This experiment was performed to assess the effects of infusion of graded starch in abomasum on feed intake,lactation performance,gastrointestinal fermentation and blood metabolism of lactating cows. Four Holstein cows fitted with permanent ruminal cannulas were arranged into four groups by a 4×4 Latin square de-sign. Cows were infused with 0,800,1 600 and 2 400 g / d starch in abomasum,respectively. The experiment lasted for 7 days,which was consisted of a 5-day pre-experimental period and a 2-day experimental period. The results showed as follows:1)dry matter intake of dairy cows was not affected by abomasal starch infusion at different levels(P>0.05);with the increase of abomasal starch infusion level,digestive energy intake( P =0.022)and net energy for lactation intake(P = 0.014)were linearly increased,while starch apparent digesti-bility was linearly decreased(P = 0.029). 2)With the increase of abomasal starch infusion level,milk fat per-centage(P = 0.024)and yield(P = 0.022)were quadratically increased,those in 1 600 g / d group reached the highest. 3)Butyric acid concentration in fecal fluid in 800 g / d group was significantly lower than that in 1 600 and 2 400 g / d groups(P<0.05),and total volatile fatty acid concentration was significantly lower than that in control group and 1 600 g / d group( P<0.05). 4)Ruminal fermentation and blood metabolism indices were not affected by abomasal starch infusion at different levels( P>0.05). In conclusion,milk fat percentage is quadratically increased with the increase of abomasal starch infusion level,and the peak amount of rumen es-caped starch that can be utilized by dairy cows at late lactation period is 1 600 g / d.%为了研究真胃灌注不同水平淀粉对泌乳后期奶牛采食量、泌乳性能、胃肠道发酵和血液代谢的影响，采用4×4拉丁方设计将4头安装有永久性瘤胃瘘管的荷斯坦2胎奶牛分为4组，分别向真胃内灌注0（对照组）、800、1600、2400 g / d 淀粉。共进行4期试验，每期7 d（5 d的预试期和2 d 的正试期）。结果表明：1）真胃灌注不同水平淀粉对奶牛干物质采食量无显著影响（P＞0．05）；奶牛的消化能（ P ＝0．022）和泌乳净能采食量（ P ＝0．014）均随着真胃淀粉灌注量的增加而呈线性增加，而奶牛的淀粉表观消化率则呈线性降低（P ＝0．029）。2）随着真胃淀粉灌注量的增加，乳脂率（P ＝0．024）和乳脂产量（P ＝0．022）均呈二次曲线上升，以1600 g / d 灌注量时最大。3）800 g / d 组的粪液丁酸浓度显著低于1600和2400 g / d 组（P＜0．05），粪液总挥发性脂肪酸浓度显著低于对照组和1600 g / d 组（ P＜0．05）。4）真胃灌注不同水平淀粉对瘤胃发酵特性及血液代谢指标均无显著影响（P＞0．05）。综合以上，乳脂率随着真胃淀粉灌注量的增加呈二次曲线上升；泌乳后期奶牛能够利用的过瘤胃淀粉的最大量为1600 g / d。
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