The effects of a product of the solid-state fermentation of Aspergillus niger on the in vitro rumen fermentation kinetics of rations fed to dairy cattle

The aim of this study was to determine the effects of incubating different doses of Synergen® (0, 0.5, 2, 5 mg/g substrate), a product of the solid-state fermentation of Aspergillus niger (ANP) containing residual enzyme activities, with two total mixed rations (TMR) formulated for dairy cattle, on the kinetics and end products of in vitro rumen fermentation. The inclusion of fungal fermentation products in cattle rations has improved digestibility measures and production performance and, may offer an avenue to improve the sustainability of ruminant production. In this study, a dose-responsive effect was observed for gas production from a high starch TMR over a 72-h incubation; doses of 2 and 5 mg ANP/g substrate significantly increased gas production by 33 ml (P = 0.024) and 32.9 ml (P = 0.025), respectively, compared to controls. However, no effect of treatment was observed on volatile fatty acid composition at the end of incubations. ANP treatment had no effect on the fermentation kinetics of a low starch TMR, suggesting that the dominant effect of treatment was amylolytic. Further research into the effects of ANP in cattle models is required to explore the utility of the product on farm.