Study On Assessment Technique Of The Absorbed Amino Acids Fluxes In The Small Intestine Of Common Feedstuffs For Dairy Cows

Carbohydrate and protein components of nineteen feeds were determined according tothe analysis methods provided by Cornell Net Carbohydrate and Protein System. The nylonbag technique was used to investigate the ruminal degradation rate of carbohydratecomponents and protein components. The regression equations of the feed components andruminal degradation rate of protein components were established. The database of absorbedamino acid fluxes in small intestine of feedstuff is established by CNCPS model. This study isdivided into the following three parts：1.nutritional value evaluation of common feedstuffs on diary cowsThe classification methods of CNCPS for nineteen feed protein and carbohydrate wereused for the analysis of CP, NPN, SCP, NDF, NDFIP,ADF, ADFIP, Starch and Lignin.PA, PB1,PB2,PB3and PC in the crude protein and CA,CB1,CB2and CC in the carbohydratewere calculated, respectively. Results showed NPN in corn silage,which contents above93%SCP,was highest among all feedstuffs.The carbohydrate of energy feedstuffs was higher,CB1carbohydrate component was significantly higher than other feedstuffs.The highest levelof unavailable fiber in cottonseed showed that the utilization of its carbohydrate was low.Thecontent of PA in protein of corn silage is higher,more than60%, showed that most of proteinin corn silage was NPN.2. Study on the rumen degradation rate of feed carbohydrate and protein componentsFour multiparous,ruminally cannulated Holstein dairy cows with similar milk productionperformance were used to evaluate rumen degradation rate of protein components andcarbohydrate components of nineteen feedstuff by using nylon bag method. Using the datafitting method to calculate rumen degradation rate of the protein components (PB1,PB2, PB3)and carbohydrate components (CA, CB1,CB2). Established the regression equation of therumen degradate rate of protein components and feed nutrient composition.Kd1=262.177-7.214NDIP(%CP)+6.570PB1-1.887CC(R2=0.7422,P<0.01,n=19) Kd2=4.721-0.188ADF+0.850Ash+0.226CA(R2=0.7365,P<0.01,n=19)Kd3=2.964+0.080Starch(R2=0.3871,P<0.01,n=19)The results show that rumen degradation rate of feed protein components and CNCPScomponents have good correlation. Rumen degradate rate of protein components can bepredicted by CNCPS components.3. Study on the absorbed essential amino acids fluxes in small intestine of common feedsAmino acid composition of rumen undegraded protein is equal to amino acidcomposition of insoluble protein in feedstuff in cornell net carbohydrate and protein system.In this experiment, amino acid content of insoluble protein in nineteen feedstuffs weremeasured to calculate the absorbed essential amino acids fluxes by using CNCPS model. Therumen degradate rate of protein fractions in CNCPS model was predicted according toregression relationship of feed nutrients. There was no significant difference betweenpredictive value of absorbed essential amino acids fluxes of the predicted model and CNCPSmodel.