中文摘要：

在北农大高油（BHO）米群体的16个选择轮次中隔轮选取籽粒样品为试验材料，利用活体外人工瘤胃产气量方法。研究HOC籽粒含油量的选择进程对BHO群体籽粒的化学组成、活体外干物质和淀粉消化率以及瘤胃发酵参数的影响。BHO群体的籽粒含油量从第2轮的6．84％提高至第16轮的13．20％，分别与籽粒淀粉和蛋白质含量呈现显著的负相关（r=-0．84，P〈0．001）和正相关（r=0．74，P〈0．001）。随着含油量选择进程的提高。HOC籽粒的活体外产气速度和淀粉消化率线性增加（P〈0．001），这可能源于BHO群体的淀粉结构随含油量选择进程发生了改变。理论最大产气量和活体外干物质消化率随含油量选择轮次的提高而线性降低（P〈0．001）。活体外发酵6h的pH、总挥发酸（mmol／L）和丙酸比例（％）线性提高（P〈0．001），乙酸和丁酸的比例线性下降（P〈0．001）。活体外发酵24h以后，不同选择轮次间的各项发酵参数均无显著差异。

英文摘要：

An in vitro gas production experiment was conducted to investigate the effect of oil selection progress of Beinongda high oil （BHO） population on chemical composition, ruminal digestion characteristics and fermentation traits in vitro. The experimental HOC grains were alternately obtained from 16 oil-selecting cycles of BHO population. With genetic selection progress, the fat content of BHO population linearly increased from 6.84% in cycle 2 to 13.20% in cycle 16. The starch and protein content in HOC grain quadratically responded to the selection progress, and there were close correlations between the content of starch and fat （r = - 0.83, P 〈 0.001 ） in one hand and between the content of protein and fat （r = 0.75, P〈0.001） in the other hand. Rate and extent of starch digestion significantly increased in a linear fashion with increased selecting cycles, indicating that genetic selection for oil in such BHO population probably altered the structure of endosperm layers or texture of starch granules. Accumulative gas amount during 48 h fermentation and DM digestibility at 24 h incubation time significantly declined with increased selecting cycles. This may be attributable to the reduced starch content with the increased fat content, rather than to any direct effect of increased fat. As fat content increased, the pH value, total VFA concentration and propionate molar percentage also significantly increased in a linear fashion and molar Droportions of acetate and butyrate linearly declined at 6h incubation time. However, these values did not differ at 24 h incubation time.