不同种植地全株青贮玉米蛋白质营养价值及瘤胃降解特性与其分子结构之间的关系

Relationship between Protein Nutrition Value,Rumen Degradation Characteristics and Its Molecular Structure of Whole Silage Corn in Different Producing Areas

本试验旨在探究不同种植地对全株青贮玉米蛋白质分子结构的影响及其与蛋白质营养价值、瘤胃降解特性之间的相关关系。本试验采用常规化学分析方法、美国康奈尔大学净碳水化合物-净蛋白质体系(CNCPS)、尼龙袋技术对不同种植地的全株青贮玉米营养价值进行评定,并结合傅里叶变换红外光谱(FTIR)技术对青贮玉米蛋白质分子结构进行研究,进而探求蛋白质分子结构与蛋白质营养价值之间的相关关系。结果表明:1)不同种植地全株青贮玉米蛋白质化学成分存在显著差异(P<0.05);CNCPS蛋白质组分中非蛋白氮、中速降解蛋白、慢速降解蛋白、不可利用蛋白含量存在显著差异(P<0.05);干物质及粗蛋白质有效降解率也存在显著差异(P<0.05)。2)通过FTIR扫描后发现,不同种植地对全株青贮玉米蛋白质分子结构中酰胺Ⅰ带的峰高、峰面积,酰胺Ⅱ带的峰高、峰面积,酰胺Ⅰ带与Ⅱ带的总峰面积、峰面积比、峰高比,α-螺旋、β-折叠峰高均有显著影响(P<0.05)。3)酰胺Ⅰ带峰高、峰面积,酰胺Ⅱ带峰高、峰面积,酰胺Ⅰ带与Ⅱ带峰高比、峰面积比以及α-螺旋峰高均可以作为预测因子对全株青贮玉米蛋白质营养价值及瘤胃降解参数进行预测。其中,青贮玉米蛋白质分子结构对粗蛋白质(R^2=0.81)、酸性洗涤不溶蛋白(R^2=0.88)、不可利用蛋白(R^2=0.85)及粗蛋白质快速降解部分(R^2=0.69)拟合最好。综上所述,不同种植地对全株青贮玉米蛋白质成分、CNCPS组分、干物质和粗蛋白质瘤胃降解参数及蛋白质分子结构均有影响。并且,蛋白质分子结构与蛋白质营养价值之间存在明显的相关关系,可以借助青贮玉米蛋白质红外光谱参数对其蛋白质营养价值进行预测。

The aim of this experiment was to explore the effects of different producing areas on the molecular structure of whole silage corn protein and its correlation with protein nutritional value and rumen degradation characteristics.This experiment used conventional chemical analysis methods combined with Cornell net carbo⁃hydrate⁃net protein system(CNCPS)and nylon bag technology to evaluate the nutritional value of whole silage corn in different producing areas.Fourier transform infrared spectroscopy(FTIR)technology was used to ana⁃lyze the changes of molecular structure of silage corn protein,and then to explore the correlation between them.The results showed as follows:1)there were significant differences in the chemical constituents of whole silage corn in different producing areas(P<0.05);there were significant differences in non⁃protein nitrogen,medi⁃um⁃speed degradation proteins,slow⁃degrading proteins and unavailable proteins of the CNCPS protein fraction(P<0.05);there were also significant differences in the effective degradation rates of dry matter and crude protein(P<0.05).2)After scanning by FTIR technology,it was found that amide bandⅠpeak height and peak area,amide Ⅱ band peak height and peak area,total peak area,peak area ratio,peak height ratio of am⁃ideⅠandⅡbands,α⁃helix,β⁃fold peak height in the molecular structure of whole silage corn in different producing areas had significant effects(P<0.05).3)Amide Ⅰ band peak height,peak area,amide Ⅱ peak height,peak area,amideⅠband andⅡband peak height ratio,peak area ratio andα⁃helix peak height could be used as predictors to predict the nutritional value and rumen degradation parameters of whole silage corn.A⁃mong them,silage corn protein molecular structure for crude protein(CP)(R^2=0.81),acid detergent insolu⁃ble protein(ADICP)(R^2=0.88),non⁃available protein(PC)(R^2=0.85)and crude protein rapid degrada⁃tion(CPa)(R^2=0.69)fitted the best.In summary,different producing areas have an effect on the protein components,CNCPS components,dry matter and crude protein rumen degradation parameters and protein mo⁃lecular structure of whole silage corn.Moreover,there is a clear correlation between protein molecular structure and protein nutritional value,and the protein nutritional value of silage corn can be predicted by infrared spec⁃tral parameters.