本文旨在研究饲粮中添加不同水平的丝兰提取物（YSE）对肉仔鸡小肠黏膜形态、食糜消化酶活力和营养物质表观代谢率的影响，为确定YSE的适宜添加量提供理论依据。试验选取128只1日龄爱拔益加（AA）肉仔鸡，基础饲粮预饲14 d后随机分为4个组，每组4个重复，每个重复8只鸡，YSE添加水平分别为0（对照组）、100、200和300 mg/kg，试验期28 d。28和42日龄时每个重复随机选取2只肉仔鸡屠宰，取十二指肠、空肠和回肠的前段观察小肠黏膜形态，取食糜测定消化酶活力，35日龄时每个重复选取1只鸡进行代谢试验。结果表明：与对照组相比，1）饲粮中添加100 mg/kg YSE显著提高了肉仔鸡28日龄时空肠绒毛高度（VH）及42日龄时十二指肠VH和绒毛高度/隐窝深度（V/C）（P<0.05）。2）饲粮中添加200 mg/kg YSE显著提高了肉仔鸡42日龄时回肠食糜胰蛋白酶（TRY）、脂肪酶（LPS）活力和十二指肠食糜LPS活力（P<0.05）。3）饲粮中添加200 mg/kg YSE显著提高了肉仔鸡干物质（DM）和粗蛋白质（CP）表观代谢率（P<0.05），而添加300 mg/kg YSE显著降低了CP表观代谢率（P<0.05）；100和200 mg/kg YSE组钙（Ca）、磷（P）表观代谢率呈升高趋势而300 mg/kg YSE组呈降低趋势（0.05 ≤ P < 0.10）。由此可见，从消化代谢功能看，YSE在肉仔鸡饲粮中的添加剂量以100~200 mg/kg为宜。

Effects of dietary different level of Yucca schidigera extract (YSE) on small intestinal mucosal morphology, activities of chymous digestive enzymes and apparent metabolic rates of nutrients of broilers were studied to provide a theoretical basis for determining YSE appropriate dosage in broiler diets. One hundred and twenty-eight one-day-old Arbor Acres (AA) broilers were randomly assigned to 4 groups with 4 replicates per group and 8 chicks per replicate after 14 days pre-feeding period with basal diets. The supplemental levels of YSE in diets were 0 (control group), 100, 200, and 300 mg/kg, respectively. The experimental period lasted for 28 days. At 28 and 42 days of age, two birds in each replicate were selected randomly and slaughtered, and the front parts of duodenum, jejunum and ileum were removed in order to observe small intestinal mucosal morphology, and small intestinal chyme was collected for analyzing the activities of digestive enzymes. At 35 days of age, one bird in each replicate was selected for metabolic experiment. The results showed as follows:compared with the control group, 1) diet added 100 mg/kg YSE significantly increased jejunum villus height (VH) of broilers at 28 days of age and duodenum VH and villus height/crypt depth (V/C) at 42 days of age (P<0.05). 2) Diet added 200 mg/kg YSE significantly increased the activities of trypsin (TRY) and lipase (LPS) in ileum chyme and LPS in duodenum chyme of broilers at 42 days of age (P<0.05). 3) Diet added 200 mg/kg YSE significantly increased the apparent metabolic rates of dry matter (DM) and crude protein (CP) of broilers (P<0.05), but diet added 300 mg/kg YSE significantly decreased CP apparent metabolic rate (P<0.05). What's more, the apparent metabolic rates of calcium (Ca) and phosphorus (P) in 100 and 200 mg/kg YSE groups showed an increasing trend but those in 300 mg/kg YSE group showed a decreasing trend (0.05 ≤ P < 0.10). In conclusion, the appropriate dosage of YSE in broiler diets is 100 to 200 mg/kg based on the digestive and metabolic functions.