本试验旨在研究不同粉碎粒度对饲料加工质量的影响以及肉鸡不同粉碎粒度饲粮对不同生长阶段肉鸡生长性能的影响。选用864只1日龄白羽爱拔益加（AA）肉鸡，随机分为6组，每组8个重复，每个重复18只鸡，进行为期42 d的饲养试验，分为前期（1~21日龄）和后期（22~42日龄）2个阶段。前、后期饲粮分别采用1.5、2.0和2.5 mm筛片孔径进行粉碎，每个筛片孔径设4个重复。前期设3个组，1.5 mm组设24个重复，2.0 mm组设16个重复，2.5 mm组设8个重复；后期设6个组，将前期1.5 mm组平均分为3个组，2.0 mm组平均分为2个组，2.5 mm组不变，每组8个重复。结果表明：1）饲料的几何平均粒径随着筛片孔径的增加而增加，其中2.5 mm组的几何平均粒径显著大于1.5和2.0 mm组（P<0.05）；颗粒耐久性指数（PDI）、颗粒硬度和淀粉糊化度随着筛片孔径的增加而降低，其中1.5 mm组的PDI和颗粒硬度显著大于2.0和2.5 mm组（P<0.05）；随着筛片孔径的增加，各组饲料的粗蛋白质体外消化率无显著差异（P>0.05）。2）1~21日龄时，2.0 mm组的21日龄平均体重、平均日采食量和平均日增重均为最高。22~42日龄时，前期2.0 mm、后期2.5 mm组的42日龄平均体重和平均日增重最高，料重比最低；前期1.5 mm、后期2.5 mm组的平均日采食量最高。综合以上结果，前期2.0 mm、后期2.5 mm组的生长性能最好。所以，肉鸡前期饲粮采用筛片孔径为2.0 mm、后期饲粮采用筛片孔径为2.5 mm进行粉碎，生长性能最佳。

This study was conducted to evaluate the effects of different particle sizes on feed processing quality and growth performance of broilers at different growth stages. Eight hundred and sixty four one-day-old white feather Arbor Acres (AA) broilers were randomly divided into 6 groups with 8 replicates per group and 18 boilers per replicate. The experiment lasted for 42 days consisting of early period (1 to 21 days of age) and later period (22 to 42 days of age) two periods. The diets of early period and later period were grinded by 1.5, 2.0 and 2.5 mm mesh size of screen, respectively, and 4 replicates were set per mesh size of screen. Three groups were set in early period, twenty four replicates were set in 1.5 mm group, sixteen replicates were set in 2.0 mm group, and eight replicates were set in 2.5 mm group. Six groups were set in later period, 1.5 mm group was divided into 3 equal groups, 2.0 mm group was divided into 2 equal groups, and 2.5 mm group was the same, eight replicates were set per group. The results showed as follows:1) geometric mean particle size of feeds was increased with the increase of mesh size of screen, and geometric mean particle size in 2.5 mm group was significantly higher than that in 1.5 and 2.0 groups (P<0.05). Particle durability index (PDI), particle hardness and starch gelatinization degree were decreased with the increase of mesh size of screen, and PDI and particle hardness in 1.5 mm group were significantly higher than those in 2.0 and 2.5 groups (P<0.05). There was no significant difference in crude protein digestibility in vitro of feeds among all group with the increase of mesh size of screen (P>0.05). 2) Average body weight at 21 days of age, average daily feed intake (ADFI) and average daily gain (ADG) in 2.0 mm group were the highest from 1 to 21 days of age. Average body weight at 42 days of age and ADG in 2.0 mm in early period and 2.5 mm in later period group were the highest and the ratio of feed to gain was the lowest, and ADFI in 1.5 mm in early period and 2.5 mm in later period group was the highest from 22 to 42 days of age. The results show that growth performance in 2.0 mm in early period and 2.5 mm in later period group is the best. Thus, the diets are grinded by 2.0 mm mesh size of screen in early period and 2.5 mm mesh size of screen in later period to get the best growth performance of broilers.