体外产气法评价不同质量分级评分等级的全株玉米青贮的饲用价值

Evaluation of Feeding Value of Whole-Plant Corn Silage with Different Quality Score Grades by in Vitro Gas Production Method

本试验旨在通过体外产气法对不同质量分级评分(CSQS)等级的全株玉米青贮进行饲用价值评价,探究不同CSQS等级的全株玉米青贮瘤胃体外发酵30 h产气参数、营养物质降解率和发酵参数。在全国粮改饲全株玉米青贮饲料样品库中抽取5个CSQS等级的青贮饲料样品,每个等级随机抽取5个样品,共25个样品,进行体外产气评价。结果表明:1)5个等级全株玉米青贮之间30 h累积产气量具有差异显著趋势(P=0.06),且CSQS一级全株玉米青贮产气量最高。2)各等级全株玉米青贮间的干物质降解率(IVDMD)及氨态氮(NH3-N)、乙酸、丙酸含量差异显著(P<0.05),各等级全株玉米青贮间中性洗涤纤维降解率(IVNDFD)有差异显著趋势(P=0.07);CSQS一级全株玉米青贮IVDMD、IVNDFD、酸性洗涤纤维降解率(IVADFD)最高,乙酸和丙酸含量最高,NH3-N含量最低。CSQS一至五级,IVDMD、IVNDFD、IVADFD呈线性降低(P<0.05),乙酸和丙酸含量呈线性减少(P<0.05),NH3-N含量呈线性增加趋势(P=0.06)。各等级之间乙酸/丙酸差异不显著(P>0.05)。综上所述,全株玉米青贮CSQS等级越高,其质量越差,饲用价值越低。

The objective of this study was to evaluate feeding value of different grades of whole-plant corn silage by in vitro gas production method,and to learn the gas production parameters,nutrient degradation rate and fermentation parameters for 30 h.Samples were randomly selected from each of the five grades in the sample bank of the National Grain-to-Feed Whole-Crop Corn Silage Quality Grading Score Index(CSQS)study,for a total of 25 samples.The results showed as follows:1)there was a significant difference in gas production among the 5 grades of whole-plant corn silage(P=0.06),and the highest gas production was found in grade 1 of whole-plant corn silage.2)The in vitro dry matter degradation rate(IVDMD),ammonia nitrogen(NH3-N),acetic acid and propionic acid contents were significantly different among grades of whole-plant silage(P<0.05).There was a trend of significant difference(P=0.07)in the in vitro neutral detergent fiber degradation rate(IVNDFD)among the 5 grades of whole-plant corn silage,respectively.The highest values of IVDMD,IVNDFD,in vitro acid detergent fiber degradation rate(IVADFD),the highest contents of acetic acid and propionic acid and the lowest NH3-N content were all found in CSQS grade 1 whole-plant corn silage.From the CSQS grades 1 to 5,the values of IVDMD,IVNDFD and IVADFD,the contents of acetic acid and propionic acid decreased linearly(P<0.05),and the content of NH3-N increased linearly(P=0.06).There was no difference in acetate/propionate among different grades(P>0.05).In summary,the higher the grade of CSQS,the worse the quality and feeding value of whole-plant corn silage.