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The objective of this study was to evaluate the effect of the differentconcentration of DCBM on cow feed intake, production performence, digestion andmetabolism, rumen fermentation, and related bloodstream parameter through feedingdairy cows the DCBM, in order to give the proper dose.48healthy Holstein dairycows （lactation181days, milk production29.18kg/d, parity2.2） was randomlyassigned to4groups based on milk yield, milk days, the principles of the similarparity with each group of12cows.4kinds of different concentration of DCBM whichwas added to daily ration was0%,2.5%,5%,7.5%of dry matter weightrespectively.This study lasted74days with14days of preliminary period and60daysof trial period.1Effects of the DCBM on the production performance of dairy cowsCompared with the control group, lactose in milk of5%DCBM treatment groupin diet decreased significantly （P<0.01）, milk protein yield and milk protein contentwas significantly increased （P<0.05）; urea of2.5%DCBM treatment group wassignificantly decreased （P<0.05）; there was no significant impact on dry matter intake,milk yield, milk fat, lactose, non-fat solids and total solids yield （P>0.05）.2Effects of the DCBM on serum biochemical of dairy cowsAlbumin （ALB） of2.5%DCBM treatment group was significantly lower than theother three groups （P<0.05）,2.5%group globulin （GLB） was significantly higher than5%and7.5%DCBM treatment group （P<0.05）; alanine aminotransferase （ALP） of5%DCBM treatment group was significantly higher than the other three groups （P<0.05）; uric acid （UA） and urea nitrogen （UN） of7.5%DCBM treatment group wassignificantly lower than the other three groups （P<0.05）; compared with the controlgroup, there was no significant impact on blood leukocyte count, erythrocyte count,hematocrit, hemoglobin, platelet count, blood aspartate aminotransferase （AST）, totalprotein （TP）, albumin/globulin （A/G） and glucose （GLU） with different proportionsDCBM,（P>0.05）. however,Compared with the control group, globulin （GLB） in thetreatment groups with addition of DCBM had a tendency to increase （P>0.05）;butblood urea （UREA） levels were reduced by0.34%,0.12%and0.76%.3Effects of the DCBM on the rumen fermentation of dairy cows Compared with the control group, rumen pH values in the treatment group withaddition of DCBM were significantly decreased （P<0.05）, rumen microbial protein（MCP） was significantly increased （P<0.05）; NH3-N concentration and acetic acid/propionate ratio of5%DCBM treatment group was significantly lower or higherthan the other three groups （P<0.05）.but there was no significant impact on rumenacetic acid, propionic acid, acid and total volatile fatty acid concentrations （P>0.05）.4Effects of the DCBM on apparent nutrient digestibility of dairycowsCompared with the control group, digestibility of dry matter （DM）, organicmatter （OM）, crude protein（CP），neutral detergent fiber （NDF） and acid detergentfiber （ADF） were significantly lower in the control groups than those in other groups（P<0.05）.This shows that addition of DCBM in diets have a negative impact onapparent digestibility of nutrients.
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