奶牛常用饲料康奈尔净碳水化合物-蛋白质体系中含氮化合物组分含量与可利用氨基酸含量之间的关系

Relationships between Contents of Nitrogenous Fractions of Cornell Net Carbohydrate and Protein System and Utilizable Amino Acids of Major Feeds for Dairy Cows

为了预测奶牛常用饲料中可利用氨基酸(u AA)的含量,本试验采集了21个奶牛饲料原料样品,测定了饲料样品的粗蛋白质(CP)、粗脂肪(EE)、粗灰分(ash)、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)、可溶性粗蛋白质(SCP)、非蛋白氮(NPN)、中性洗涤剂不溶粗蛋白质(NDIP)、酸性洗涤剂不溶粗蛋白质(ADIP)含量,并根据康奈尔净碳水化合物-蛋白质体系(CNCPS)对饲料含氮化合物组分的划分方法,计算出饲料样品的含氮化合物组分非蛋白氮(PA)、快速降解真蛋白质(PB1)、中速降解真蛋白质(PB2)、慢速降解真蛋白质(PB3)和不可利用蛋白质(PC)的含量,测定了饲料的氨基酸含量,同时利用饲料氨基酸含量与u AA含量之间的关系估测出饲料的u AA含量。结果表明,奶牛常用饲料的CNCPS含氮化合物组分(PA、PB1、PB2、PB3、PC)含量(%DM)与u AA、可利用蛋氨酸(utilizable methionine,u Met)、可利用赖氨酸(utilizable lysine,u Lys)、可利用亮氨酸(utilizable leucine,u Leu)含量(%DM)存在显著的相关关系,回归方程如下:u AA=0.171PA+0.134PB1+0.364PB2+0.370PB3+0.148PC+7.785,R2=0.99,P<0.01;u M et=0.019PA-0.031PB1+0.024PB2+0.078PB3-0.004PC-0.071,R2=0.93,P<0.01;u Lys=-0.045PA-0.020PB1+0.072PB2+0.038PB3-0.011PC+0.780,R2=0.92,P<0.01;u Leu=0.071PA+0.033PB1+0.093PB2+0.189PB3+0.003PC+0.006,R2=0.94,P<0.01。结果显示,根据CNCPS含氮化合物组分和本试验所建立的方程,可以准确地预测奶牛饲料的u AA、u M et、u Lys和u Leu含量。

To predict the utilizable amino acid（uAA） contents of major feeds for dairy cows,twenty-one different feed samples were collected and analyzed for the contents of crude protein（CP）,ether extract（EE）,neutral detergent fibre（NDF）,acid detergent fibre（ADF）,soluble crude protein（SCP）,non-protein nitrogen（NPN）,neutral detergent unsoluble crude protein（NDIP） and acid detergent unsoluble crude protein（ADIP）.The contents of nitrogenous fractions including non-protein nitrogen（PA）,rapidly degraded true protein（PB_1）,intermediately degraded true protein（PB_2）,slowly degraded true protein（PB_3） and unutilizable protein（PC） were calculated according to CNCPS.The contents of amino acids of feed samples were also analyzed.The contents of uAAs of feeds were calculated based on the relationships between feed amino acid and uAA.The results showed that the CNCPS nitrogenous fraction（PA,PB_1,PB_2,PB_3 and PC） contents（%DM） were highly correlated with uAA,utilizable methionine（uMet）,utilizable lysine（uLys） and utilizable leucine（uLeu） contents（%DM）,and the regression equations were as follows：uAA =0.171 PA ＋0.134PB_1＋0.364PB_2＋0.370PB_3＋0.148PC＋7.785,R^2=0.99,P〈0.01;uMet=0.019PA-0.031PB_1＋0.024PB_2＋0.078PB_3-0.004PC-0.071,R^2=0.93,P〈0.01;uLys=-0.045PA-0.020PB_1＋0.072PB_2＋0.038PB_3-0.011PC＋0.780,R^2 =0.92,P〈0.01;uLeu=0.071PA＋0.033PB_1＋0.093PB_2＋0.189PB_3＋0.003PC＋0.006,R^2 = 0.94,P〈0.01.It is concluded that uAA,uMet,uLys and uLeu of feeds for dairy cows can be predicted based on the CNCPS nitrogenous fraction contents and the equations established in the trial.