In a wider range of fibrolytic enzyme
preparations, those with endo-(β-1,4)- or exo-(β-1,4)-xylanase
activity equal to that of preparation A did not
produce similar increased rates of fermentation of corn
silage when glucanase activity was low (P > 0.05). In
contrast, preparations with glucanase activity similar
to enzymeA gave at least as great (P < 0.05) an improvement
in gas production than enzyme A, irrespective of
xylanase activity. It was concluded that enzyme activity,
probably a type of endo-(β-1,4)-glucanase activity,
limits the rate of fermentation of corn and grass silage
in the rumen. Enzyme supplements of the type used
in these experiments are unlikely to possess sufficient
activity to overcome this limitation by direct application
to ruminal digesta, implying that treatment of the
ration prefeeding will be key to harnessing the potential
of exogenous fibrolytic enzymes in ruminant nutrition