The biodegradation of wheat straw by Pleurotus ostreatus mushrooms and its use in cattle feeding

The influence of Pleurotus ostreatus enzymes on wheat straw degradation was investigated in laboratory conditions. Chopped and pressure-pasteurized straw with 24% dry matter was seeded with mushroom mycelium. Analyses of the straw were done on day 15, 30, 45, 60, 90 and 120 after seeding. The mushroom collection was done four times. After seeding, NDF decreased from 824 to 485 g kg(-1), ADF from 561 to 412 g kg(-1). A similar tendency was found for hemicellulose and cellulose, while it was not so pronounced for lignin. Ash content increased from 62.6 to 97.8 g kg(-1). Degradation rates calculated for individual constituents of cell wall components were: hemicellulose 0.902, lignin 0.450, NDF 0.402, cellulose 0.290 and ADF 0.276% day(-1). The obtained results show that a substantial part of straw dry matter was degraded by the mushroom enzymes. The effects were most notable for cell-wall components which allowed successful use of the straw as a substrate for mushroom growth. It was assumed that spent Pleurotus compost may be used as a part of the cattle diet. That was investigated in a feeding trial where compost formed 0% (Control), 10% (Group I) and 17% (Group II) of dietary dry matter. It was found that animals would not consume mixed ration with more than 17% DM from compost. The decrease in daily gain was observed with the increase of compost level in the diet. Average daily gains were 1150, 1140 and 990 g day(-1) respectively. Animals in Group II had significantly lower gain compared with Control and Group I (P < 0.01). The utilization of dry matter per kg of gain had a tendency to decrease with the increased amount of compost in the diet. (C) 1998 Elsevier Science B.V.