本文旨在研究玉米粒度对蛋鸡消化道生理和饲料流通速率的影响，为更大程度地发挥饲料加工对动物生产的积极作用提供参考方案。选用774只38周龄的罗曼粉壳蛋鸡，按产蛋率分为3个处理，每个处理6个重复，每个重复43只鸡，分别饲喂由粗（1 001.70 μm）、中（824.97 μm）和细（671.56 μm）3种粒度玉米配制成的饲粮，16周后每个重复屠宰1只鸡用以取组织样品，再从每个重复另选取1只鸡进行24 h饲料流通速率试验。结果表明，最小粒度组的溃疡评分显著高于粗颗粒组和中等颗粒组（P<0.05）；玉米粒度对十二指肠隐窝深度、绒毛高度和绒毛高/隐窝深无显著影响(P>0.05)，但粗颗粒组的十二指肠壁厚显著高于细颗粒组（P<0.05）；各粒度组间盲肠内容物中乳酸杆菌和双歧杆菌数差异均不显著（P>0.05），但大肠杆菌菌群数以细粒度组最高，中等粒度组最低，且这2组间差异显著（P<0.05）；饲粮玉米粒度的减小能显著增加第2、4、6小时蛋鸡粪中的Cr2O3相对回收率(P<0.05)，及显著降低第10、12、16小时蛋鸡粪中的Cr2O3相对回收率(P<0.05)。饲粮玉米粒度的减小能显著增加前2个小时（P<0.05）及极显著增加前4和前6个小时（P<0.01）蛋鸡粪中的Cr2O3累积回收率，但对前8、10、12、16和24个小时的Cr2O3累积回收率无显著影响(P>0.05)。本研究表明，玉米粒度的增大有助于改善蛋鸡胃肠道的生理状况和延长食糜在消化道停留的时间。

The experiment was conducted to study the effects of corn grains particle size on the gastrointestinal physiology and feed passage rate of laying hens fed corn-soybean diet. A total of 774 pink-shell Lohmann commercial laying hens of 38 weeks old were randomly allocated by laying rate to 3 treatments with 6 replicates per treatment and 43 hens per replicate. The 3 treatments differed only in corn grains particle size (coarse: 1 001.70 μm, medium: 824.97 μm and fine: 671.56 μm). The experiment lasted for 16 weeks. In the end, one hen from each replicate was killed and gastrointestinal samples were taken; another one from each replicate was chosen for a 24 hours’ trial to determine the effect of corn grains particle size on feed passage rate in hens. The results showed that: 1) hens fed coarse corn had a significant lower ulcer score of gizzard than those fed fine corn (P<0.05); 2) corn grains particle size had no effect on crypt depth, villus height and villus/crypt ratio of duodenum (P>0.05), but hens fed coarse corn had significant higher wall thickness (P<0.05) than those fed fine corn; 3) corn grains particle size had no effect on Lactobacillus and Bacillus bifidus concentration while the fine corn group had a significant lower E. coli concentration compared with the coarse corn group (P<0.05); 4) as corn grains particle size decreased, the relative recovery rates of fecal Cr2O3 at 2, 4 and 6 h were significantly increased (P<0.05), but were significantly decreased at 10, 12 and 16 h (P<0.05). Cumulative recovery rate of fecal Cr2O3 was significantly increased at 2 h (P<0.05) and very significantly increased at 4 and 6 h (P<0.01) as corn grains particle size decreased, but no significant differences were found at 8, 10, 12, 16 and 24 h (P>0.05). In the condition of this study, it is concluded that the increasing of dietary corn grains particle size can improve gastrointestinal physiology and nutrient retention in gastrointestinal tract of laying hens.［Chinese Journal of Animal Nutrition, 2010，22（5）:1271-1278］