中文摘要：

选择4头安装有永久性瘤胃、十二指肠前端和回肠末端T形瘘管的荷斯坦泌乳奶牛，按4×4拉丁方设计，分别以铬染纤维和Co—EDTA为食糜固相和液相指示剂，研究精粗比约为30：70的“高低质粗料型”日粮、30：70的混合型高青贮日粮、50：50的精粗料比例相当的日粮及65：35的高精料日粮等4种日粮对瘤胃食糜稀释率及干物质（dry matter，DM）、有机物（organic matter，OM）、中性洗涤纤维（neutral detergent fiber，NDF）和酸性洗涤纤维（acid detergent fiber，ADF）等养分进食量、十二指肠流量及消化道不同部位表观消化率的影响。结果表明：日粮精粗比显著（P〈0．05）或极显著（P〈0．01）影响奶牛DM、OM、NDF和ADF进食量、十二指肠流量及DM、OM和ADF瘤胃表观降解率，而对奶牛瘤胃食糜液相和固相稀释率、NDF瘤胃表观降解率及DM、OM、NDF和ADF后肠道和全消化道表观消化率没有影响（P〉0．05）．

英文摘要：

Effects of dietary concentrate-to-forage ratio on the rate of dilution of ruminal digesta, and intake, duodenal flow, and apparent digestibility at different sites of digestive tract for nutrients, such as dry mater （DM）,organic matter （OM）,neutral detergent fiber （NDF） and acid detergent fiber （ADF）, were evaluated using four primiparous Holstein cows with permanently ruminal cannula, simple T-type duodenal and ideal cannulas in a 4× 4 Latin square design with four 20-d periods. The external tureen digesta markers were Co-EDTA for fluid phase and Cr-mordanted straw for solid phase. Dietary concentrate-to-forage ratios were 30 ： 70, 30 ： 70, 50 ： 50, and 65 ： 35, respectively. The forage of the ration 1 was only Chinese wildryegrass hay. The forage of the ration 2, 3, and 4 comprised of Chinese wildryegrass hay, alfalfa hay, and corn silage. The results showed that： the dietary concentrate-to-forage ratio significantly （P〈0.05） affected the intake and duodenal flow of nutrients and rumen apparent digestibility of DM, OM and ADF, but did not affect （P〉0.05） the rate of dilution for fluid phase and solid phase of ruminal digesta, rumen apparent digestibility of NDF and the apparent digestibility of post-rumen and total tract of nutrients.