Effects Of Different Faba Bean Varieties And Heat Treatment On Protein Structure And Nutritional Characteristics Of Rumen Degradation Residues In Western Canada

There is little or no relevant data and information on the protein molecular structure spectral parameters and nutritional utilization and metabolism of faba bean seeds,especially for faba beans of western Canada genotype.The purpose of this study was to investigate the effects of different genotype faba bean seeds and different heat treatments on the molecular structure of faba bean protein using attenuated total reflection Fourier transform infrared spectroscopy(ATR-Ft/IRS).This study can lay the foundation for future ruminant nutrition research.Experiment 1:ATR-Ft/IRS was used to determine the peak heights,areas and their ratios of amideⅠ,amideⅡ,α-helix andβ-sheet of faba bean seeds after rumen degradation of different varieties and at different times.The area and ratio were used to systematically compare the effects of different genotypes of faba bean varieties on the intrinsic molecular structure of their proteins.The results showed that:(1)After degradation by the rumen,the protein molecular spectral parameter values of faba bean genotypes with normal tannin levels were greater than those of faba bean genotypes with low tannin levels(P<0.05).(2)Except for the Snowdrop genotype,the peak height and peak area of the protein molecular structure of all other genotype broad bean seeds first increased and then decreased with the degradation time.(3)Changes in the molecular structure of proteins caused by different genotype faba bean seeds and different rumen degradation times were less predictive of the intestinal digestibility of crude protein,rumen degradation kinetic parameters,rumen degraded protein,and intestinal digestibility of rumen bypass protein(dIDP).(4)After 8 hours of rumen degradation,the molecular structure of proteins of different genotypes had the highest correlation with dIDP.(5)After 12h and 24h degradation by the rumen,the molecular spectral parameters of faba bean seed residues in the infrared fingerprint region were not clustered,but were hybridized with each other,indicating that they had similar protein molecular structures after rumen degradation.Summary:There was a relationship between the molecular structures of protein in faba bean seeds after rumen degradation and the nutritional characteristics of normal and low tannin level of faba bean seeds.Faba seeds of different genotypes had an effect on the molecular structure of the protein,but the molecular structure of the infrared spectrum of its protein was less predictable for protein utilization and metabolism.Experiment 2:The purpose of this study was to evaluate the effect of heating process on the molecular structure of protein in faba bean seeds after rumen degradation,and to analyze its intestinal digestibility with crude protein,rumen degradation kinetic parameters,rumen degraded protein,and dIDP contact.The results showed that:(1)steam heating increased the spectral parameter values of amide I,amide II,α-helix andβ-sheet,but it reduced the peak heights,areas and their ratios of amide I and amide II,and theα-helix and the peak height ratio ofβ-sheet began to decrease after 12h from rumen degradation.(2)All spectral parameter values and ratios of amide I,amide II,α-helix andβ-sheet reduced by microwave heating.However,the ratio of the peak area of amide I to amide II decreased from 24 hours of rumen degradation.(3)The spectrum parameters of amide I,amide II,α-helix andβ-sheet of steam-heated broad bean seeds increased first and then decreased with the increase of rumen degradation time.The peak heights,areas and their ratios of the amide II region,and the peak height ratio of theα-helix andβ-sheet always decreased.This condition was not observed with microwave-heated broad bean seeds,and its spectral parameter values remained essentially unchanged with rumen degradation time.(4)Rumen protein degradation parameter values including rumen bypass crude protein and rumen degraded proteins,which were closely related to peak height,peak area,and their ratios.(5)Soluble fraction(S,R~2=0.79),degradation fraction(D,R~2=0.805),rumen bypass crude protein(BCP,R~2=0.941)and rumen-degradable protein(RDP,R~2=0.811)of linear regression analysis showed better predictive power.Summary:The heat-induced changes in protein molecular structure were closely related to crude protein,rumen degradation kinetic parameters,and rumen-degraded protein and intestinal digestibility of rumen-degraded protein.In summary,the ATR-Ft/IRS could be used as a predictive technology for dairy nutrition utilization in dairy cows with lower cost,shorter time,less invasiveness and simple method.It is of great significance to formulate feed formula,breeding plan,predict feed quality,and formulate correct processing technology.