本试验旨在研究二次制粒工艺下膨化玉米添加比例对颗粒饲料加工质量以及断奶仔猪生长性能、养分表观消化率与血清生化指标的影响。饲粮设5种膨化玉米添加比例（膨化玉米添加量占玉米添加总量的百分比），分别为0、25%、50%、75%、100%，采用二次制粒工艺进行颗粒饲料的加工。选用28日龄初始体重为（8.57±0.87）kg的断奶仔猪80头，随机分为5组，每组4个重复，每个重复4头猪，进行50 d的饲养试验，分为前期（第1~28天）、后期（第29~50天）2个阶段。结果表明：1）在颗粒饲料加工质量方面，颗粒饲料硬度、颗粒饲料耐久性指数（PDI）、淀粉糊化度随着膨化玉米添加比例的增加而增加。2）在断奶仔猪生长性能方面，前期末重、平均日增重、平均日采食量各组之间无显著差异（P>0.05），料重比则表现为未添加组显著高于其他组（P<0.05）；后期末重、平均日增重、平均日采食量、料重比各组之间无显著差异（P>0.05）；全期末重、平均日增重、平均日采食量、料重比各组之间无显著差异（P>0.05）。3）在断奶仔猪养分表观消化率方面，干物质与粗蛋白质表观消化率均以100%组最高，未添加组最低，且未添加组均显著低于各添加膨化玉米组（P<0.05）。4）在断奶仔猪血清生化指标方面，75%组血清总蛋白含量显著高于未添加组、50%组和100%组（P<0.05）；未添加组血清甘油三酯含量显著高于50%组、75%组和100%组（P<0.05）；100%组血清碱性磷酸酶活性显著高于未添加组（P<0.05）；50%组血清钙含量显著低于其他各组（P<0.05）。综合考虑膨化玉米添加比例对颗粒饲料硬度、断奶仔猪生长性能和加工成本的影响，建议在二次制粒工艺条件下，断奶仔猪饲粮中膨化玉米添加量为玉米添加总量的25%。

This experiment was conducted to evaluate the effects of expanded corn additive proportion under the secondary pelleting process on the processing quality of pellet feed and growth performance, nutrient apparent digestibility and serum biochemical indexes of weaned piglets. Five expanded corn additive proportions (the percentage of additive amount of expanded corn to total additive amount of corn) were designed in diets which were 0, 25%, 50%, 75% and 100%, respectively, and the diets were made into pellet feed by secondary pelleting process. Eighty 28-day-old weaned piglets with an initial body weight of (8.57±0.87) kg were randomly divided into 5 groups with 4 replicates per group and 4 weaned piglets per replicate. The experiment lasted for 50 days, and it was divided into 2 stages:early stage (the 1st to 28th day) and later stage (the 29th to 50th day). The results showed as follows:1) in the pellet feed processing quality, the pellet feed hardness, pellet durability index (PDI) and starch gelatinization degree were increased with the additive proportion of extruded corn increasing. 2) In the growth performance of weaned piglets, in early period, there were no significant differences among groups in the final body weight, average body weight (ADG) and average daily feed intake (ADFI) (P>0.05), but the feed conversion rate (FCR) in no-added group was significantly higher than that in other groups (P<0.05); in later period, there were no significant differences among groups in the final weight, ADG, ADFI and FCR (P>0.05); in full period, there were no significant differences among groups in the final weight, ADG, ADFI and FCR (P>0.05). 3) In the nutrient apparent digestibility of weaned piglets, the dry matter apparent digestibility and crude protein apparent digestibility in 100% group had the highest values and in no-added group had the lowest values, and they in no-added group were significantly lower than those in added expanded corn groups (P<0.05). 4) In the serum biochemical indexes of weaned piglets, the serum total protein content in 75% group was significantly higher than that in no-added group, 50% group and 100% group (P<0.05); the serum triglyceride content in no-added group was significantly higher than that in 50% group, 75% group and 100% group (P<0.05); the serum alkaline phosphatase (ALP) activity in 100% group was significantly higher than that in no-added group (P<0.05); the serum calcium content in 50% group was significantly lower than that in other groups (P<0.05). Considering the effects of the additive proportion of expanded corn on the pellet feed hardness, the growth performance of weaned piglets and the processing cost, it is suggested that the additive amount of expanded corn in the diet of weaned piglets is 25% of the total additive amount of corn under the secondary pelleting process.