中文摘要：

【目的】为探析补饲条件下，限时放牧对乌珠穆沁羔羊生长发育及采食量的影响。【方法】选择30只乌珠穆沁去势公羔，按照同质原则随机分成5组：0H为舍饲组（对照），2H、4H、8H、12H分别为放牧2、4、8、12 h组。各处理组饲粮代谢能水平接近。试验期102 d，预试期15 d，正式期87 d。7、8、9月份每月月末空腹称重、同时测量体尺，分别在每月中旬用饱和链烷法测定一次放牧采食量。【结果】（1）限时放牧加补饲对放牧季乌珠穆沁羔羊的体长、体高、胸围均无显著影响（P＞0.05）；但8月份，8H、12H组的体长指数均显著高于（P=0.05）舍饲组，其体躯指数显著低于（P＜0.05）舍饲组，而2H和4H组与舍饲组无显著差异（P＞0.05）。（2）各处理组7—9月份的月末体重、总增重、全期平均日增重、总采食量均没有显著差异（P＞0.05），但日增重在各月份之间显著不同（P＜0.01）。7月份，随放牧时间延长日增重显著降低（P＜0.01），全天放牧组的日增重较舍饲组、2H、4H、8H组分别减少了101、84、69、38 g？d-1，而放牧2H、4 H组与舍饲组无显著差别（P＞0.05）；8月份，各处理组日增重均达到最大，4H、8H、12H组显著高于（P=0.045）舍饲和2H组；9月份，舍饲组日增重显著高于（P＜0.05）其余4组，而其余各组之间无差异（P＞0.05）。（3）随放牧时间延长，放牧采食量显著增加（P＜0.001）而补饲量呈递减趋势；补饲量每增加1 kg，总采食量增加0.44 kg、放牧采食量减少0.78 kg；4H组的饲料转化效率略优于2H和8H组。【结论】限时放牧4 h加补饲不影响羔羊的总采食量和平均日增重，但显著减少了放牧采食量。结合草地保护和饲养成本，则放牧4 h加0.52 kg补饲（精料与谷草干草以1﹕1混合）是最佳放牧管理方式。

英文摘要：

【Objective】This study was conducted to investigate the effects of restricted access time to pasture combined with indoor feeding on growth performance and feed intake of Ujumuqin lambs. 【Method】Thirty castrated male Ujumuqin lambs were randomly assigned into five equal groups with similar metabolic energy diet： （i） alone feeding indoor （0H; control）, （ii） 2-h access to pasture （2H）, （iii） 4-h access to pasture （4H）, （iv） 8-h access to pasture （8H）, and （v） full-time access to pasture （12H）. Lambs were raised for 102 days, coinciding with a 15-d feed adaptation period and 87-d experimental periods. Body weight, height and length, and heart girth of the lambs were measured before eating in the morning （about 06：00 am） from last of July to September, once a month. The pasture intake was estimated using the n-alkane method in the middle of each month from July to September. 【Result】The restrictions at pasture did not significantly （P＞0.05） affect the amounts of body length and height, and heart girth of the lambs, but had significant （P＜0.05） effects on the ratios of length/height and chest/length. The ratios of length/height in the 8H and 12H groups were higher （P=0.05） compared to the 0H group. The ratios of chest/length in 0H, 2H and 4H groups were higher （P＜0.05） than the 12H group, respectively. No differences were found in final body weight, total weight gain, average daily weight gain （ADG）, and total feed intake of lambs among the five groups （P＞0.05）. In July, the weight gain significantly decreased （P＜0.01） as the grazing time increased. The gain of lambs of 12H group decreased by 101, 84, 69, and 38 g？d-1 （P＜0.01） as compared to the lambs of 0H, 2H, 4H, and 8H groups, respectively. The gain of grazing 2 and 4 h groups did not differ （P＞0.05） from the 0H group. In August, the maximum gain of lambs was observed in all groups. The lambs imposed with limited pasture access time of 4, 8, and 12 h had