Changed Molecular Structures Of Extruded And Fermented Soybean Based On FTIR And Their Effects On Rumen Degradation

Chemical,physical and biological treatment will change the nutritional value of the feed,which is reflected in the changes of in situ rumen degradation.Traditional methods of evaluating feed nutrition value are based on chemical analysis and no molecular structures of feed were explored.However,the feed nutritional value is closely related to the molecular structures.In this study,the nutritional value of extruded and fermented soybean products was studied by traditional chemical methods and Fourier transform infrared spectroscopy?FTIR?and established the relationship between the rumen degradation of nutrition components and their molecular structures,which laid a foundation for the study of the relationship between molecular structures and feed nutrition value.This experiment choosed five soybean products,their processing methods are as follows:Soybean meal 1,Tieling 93,crude protein content is 43%,softened at 60⁶5?-breaked-tableted-extractded-dried and packed at 100¹25?;soybean meal 2,Changchun 93,crude protein content is 43%,softened at 60⁶5?-breaked-tableted-extracted-dried and packed at 100¹25?;extruded soybean meal,softened at 60⁶5?-breaked-tableted-extracted-extruded at 100¹05?-dried and packed at 100¹25?;fermented soybean meal,soybean meal 1 or soybean meal 2 was choosed and fermented with lactobacillus acidophilus and saccharomyces cerevisiae at 15²0?for 1³ days with water content at 65⁷5%;extruded soybean,whole soybeans were extruded with dry extruding using extruder at 135¹45?,then the soybeans were squirted out quickly because of high temperature and high pressure inside the extruder.The experiments included determination of nutrients and CNCPS components;degradation of dry matter,protein,neutral detergent fiber and acid detergent fiber in the rumen by nylon bag method,molecular structures of protein and carbohydrate were analyzed by Fourier transform infrared spectroscopy?FTIR?.The results were as follows:?1?Extruding and fermentation reduced the content of neutral detergent fiber,acid detergent fiber and lignin.Fermentation increased the content of crude protein and soluble protein.?2?Compared with soybean meal 1 and soybean meal 2,extruding and fermentation significantly reduced the related protein intensity of the spectra?height and area of amide I and amide II,height of?-helix and?-sheet?and the greatest reduction was found in extruded soybean.The ratio of spectral values were also significantly different?P<0.05?.The area ratio of amide I to amide II and height ration of?-helix to?-sheet in extruded soybean decreased significantly,but there was no significant difference between extruded soybean meal and fermented soybean meal.?3?Compared with soybean meal 1 and soybean meal 2,extruding and fermentation decreased significantly the spectra intensity of carbohydrate?P<0.05?.the spectra values of STCHO and CELC of extruded soybean meal and fermented soybean meal were not significantly different except STCHO peak 3 height.However,the spectral values of STCHO and CELC of extruded soybean were significantly reduced comparing with extruded soybean meal and fermented soybean meal.In addition,the peak area of CHO in fermented soybean meal was significantly reduced and was also the lowest in five samples.?4?The correlations between molecular strutures and in situ in situ rumen degradation showed that dry matter and crude protein in situ rumen degradation were affected not only by protein but carbohydrate structures.A-CELC/A-CHO and H₂ were better index to predict dry matter rumen effective digestibility?R²=0.8698,P<0.0001?.A-CELC/A-CHO,A-CHO,A-STCHO and S₂H were better index to predict protein rumen effective digestibility?R²=0.9795,P<0.0001?and A-CHO could be used to predict NDF and ADF rumen effective digestibility?R²=0.3796,P=0.0117;R²=0.5145,P=0.0026?.Extruding and fermentation would change soybean products molecular strutures and there is a relationship between molecular strutures and soybean products nutritional value.FTIR technology could be used to analyse molecular strutures of protein and carbohydrate and evalute feed nutritional value.