The objective of this study was to evaluate the effect of particle size in pelleted diet on nutrient digestibility and growth performance of weaning piglets. 352 uncastrated males, aged 28 to 63 d, were distributed in a randomized block design (initial weight) according to treatments. The experimental feeds were divided into two phases, pre-initial (28 to 42 d) and initial (43 to 63 d) and produced with different corn particle sizes ground in a hammer mill, which provided a geometric mean diameter (GMD) of 394 µm, 534 µm, 647 µm, and 695 µm respectively, to the pre-initial phase diets. In the initial phase the GMD were 587 µm, 625 µm, 798 µm, and 943 µm. All feeds were pelleted (pellet diameter 2.5 mm) and supplied ad libitum. After an analysis of variance (P < 0.05), orthogonal contrasts were constructed to evaluate the linear and quadratic effect of increasing feed particle size on digestibility and growth performance. In the pre-initial phase, there was no difference in daily feed intake and daily weight gain between treatments; however, there was a quadratic response (P < 0.05) in feed/gain ratio, and the reduction of GMD to 534 µm was positively correlated with feed/gain ratio. In the initial phase, feed intake increased linearly (P < 0.05) with increasing GMD in the pelleted diet. GMD had no effect on feed/gain ratio, but there was a linear correlation (P < 0.05) between GMD and weight gain in this phase, owing to greater feed consumption. There was a linear response (P < 0.05) in dry matter and ether extract digestibility coefficients, with the highest values determined in pigs consuming the finest diets (587 µm). GMD had no effect on crude protein digestibility, but there was a quadratic correlation (P < 0.05) between particle size and digestible energy, as digestible energy reduced when GMD increased up to 798 µm, followed by a slight increase at 943 µm. In conclusion, as the weaning pigs become older, their growth performance response increases with increasing particle size of the pelleted diet. The GMD for an optimal pelleted feed is 534 µm for pre-initial and 943 µm for initial phase. Additionally, during the initial phase, fine particle sizes results in better efficiency of feed utilization.

这项研究的目的是评估颗粒饲料中粒径对断奶仔猪营养消化率和生长性能的影响。352名未割的雄性，年龄28至63 d，根据治疗方法分配为随机区组设计（初始重量）。实验饲料分为初始阶段（28到42 d）和初始阶段（43到63 d）两个阶段，并在锤磨机中以不同的玉米颗粒大小生产，其几何平均直径（GMD）为394到初始阶段饮食前分别为µm，534 µm，647 µm和695 µm。在初始阶段，GMD为587 µm，625 µm，798 µm和943 µm。将所有饲料造粒（小丸直径2.5mm）并随意提供。经过方差分析（P<0.05），构建正交对比来评估增加饲料粒度对消化率和生长性能的线性和二次效应。在初始阶段，两次治疗之间的日采食量和日增重没有差异。但是，进料/进料比有二次响应（P <0.05），而GMD降至534 µm与进料/进料比呈正相关。在初始阶段，随着颗粒饲料中GMD的增加，采食量线性增加（P <0.05）。GMD对饲料/增重比没有影响，但是由于饲料消耗量增加，该阶段GMD与体重增加之间存在线性关系（P <0.05）。有线性响应（P干物质和乙醚提取物的消化率系数<0.05），在食用最优质日粮（587 µm）的猪中确定的最高值。GMD对粗蛋白的消化率没有影响，但是颗粒大小与可消化能之间存在二次相关性（P <0.05），因为当GMD增加到798 µm时可消化能降低，随后在943 µm处略有增加。总之，随着断奶仔猪年龄的增长，它们的生长性能响应随着颗粒饲料日粮粒径的增加而增加。最佳颗粒饲料的GMD在初始阶段为534 µm，在初始阶段为943 µm。另外，在初始阶段，细粒度可提高饲料利用率。