全株玉米青贮饲料在奶牛瘤胃中的干物质、淀粉及中性洗涤纤维降解特性研究与预测模型建立

Degradation Characteristics and Prediction Model of Dry Matter,Starch and Neutral Detergent Fiber of Whole-Pant Corn Silage in Cow Rumen

本研究采用体外法测定全株玉米青贮饲料在奶牛瘤胃中的降解特性,并分析了其营养成分与有效降解率(ED)的相关性,旨在寻求干物质(DM)、淀粉(Starch)、中性洗涤纤维(NDF)有效降解率的快速评定方法。以奶牛场不同贮存时期的玉米青贮饲料为研究对象,采用体外人工瘤胃持续发酵法,测定DM、Starch、NDF有效降解率,并分析与其营养成分的相关性,建立营养成分与DM、Starch、NDF有效降解率的数学模型。结果表明:1)在青贮60、150和240 d时,全株玉米青贮饲料DM、Starch和NDF有效降解率在60 d时最高,分别为33.40%、78.91%和25.53%。2)全株玉米青贮饲料DM有效降解率与粗蛋白质(CP)含量呈极显著正相关关系(P<0.01),与NDF、酸性洗涤纤维(ADF)含量呈极显著负相关关系(P<0.01);Starch有效降解率与Starch含量呈极显著正相关关系(P<0.01);NDF有效降解率与NDF、ADF含量呈极显著或显著负相关关系(P<0.01或P<0.05),与CP含量呈显著正相关关系(P<0.05)。3)全株玉米青贮DM有效降解率与非纤维性碳水化合(NFC)含量呈极显著正相关关系(P<0.01),与碳水化合物(CHO)、可消化纤维(CB3)、不消化纤维(CC)含量呈极显著负相关关系(P<0.01);Starch有效降解率与CHO、NFC含量呈显著正相关关系(P<0.05),与挥发性脂肪酸(CA1)、乳酸(CA2)、水溶性碳水化合物(CA4)、可溶性纤维(CB2)含量呈显著或极显著负相关关系(P<0.05或P<0.01);NDF有效降解率与CHO、CB3、CC含量呈极显著负相关关系(P<0.01),与NFC含量呈极显著正相关关系(P<0.01)。4)以CP、NDF、ADF、Starch含量为预测因子建立的DM、Starch有效降解率的预测模型分别为:ED(DM)=54.777-0.439NDF-0.004ADF(R2=0.973,n=51,P<0.0001);ED(Starch)=55.434+0.987Starch(R2=0.843,n=51,P<0.0001);ED(NDF)=75.786-0.765CP-1.036NDF+0.310ADF(R2=0.879,n=51,P<0.0001)。5)以CHO、NFC、CB3、CHO、NFC、CA2、CA4、CB2、CC含量为预测因子建立的DM、Starch有效降解率的预测模型分别为:ED(DM)=66.158-0.488CHO+0.330NFC-0.079CC(R2=0.980,n=51,P<0.0001);ED(Starch)=45.754-3.564CA4-0.827CB2+0.159CHO-0.692CA2+0.960NFC(R2=0.894,n=51,P<0.0001);ED(NDF)=41.972-0.457CHO+0.753NFC-0.697CC(R2=0.810,n=51,P<0.0001)。由此可知,基于全株玉米青贮饲料营养成分与DM、Starch、NDF有效降解率的强相关性,可快速、有效地评价饲料降解性能,为奶牛场饲料营养价值评定提供参考。

This study determined the rumen degradation characteristics of whole-plant corn silage by in vitro method,and analyzed the correlation between the nutrient composition and its effective degradability,and aimed to find a rapid assessment method for the effective degradability of dry matter(DM),starch and neutral detergent fiber(NDF).Taking corn silage in different storage periods of dairy farms as the research object.The in vitro artificial rumen continuous fermentation method was used to determine the effective degradability of DM,starch,and NDF and the correlation between the nutrient composition of whole-plant corn silage and its effective degradability was analyzed.The mathematical model of nutrient composition and effective degradability of DM,starch and NDF was established.The results showed as follows:1)at silage 60,150 and240 h,the ruminal degradability of DM,starch and NDF was the highest when stored for 60 d,which were33.40%,78.91%and 25.53%,respectively.2)The effective degradability of whole-plant corn silage DMwas extremely significant positive correlated with crude protein(CP)content(P<0.01),and extremely significant negative correlated with NDF and acid detergent fiber(ADF)content(P<0.01).The effective degradability of starch was extremely significant positive correlated with starch content(P<0.01).The effective degradability of NDF was significant negative correlated or extremely significant negative correlated with NDF and ADF content(P<0.05 or P<0.01),and significant positive correlated with CP content(P<0.05).3)The effective degradability of whole-plant corn silage DMwas extremely significant positive correlated with NFC content(P<0.01),and extremely significant negative correlated with carbohydrate(CHO),digestible fibre(CB3)and indigestible fibre(CC)contents(P<0.01).The effective degradability of starch was significant positive correlated with CHO and NFC contents(P<0.05),and significant negative correlated or extremely significant negative correlated with volatile fatty acids(CA1),lactic acid(CA2),water-soluble carbohydrates(CA4),soluble fiber(CB2)contents(P<0.05 or P<0.01).The effective degradability of NDF was extremely significant negative correlated with CHO,CB3 and CC contents(P<0.01),and extremely significant positive correlated with NFC content(P<0.01).4)Prediction equations for effective degradability of DMand starch using CP,NDF,ADF and starch were ED(DM)=54.777-0.439 NDF-0.004 ADF(R2=0.973,n=51,P<0.0001);ED(Starch)=55.434+0.987 Starch(R2=0.843,n=51,P<0.0001);ED(NDF)=75.786-0.765 CP-1.036 NDF+0.310 ADF(R2=0.879,n=51,P<0.0001).5)Prediction equations for effective degradability of DMand starch using CHO,NFC,CB3,CHO,NFC,CA2,CA4,CB2 and CC were ED(DM)=66.158-0.488 CHO+0.330 NFC-0.079 CC(R2=0.980,n=51,P<0.0001);ED(Starch)=45.754-3.564 CA4-0.827 CB2+0.159 CHO-0.692 CA2+0.960 NFC(R2=0.894,n=51,P<0.0001);ED(NDF)=41.972-0.457 CHO+0.753 NFC-0.697 CC(R2=0.810,n=51,P<0.0001).In summary,based on the strong correlation between the nutrient content of whole-plant corn silage and the effective degradability of DM,starch and NDF,the degradation performance of feed can be evaluated quickly and effectively,which provides a reference for the nutritional value assessment of feed in dairy farm.