本试验旨在研究不同粒度的全混合日粮（TMR）对肉羊生长性能、采食行为及消化代谢的影响，初步为规模化育肥肉羊养殖场建立合理的TMR生产标准。本研究分为2个试验，每个试验选择4月龄左右健康断奶绵羊公羔24只，体重为（35.4±5.1）kg，随机分为4组，每组6只，单栏饲养。试验采用4×4拉丁方设计，饲喂4种不同粒度的TMR（对应的搅拌时间分别TMR1：羊草20 min、苜蓿16 min、花生秸12 min、玉米青贮5 min；TMR2：羊草30 min、苜蓿24 min、花生秸18 min、玉米青贮5 min；TMR3：羊草40 min、苜蓿32 min、花生秸24 min、玉米青贮5 min；TMR4：羊草50 min、苜蓿40 min、花生秸30 min、玉米青贮5 min）。每个试验分4期，每期15 d，共60 d。结果表明：1）随着搅拌时间的增加，宾州筛分层第1层干物质含量逐渐降低，第2、3、4层逐渐升高，TMR的粒度逐渐降低；物理有效纤维（peNDF）8.0和peNDF1.18含量极显著降低（P<0.01）。2）试验1中，不同粒度的TMR对肉羊日增重、料重比无显著影响（P>0.05）；TMR粒度对肉羊日总采食时间无显著影响（P>0.05）；TMR粒度对肉羊日总反刍时间有显著影响（P<0.05），对肉羊每千克中性洗涤纤维（NDF）的咀嚼时间和反刍时间有显著影响（P<0.05），随着TMR粒度的减小，反刍时间和咀嚼时间缩短。3）试验2中，不同粒度的TMR对肉羊的干物质、有机物、NDF、酸性洗涤纤维和粗蛋白质（CP）表观消化率无显著影响（P>0.05）；对CP摄入量及每千克体重的粪CP、尿CP含量均无显著影响（P>0.05）；随着TMR粒度减小，peNDF8.0的摄入量呈降低的趋势，但差异不显著（P>0.05）。综上，在本试验设定条件下，TMR4较适合育肥肉羊，对应的搅拌时间分别为羊草50 min，苜蓿40 min，花生秸30 min，玉米青贮5 min；对应的宾州筛分层中干物质含量分别为第1层6.00%，第2层30.23%，第3层44.62%，第4层19.15%，对应的peNDF含量分别为peNDF8.0 14.67%，peNDF1.18 32.79%。

This experiment was aimed to investigate the effects of total mixed ration (TMR) with different particle sizes on growth performance, feeding behavior and digestibility and metabolism of mutton sheep, and initially establish a reasonable TMR production standard for large-scale fattening mutton sheep farms. This study included two experiments, and in each experiment, twenty-four healthy weaned male sheep aged about 4 months were selected and weighed (35.4±5.1) kg. They were randomly divided into 4 groups, 6 sheep in each group, and kept in a single column. The experiment used a 4×4 Latin square design to feed four different TMR (mixing time were TMR1:leymus chinensis 20 min, alfalfa 16 min, peanut stalk 12 min, corn silage 5 min; TMR2:leymus chinensis 30 min, alfalfa 24 min, peanut stalk 18 min, corn silage 5 min; TMR3:leymus chinensis 40 min, alfalfa 32 min, peanut stalk 24 min, corn silage 5 min; TMR4:leymus chinensis 50 min, alfalfa 40 min, peanut stalk 30 min, corn silage 5 min, respectively). Each experiment was divided into 4 periods, 15 days in each period. The results showed as follows:1) with the increase of mixing time, Penn state forage and TMR particle separator (PSPS) dry matter contents at level 1 was decreased, levels 2, 3 and 4 were increased, and the particle size of TMR were reduced gradually; the contents of physical effective neutral detergent fiber (peNDF)8.0 and peNDF1.18 were significantly reduced (P<0.01). 2) In experiment 1, the TMR particle sizes had no significant effects on the daily gain and feed/gain of mutton sheep (P>0.05); the TMR particle sizes had no significant effect on the total feeding time of mutton sheep (P>0.05), but had a significant effect on the chewing time and ruminating time of mutton sheep (P<0.05). With the decrease of TMR particle size, the ruminating time and the chewing time were gradually shortening. 3) In experiment 2, TMR with different particle sizes had no significant effects on the apparent digestibility of day matter, organic matter, neutral detergent fiber, acid detergent fiber and crude protein of mutton sheep (P>0.05). TMR with different particle sizes had no significant effect on crude protein intake, manure crude protein content and urine crude protein content (P>0.05). As the TMR particle size decreased, the intake of peNDF8.0 tended to decrease. In conclusion, under the conditions of this experiment, TMR4 is more suitable for fattening mutton sheep. The corresponding mixing time are:leymus chinensis 50 min, alfalfa 40 min, peanut stalk 30 min, and corn silage 5 min. The corresponding dry matter content of the PSPS are:6.00% of level 1, 30.23% of level 2, 44.62% of level 3, 19.15% of level 4, and the corresponding peNDF content are:peNDF8.0 14.67% and peNDF1.18 32.79%.