Abstract: The activities of nonstarch polysaccharides hydrolases,including xylanase,β-glucanase and cellulase,in a premix enzyme preparation were assayed acurately by spectrophotometry.When the premipxreparation was added into feed at the ratio of 1:1000,the enzyme activities could not be determined individually with accuracy except for xylanase.Some inprovements of the assay methods were made as follows.Firstly,the enzyme solution was pretreated by gel filtration in order to remove fractions of low molecular weight,such as reducing sugar.Secondly,through the agar radial diffusion,the sensitivity and specificity of β-glucanase and cellase activity assay were improved greatly.In addition,the determining method of pectinase activity was changed to a more sensitive and specific one by using acidic copper acetate.Finally,through ammonium sulfate precipitation,the interference of other enzymes in xylanase activity bstractTheactivitiesofnonstarchpolysaccharideshydrolases,includingxylanase,β-glucanaseandcellulase,inapreassaywseliminated.

Key words: Nonstarchpolysaccharideshydrolases, Enzymeactivitydetermination