体外产气法研究玉米碳水化合物不同组分的瘤胃发酵

在化学法剖分玉米碳水化合物组分的基础上,采用体外产气量法测定不同组分的动态产气量和发酵参数,为生产中利用康奈尔净碳水化合物和净蛋白质体系(CNCPS)预测饲料碳水化合物组分的瘤胃降解参数提供可用的方法。选取6个品种玉米籽粒,剖分出80%乙醇不溶组分(EIR)、中性洗涤纤维(NDF)及淀粉组分,随后测定全样、EIR、淀粉及NDF4种组分的体外产气量,并计算可溶性糖(组分A)的产气量和不同组分的理论最大产气量(B)、产气速率(C)、发酵延滞期(Lagtime)等参数。结果表明:全样、淀粉组分及NDF组分的48h产气量均存在高度正相关,组分A与其他3种组分的产气量在最初6h内存在高度正相关;产气速率从大到小依次为A组分>全样>淀粉组分>NDF组分;延滞期从大到小依次为淀粉>全样>NDF>A组分。

Fractionation and in vitro Gas Production of Different Carbohydrate Fractions of Corn Grains

In the Cornell Net Carbohydrate and Protein System Model (CNCPS), carbohydrate is divided into four fractions: A (sugars and organic acids), B1(starch and soluble fiber), B2 (digestible fiber), and C (indigestible residue). In the case of experiment, the carbohydrate of corn grains would be fractionated into different pool size, including the ethanol-insoluble residue (EIR), starch and neutral detergent fiber (NDF), and then the digestion kinetics for individual fractions were determined by an in vitro gas production method using 100 -mL glass syringes. The gas production of fraction A was obtained by subtracting the gas volume of EIR from the total gas production of intact corn grains at each time point. The gas production of starch stands for the gas production of B1 and the NDF for the B2. For each corn sample, gas production data of different fractions were fitted to an exponential equation (Y = B (1 - e -c (t - lag))) with discrete lag using SAS. The objectives of this study were to fractionate carbohydrates of corn grains and compare the difference of fermentation characteristics in vitro between different carbohydrate fractions of corn grains.