Nutritional Evaluation of Wheat Straw Incubated with the Edible Mushroom, Pleurotus Ostreatus

Abstract

Studies were conducted to evaluate culturing of the edible mushroom Pleurotus ostreatus and the bacterium Erwinia carotovora on wheat straw as a means of improving the nutritive value of straw for ruminant animals. In vitro dry matter digestibility (IVDMD) of the straw was not improved (P>.05) by incubating the straw with P. ostreatus alone. However, 56-d incubations at 50% dry matter (DM) with P. ostreatus and E. carotovora increased (P<.05) IVDMD from 32.7 to 47.7%. Preheating or autoclaving the straw before inoculation was found not to be necessary. The IVDMD of the straw was improved more consistently when the straw was incubated at 50% DM rather than at 33 or 25% DM. DM decomposition of the straw ranged from 28.8 to 55.9%. Neither particle size nor substrate to inoculum ratio affected (P>.05) IVDMD. Lignin decomposition of 10 g of straw preheated at 25 C and incubated at 25 C and 50% DM for 56 d was 69%, which was intermediate to that of hemicellulose, at 83%, and cellulose, at 55%. It is believed that such biodelignification and the concurrent 15-percentage unit increase in IVDMD indicate that the culturing of P. ostreatus and E. carotovora on straw may, in fact, improve the straw’s nutritive value for ruminant animals.