本试验旨在研究环模模孔参数对颗粒饲料加工质量及肉鸡生长性能的影响。通过固定模孔直径（3 mm）改变模孔长径比（6：1、8：1、10：1）以及固定模孔长径比（10：1）改变模孔直径（3.0、3.5、4.0 mm），生产5种不同直径及硬度的肉鸡颗粒饲料。选取864只体重相近的21日龄爱拔益加（AA）肉鸡，随机分成6组，每个组8个重复，每个重复18只。Ⅰ~Ⅴ组分别饲喂模孔直径和长径比分别为3.0 mm和6：1、3.0 mm和8：1、3.0 mm和10：1、3.5 mm和10：1、4.0 mm和10：1的颗粒饲料；Ⅵ组分2阶段饲喂，22~35日龄饲喂模孔直径和长径比为3.0 mm和10：1颗粒饲料，36~42日龄饲喂模孔直径和长径比为4.0 mm和10：1颗粒饲料。试验期21 d。结果表明：1）模孔直径相同时，颗粒硬度随着模孔长径比的增加而极显著提高（P<0.01）；模孔长径比相同时，颗粒硬度随着模孔直径的增加而极显著提高（P<0.01）。各组颗粒耐久性指数（PDI）无显著差异（P>0.05），且都高于95%。2）模孔直径相同时，随着颗粒硬度的增加，肉鸡终末体重、平均日增重均逐渐降低，料重比逐渐升高。Ⅰ组的终末体重和平均日增重显著或极显著高于Ⅲ组（P<0.05或P<0.01），Ⅰ组料重比显著低于Ⅱ、Ⅲ组（P<0.05）。3）模孔长径比相同时，各组终末体重、平均日增重和平均日采食量均无显著差异（P>0.05）；随着颗粒直径的增加料重比逐渐降低，且Ⅲ组料重比显著高于Ⅴ组（P<0.05）。综上所述，模孔长径比和直径的增大均会显著提高颗粒硬度。在一定范围内，提高颗粒硬度会使肉鸡终末体重和平均日增重降低，料重比升高，而增大颗粒直径则会使料重比降低。

This experiment was conducted to study the effects of ring die parameters on pellet quality and growth performance of broilers. By fixing the diameter of die hole (3.0 mm) and changing the length-radial ratio of die hole (6:1, 8:1 and 10:1), fixing length-radial ratio of die hole (10:1) and changing diameter of die hole (3.0, 3.5 and 4.0 mm) to produce 5 kinds of pellets feed with different diameter and hardness. A total of 864 broilers with similar body weight were randomly allocated into 6 groups with 8 replicates per group and 18 broilers per replicate. Broilers in the groups Ⅰ to Ⅴ were fed the pellet feed which the diameter and length-radial ratio of die hole were 3.0 mm and 6:1, 3.0 mm and 8:1, 3.0 mm and 10:1, 3.5 mm and 10:1, 4.0 mm and 10:1, respectively; broilers in the group Ⅵ were fed the pellet feed which the diameter and length-radial ratio of die hole were 3.0 mm and 10:1 at 22 to 35 days of age, and 4.0 mm and 10:1 at 36 to 42 days of age. The experiment lasted for 21 days. The results showed as follows:1) in the same diameter of die hole, the pellet hardness was significantly increased with the length-radial ratio of die hole increased (P<0.01). In the same length-diameter ratio of die hole, the pellet hardness was significantly increased with the diameter of die hole increased (P<0.01). There was no significant difference on pellet durability index (PDI) among all groups (P>0.05), and all PDI was higher than 95%. 2) In the same diameter of die hole, with the pellet hardness increased, the final body weight and average daily gain were decreased, while the ratio of feed to gain were increased. The final body weight and average daily gain of group Ⅰ were significantly higher than those of group Ⅲ (P<0.05 or P<0.01), the ratio of feed to gain of group Ⅰ was significantly lower than that of groups Ⅱ and Ⅲ (P<0.05). 3) In the same length-diameter ratio of die hole, there were no significant differences on the final body weight, average daily gain and average daily feed intake among all groups (P>0.05). The ratio of feed to gain was decreased with the diameter of die hole increased, and the ratio of feed to gain of group Ⅲ was significantly higher than that of group Ⅴ (P<0.05). In conclusion, the length-radial ratio and diameter of die hole can significantly increase the pellet hardness. In a certain scope, increasing pellet hardness can reduce the final body weight and average daily gain, raise the ratio of feed to gain, while increasing the pellet diameter can decrease the ratio of feed to gain.