The Study On Protein And Fiber Degradability Of Main Feeds In Rumen Of Dairy Cows

Three experments are carried out to complete the study. Three good physical condition China Hesitan cows weighting about 550 kg and installed permanent rumen fistula were chosen for experiment 1. Co—EDTA and Cr2O3 were used as markers in order to determine the liquid diluted rate and solid passage rate of ruminal contents of dairy cows.The results showed that the liquid diluted rate,rumen volume and liquid outflow rate are 11.15±1.23(%/h),70.85±9.97(L) and 7.85±0.93(L/h) respectively; the solid passage rate of the rumen and rectum are respectively 3.87±0.23(%/h) and 4.11±0.087(%/h);The regression equation of solid passage rate in rumen(Yr) and solid passage rate in rectum(Xf) is : Yr = 2.3553 Xf - 5.8135,R2 = 0.8326,P=0.27。Three Hesitan cows fitted permanent rumen fistula were selected to estimate the dynamic degradability and effective degradation rate in rumen of protein,NDF and ADF of main feeds by nylon bag technique for experiment 2 and experiment 3. The results are as follows:1. Among all protein feeds, the effective degradation rate of CP,DM,NDF and ADF of soybean meal are all higher,which are 61.09%,55.79%,50.74% and 30.73% respectively. The ones of corn gluten meal are lower the soybean's,which are 44.94%,46.76%,47.03% respectively. The effective degradation rate of protein in sunflower meal is 61.17%, which is the highest in all protein feeds; the one of cotton seed meal is about 50%, which is higher among all protein feeds; the one of lees meal is the lowest, which is lower than 20%; the others'are all lower than 35%(19%～34%). The effective degradation rates of dry matter of sunflower,sesame cake and meal,cotton seed meal,rape seed meal,ricinus communis meal and lees meal are all between 32%～41%; The effective degradation rates of NDF and ADF are lower than 20% mostly.2. Among all grains and brans, the effective degradation rate of protein of corn is 31.80%. The effective degradation rate of CP,DM,NDF and ADF of wheat bran 52.72%,71.48%,40.48% and 24.51% respectively; the ones of corn bran and vermicelli bran are lower than wheat bran's;the ones of rice bran and millet bran are much lower, especially NDF and ADF which scarcely degrade in rumen.3. Among all roughages, the effective degradation rate of CP,DM,NDF and ADF of alfalfa and alfalfa clump are 51.23% and 51.43%, 55.01% and 52.82%, 36.05% and 28.7%, 39.77% and 30.44% respectively,which are higher than other roughages'; The ones of leymus chinensis and smooth bromegrass are lower than alfalfa's at various degrees, especially the effective degradation rate of protein of leymus chinensis which is lower than 20%. The effective degradation rate of CP and DM of yellow corn silage and corn silage are higher than corn strow's significantly. The difference among the effective degradation rate of NDF and ADF of corn strow,corn silage and yellow corn silage is much small.4. The effective degradation rate of protein presented lepto- positive correlation with repid degradation part ,which tendency significant(r=0.36754,p=0.0647); it presents extreme significantly mid- positive correlation with slow degradation part(r=0.50129,p=0.0091). The effective degradation rate of feeds'NDF or ADF presents extreme significantly elev- positive correlation with thire repid degradation part(r=0.80742,p<0.0001;r=0.85009,p<0.0001),but they scarcely have correlation with thire slow degradation part.