In sacco degradability of straw treated with cellulolytic enzymes containing fermented substrates

Abstract

Four fungi varieties (Wild variety, Chaetomium cellulolyticum, Trichoderma harzianum and Penicillium colony 10) were cultivated in a solid‐state fermentation on a wheat straw‐wheat bran‐sugar beet pulp mixture (20 : 40: 40%).

The fermented substrates contained xylanase (22.1 to 78.6 Units g^‐1 DM) and cellulase (0.47 to 14.0 Units g^‐1 DM). Fermented substrate was homogeneously mixed with ground wheat straw (1: 2; 1: 5 and 1 : 10), moistened to 30 or 50% DM, airtightly stored for 24 h at 50°C and deep frozen. All samples were given in nylon bags and incubated for 48 h in the rumen of 4 sheep.

In sacco DMD decreased with higher straw proportions in the mixture (1: 2; 1 : 5 and 1: 10: 52.0; 46.8 and 44.2% resp.), the DM‐content did not significantly influence the in sacco DMD. The Wild variety and Chaetomium cellulolyticum did not significantly influence the in sacco DMD, Trichoderma harzianum and Penicillium colony 10 decreased DMD in some cases.

In general added fungi did not improve the rumen degradability of fibre.

Key words:

• Solid state fermentation
• Fungi
• Cellulolytical enzymes
• Wheat straw
• In sacco degradability
• Sheep