Influence of fibrolytic enzymes on in vitro methane production and rumen fermentation of a substrate containing 60 per cent of grass hay
2007
Giraldo, L.A.; Carro, M.D.; Ranilla, M.J.; Tejido, M.L., Universidad de León (Spain). Departamento de Producción Animal I | Giraldo, L.A., Universidad Nacional de Colombia, Sede Medellín (Colombia). Facultad de Ciencias Agropecuarias
Batch cultures of mixed rumen microorganisms were used to study the effects of exogenous fibrolytic enzymes on the in vitro fermentation of a substrate composed by a 60:40 mixture of grass hay and concentrate. Three enzymatic preparations were tested: cellulase from Aspergillus niger (CEL), xylanase from Trichoderma viride (XYL), and a 1:1 mixture cellulase:xylanase (MIX). Samples of substrate were accurately weighed into 120-ml serum bottles and enzymes were added directly into the bottles at three levels: 0 (control; CON), 15 (-15) and 30 (-30) IU per g substrate DM. Bottles were kept at room temperature for 24 h before incubation with buffered rumen fluid. All enzymatic treatments, with the exception of CEL-15, increased CH4 production after 6 h of incubation, but after 24 h of incubation differences with control were only detected for XYL-15, XYL-30 and MIX-30. Acetate, propionate and butyrate productions at both 6 and 24 h of incubation were increased by all enzymatic treatments. NH3-N concentrations, pH and gas production at 24 h of incubation were not affected by the addition of enzymes. The treatment of substrate with XYL-15, MIX-15 and MIX-30 increased neutral-detergent fibre degradability compared to the control. The results indicate that the xylanase was more effective than the cellulase in stimulating the in vitro fermentation of substrate, but for most of the measured parameters there were no differences due to the level of enzymes
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