Relationship Of Nutrients In Alfalfa With Molecular Structure And Lignin Content

The purpose of this trial was to investigate the correlation between the internal molecular structure parameters of alfalfa and its ruminal degradation characteristics,and to establish a regression equation for predicting rumen digestion parameters.The leaf blades,lateral stems,upper stems,lower stems,and whole plants of the alfalfa plants isolated by freehand were selected as study objects.Conventional chemical analysis methods were used to determine their nutritional content,ruminal degradation parameters of dry matter(DM),crude protein(CP)and neutral detergent fiber(NDF)were measured by nylon bag method.At the same time,Fourier transform infrared spectroscopy(FTIR)analysis techniques were used to determine their protein and carbohydrate molecular structure.It lay a foundation for the rapid and accurate determination of rumen degradation parameters.(1)The leaves'contents of protein nutrients(such as crude protein(CP),soluble protein(SCP),etc.)were the highest,and insoluble carbohydrate components of the lower stem(such as acid detergent lignin(ADL),cellulose were the highest,in all parts of the alfalfa.Combining the rumen degradation parameters at different parts,the highest nutritional value of the leaves is known.(2)The protein molecular structure and the carbohydrate molecular structure parameters were different in different parts of the alfalfa.Leaf values are significantly higher than other parts(except for the peak height ratios of the Amide I band and the Amide II band)in protein-related molecular structures;In the carbohydrate-related molecular structure,the total fiber area(CELC),structural carbohydrate area(STCHO),and total carbohydrate area(CHO)of the lower stem were significantly higher than those of other parts,which were closely related to the conventional nutrient content of the feed itself and its degradation characteristics in the rumen.(3)According to the correlation analysis,the rumen degradation parameters of DM are not only related to the molecular structure of the protein,but also related to the molecular structure parameters of carbohydrates.By regression analysis,the peak height of?-helix,the peak height ratio of amide I and II bands and the lignin content were all screened as predictors of the effective degradation rate of CP(R~2=0.97,P<0.01).The ratio of fiber composite peak area(CELC)to total carbohydrate area(CHO),amide II band peak area,and lignin content were the predictors of the effective degradation rate of DM(R~2=0.99,P<0.01).The ratio of the peak area of the fibrous composite(CELC)to the total carbohydrate peak area(CHO)and the carbohydrate peak height ratio h1:h2 were selected as the factors in the prediction model of the effective degradation rate of NDF(R~2=0.97,P<0.01).