不同品种紫花苜蓿青贮品质的差异及蛋白质二级结构变化的研究OA

The experiment was conducted to evaluate the silage quality and protein structure of five alfalfa(Medicago sativa L.)cultivars(Spreader,Beilin 201,WL298,Beilin 202,and Womu No.1)using wet chemistry analysis and spectroscopic techniques,so as to provide a reference for the scientific utiliza-tion of alfalfa.The results showed that after ensiling,Beilin 201 exhibited the highest lactic acid content(7.52%DM)and the lowest contents of ammonia nitrogen(1.18%DM),acetic acid(0.15%DM),and propionic acid(0.67%DM),while no butyric acid was detected in any treatments.The crude protein(CP)content of all cultivars exceeded 21.84%,with Beilin 201 being the highest.The in vitro dry matter digest-ibility(IVDMD)of Spyder was significantly higher than that of the other cultivars,and WL298 had the highest in vitro crude protein digestibility(IVCPD).Protein secondary structure analysis revealed that after ensiling,the β-sheet content increased,whereas the contents of random coil,α-helix,and β-turn decreased.Beilin 201,Beilin 202,and WL 298 displayed higher random coil contents than Womu No.1,while the β-turn content showed an opposite trend.Redundancy analysis(RDA)indicated that β-sheet was negatively correlated with soluble protein(SP)and IVCPD,whereas random coil,α-helix,and β-turn were positively correlated with SP.In conclusion,cultivar has a significant effect on the silage quality and pro-tein secondary structure of alfalfa.Beilin 201 exhibited superior silage quality,characterized by the highest lactic acid and crude protein contents and the lowest ammonia nitrogen content.The ensiling process induced marked changes in protein secondary structure,with the β-sheet proportion increasing substantially to become the dominant conformation.These findings provide a theoretical basis for exploring quality changes in silage from the perspective of protein structure.