Effect of Aspergillus oryzae Fermentation Extract (Amaferm®) on In Vitro Fiber Degradation

Abstract

The influence of Aspergillus oryzae fermentation extract (Amaferm®) on in vitro fiber degradation was determined by incubating eight ground fibrous feedstuffs with rumen fluid and buffer inoculum. Amaferm® was added at 0, .4, .8, or 1.2g/L of fermentation mixture. Both NDF and ADF degradabilities were determined after 96h of incubation. Addition of extract had no effect on NDF or ADF degradability of pure cellulose, low endophyte fescue, wheat straw, corn silage, or prairie hay. Addition of Amaferm® at .8 or 1.2g/L increased NDF and ADF degradations of bromegrass hay and alfalfa hay; its addition at .4 or .8g/L, but not at 1.2g/L increased NDF and ADF degradation of high endophyte fescue hay. In a second set of in vitro fermentations, selective antimicrobials (penicillin, streptomycin, and cycloheximide) were used to assess the influence of Amaferm® on various microbial groups. The enhanced fiber degradation by Amaferm® was attributed to its stimulation of bacterial activity because its addition to whole rumen fluid without or with cycloheximide increased fiber digestion. In contrast, addition of Amaferm® to the whole rumen fluid plus penicillin and streptomycin treatment had no effect on fiber degradation, suggesting that fungal or protozoal activity was not affected by treatment. In conclusion, Amaferm® increased fiber digestibility of certain feedstuffs, and the increase was mediated via stimulation of rumen bacterial, but not fungal or protozoal activities.