Fibrolytic potential of spent compost of the mushroom Agaricus bisporus to degrade forages for ruminants

To evaluate the fibrolytic potential to degrade forages, extracts from spent compost of Agaricus bisporus (SCAB) were evaluated in vitro. Firstly, SCAB was cultivated for 50, 60 and 90 days (culture stage) and enzyme activity was evaluated. The highest cellulase activity was at 60 days; xylanase activity was not affected by culture stage and laccase activity increased as culture stage increased. Secondly, extracts of SCAB cultivated for 60 days were preserved by refrigeration, freezing, freezedrying, refrigeration + benzoic acid, freezing + benzoic acid, freezing + glycerol, or freezing + benzoic acid-glycerol and then fibrolytic activity was evaluated. The highest fibrolytic activity was shown by SCAB frozen with addition of either glycerol or benzoic acid, or freeze-dried. Finally, effects of SCAB as an additive to enhance ruminal degradation of alfalfa hay, Taiwan grass, barley straw, and spent compost of A. bisporus were evaluated. Soluble fraction of dry matter of alfalfa and potential degradation of dry matter of Taiwan grass and barley straw were increased by SCAB. It is concluded that SCAB showed a noticeable fibrolytic activity which might increase degradation of forages in the rumen.