| In this study,21 kinds of common forage of sheep as the research object,first according to the result of proximatenutrient analysis,the qualities of 21 kinds of forage were evaluated respectively by relative feed value(RFV)and forage grading index(GI),the rumen degradability of forage nutrient was determined by nylon bag method and intestinal digestibility of rumen undegraded feed residual was determined by mobile nylon bag method,based on the previous experimental results,intestinal digestible crude protein and dry matter digestibility of 21 kinds of forage were estimatedrespectively to provide the basic data for the supplement and perfection of Chinese feed ingredients and nutritional value database.Test1.Nutrient analysis and quality evaluation of common forage for sheep.According to the result of proximatenutrient analysis,the qualities of 21 kinds of forage were evaluated respectively by relative feed value and forage grading index,the results showed:(1)Except for the dry matter,there was a big difference between the nutritional components of the 21 kinds of forage,mean of CP,EE,CF,NFE,Ash,NDF,ADF was respectively 7.03%,1.96%,30.39%,40.69%,6.63%,63.19%,40.37%,and variation coefficient of CP,EE,CF,NFE,Ash,NDF,ADF was respectively 50.28%,69.98%,38.43%,26.85%,47.86%,17.96%,22.54%.(2)The results of GI2016 and GI2010 on forage quality evaluation were basically the same,according to the GI2016 can be divided into four grades of forage,apple leaves,alfalfa,ryegrass were ?-grade feed,millet bran,Chinese wildrye hay,willow leaf,sweet potato vine,apple pomace were ?-grade feed,silage sorgo,Coronilla varia,p.miliaceum straw,korshinsk peashrub were V-grade feed,rice bran,sorgo straw,silage corn,pine needle,corn straw,straw grass,rape grass,soy straw,wheat straw were VI-grade feed.Test2.The study on degradation characteristics of rumen of roughagenutrientin sheep.The test selected 4 one-year-old and non-pregnant Small Tail Han ewes with permanent rumenfistula,dry matter,crude protein,neutral detergent fiber and acid detergent fiber of 21 kinds of foragewere determined by using the nylon bag method to obtain rumen degradationrateat different time points.Thenaccording to the mathematical model,the rumen degradation kinetics of a,b,Kd and the effective degradation rate were calculated,the results showed:(1)During the period of 0~72h,the degradation rate of DM,CP,NDF and ADF of different kinds of forage increased gradually with the extension of the rumen fermentation time,and showed the regular pattern of "DM and CP>NDF>ADF",when the crude fiber content was lower(the feed quality is good),the DM degradation rate was greater than CP degradation rate,on the contrary,the CP degradation rate was greater than DM degradation rate.(2)The a,b,Kd and ED of DM,CP,NDF and ADF of 21 kinds of forage were significantly different(high variation coefficient),the EDCP was positively correlated with a(r=0.7942),EDDM,EDNDF showed low positive correlation with a(0.3<r<0.5),EDADF and a was not related(r=0.2010);EDDM,EDNDF,EDADF and b was significantlypositivecorrelated(correlation coefficient was about 0.65),but EDCP and b was lownegative correlated(r=-0.3971).(3)EDCP was not correlated with CP,CF,NDF and ADF(|r|<0.3);EDNDF and EDADF were not correlated with CP and NDF(|r| < 0.3),EDNDF and CF was significantly negativecorrelated(r=-0.5050),and was lownegativecorrelated with ADF(r=-0.4808),EDADF and CF,ADF were low negativecorrelation(correlation coefficient was respectively-0.4061 and-0.3396);EDDM was not correlated with CP(r= 0.2123),but negatively correlated with CF,NDF and ADF(0.5<|r|<0.8).Test3.The study on digestion characteristics of small intestine of roughagenutrientin sheep.The test selected 4 non-pregnant Small Tail Han ewes with permanent rumenfistula and 4 non-pregnant Small Tail Han ewes with permanent “T” type fistula,rumen undegraded dry matter(UDM)and crude protein(UDP)digestibility in small intestine of 21 kinds of forage were determined by using the mobile nylon bag method,the results showed:(1)Rumen undegraded dry matter digestibility in small intestine(IdgUDM)of 21 kinds of forage was great differences(mean was 9.75% and coefficient of variation was 77.56%),of which IdgUDMwas the highest in apple leaves(30.67%),apple pomace,willow leaf,respectively was 24.88%,21.59%,but wheat straw,soy straw was only 1.97%,2.20%.(2)Rumen undegraded protein digestibility in small intestine(IdgUDP)of 21 kinds of forage had great differences(mean was 35.41% and coefficient of variation was 42.48%),the highest IdgUDPwas 63.69% in ryegrass silage,alfalfa was second,millet bran was the lowest(9.27%).(3)In addition to apple pomace,20 kinds of forage showed a regularpatternof "IdgUDM<IdgUDP".(4)IdgUDP was not correlated with CP,CF,NDF and ADF(|r|<0.3),and was low positivecorrelation with EDCP(r= 0.338);IdgUDM was not correlated with CP and EDCP(|r|<0.3),but negatively correlated with CF,NDF and ADF(0.5<|r|<0.8),and had the highest correlation coefficient with NDF(r=-0.783),based on the above results,the unitary or multiple linear regression equation between IdgUDM and conventional nutrients and rumen effective degradation rate was established(P< 0.01).Test4.Evaluation of intestinedigestible crude protein and dry matter digestibility of forage.The small intestinal digestible crude protein and dry matter digestibility was estimated according to the rumen degradability and rumen undegraded dry matter and crude protein digestibility in small intestine of 21 kinds of forage,the results showed:(1)The intestinal digestible crude protein(IDCP)of 21 kinds of roughage had great difference(mean was 4.11% and coefficient of variation was 55.38%),the highest IDCP was 8.89% in alfalfa,ryegrass was second(8.20%),the lowest was wheat straw(1.23%).(2)IDCP/CP of 21 kinds of forage had relatively small difference(mean was 57.84% and coefficient of variation was 13.86%).(3)There was a big difference in dry matter digestibility(DMD)of 21 kinds of forage(mean was 53.32%and coefficient of variation was 22.64%),of which the highest DMD was 70.95% in apple leaves,followed by alfalfa(68.91%),and the lowest was 31.88% in caragana korshinskii.(4)The average contribution rate of IDCP produced after the digestion of UDP in the small intestine to total IDCP in the digestive tract was 21.93%,and the average contribution rate of DMD produced after the digestion of UDM in the small intestine to total DMD in the digestive tract was 8.66%.In summary,the following conclusions can be obtained through this study:(1)There was a big difference between the nutritional components of the 21 kinds of forage.(2)Crude protein degradation in rumen and rumen undegraded protein digestibility in small intestine with conventional nutrients were not related;the degradability of dry matter in rumen and rumen undegraded dry matter digestibility in small intestine were mainly affected by the content of fiber in the forage,and the higher the fiber content,the lower the degradation rate of DM and the small intestinal digestibility of UDM.(3)The digestion of CP and DM mainly occurred in the rumen,especially the digestion of DM.(4)The intestinal digestible crude protein content and dry matter digestibility of 21 kinds of forage had great difference respectively. |
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