghum silage with different levels of fibrolytic enzymes using gas production technique. Three rumen fistulated Holstein steers were used in a complete random design with a 2 x 3 factorial arrangement of treatments to compare the additional time of enzyme (before or after ensiling) with three different levels of enzymes (3g, 6g and 9g) in sorghum silage. Experimental treatments were A: sorghum silage, B: sorghum + 3g fibrolytic enzymes before silage, C: sorghum + 6g fibrolytic enzymes before silage, D: sorghum + 9g fibrolytic enzymes before silage, E: sorghum + 3g fibrolytic enzymes after silage, F: sorghum + 6g fibrolytic enzymes after silage and G: sorghum + 9g fibrolytic enzymes after silage. Cumulative gas production was recorded at 2, 4, 6, 8, 12, 24, 48, 72 and 96 h of incubation also, and gas production parameters(b and c) were described using the equation y = b(1-e-ct). The result showed that enzymes decreased (P<0.05) the content of Neutral Detergent Fiber (NDF) and Acid Detergent Fiber (ADF) and increased (P>0.05) Crud Protein (CP), Ether Extract (EE) and Water Soluble Carbohydrate (WSC) in silage. The volume of gas production at each incubation time was higher in treatment G than the others. In treatment G, additional enzyme after ensiling caused a significant reduction in ADF and NDF content. The results showed that enzyme increased (b) fraction, but this increase was not significant in any of the treatments, that is probably due to the tannins in sorghum that prevents methane producing. Significant difference in fraction (c) was observed between the treatments. Gas production and ME were the highest (P<0.05) in G after 24h comparing to all other treatments. It was concluded, that silage and enzymes can be used in ruminants diets formulation.