Investigation of white-rot fungi for the conversion of poplar into a potential feedstuff for ruminants.

Five isolates of wood-rotting fungi were compared for their ability to increase the digestibility of poplar shavings. Homogenates of the fungi were inoculated into mixtures of 25 g of shavings and 100 mL of supplementary nutrient solution and incubated at 25 degrees C. The in vitro rumen digestibility of the products increased from 30% at the start of the fermentation to maxima of 72% with Polyporus anceps after 8 weeks, 64% with Ganoderma applanatum and 62% with Phanerochaete chrysosporium after 4 weeks, 61% with Polyporus versicolor after 3 weeks, and 42% with Fomitopsis ulmarius after 4 weeks. Fibre analysis showed a decrease in lignin as digestibility increased. Loss of carbohydrates occurred in all fermentations and continued after lignin loss ceased. Dry matter yield at the time of maximum digestibility ranged from 80 to 94% of the original dry matter. The highest digestibilities attained were similar to those of conventional roughage feeds for ruminants. This shows that this fermentation could form the basis of a practical system for converting poplar into a feedstuff.