本试验旨在通过内源指示剂法结合套算法比较甘蔗副产物的养分表观消化率。选取约1周岁、体重350 kg左右的西门塔尔公牛36头，随机分为6组，每组6个重复，每个重复1头。试验1：测定甘蔗尾叶青贮的养分表观消化率，分为试验Ⅰ期和试验Ⅱ期，试验Ⅰ期组1饲喂象草为粗饲料的全混合日粮（TMR），组2饲喂30%（干物质基础）的甘蔗尾叶青贮替换象草的TMR；试验Ⅱ期组1饲喂饲喂30%（干物质基础）的甘蔗尾叶青贮替换象草的TMR，组2饲喂象草为粗饲料的TMR；每期持续14 d，包括9 d的预试期和5 d的试验期，整个试验共计28 d。碱化蔗渣（试验2）和膨化蔗渣（试验3）试验设计同甘蔗尾叶青贮。结果表明：甘蔗尾叶青贮、碱化蔗渣和膨化蔗渣的干物质表观消化率分别为83.18%、59.74%和62.22%，有机物表观消化率分别为74.74%、58.96%和61.56%，总能表观消化率分别为70.98%、59.61%和62.72%，粗蛋白质表观消化率分别为66.93%、12.16%和15.69%，中性洗涤纤维表观消化率分别为47.47%、32.65%和38.28%，酸性洗涤纤维表观消化率分别为33.77%、25.70%和22.04%，可消化粗蛋白质含量分别为5.21%、0.21%和0.33%，消化能分别为12.78、10.14和10.76 MJ/kg。甘蔗尾叶青贮的干物质、有机物、粗蛋白质、中性洗涤纤维、酸性洗涤纤维和总能表观消化率显著高于碱化蔗渣和膨化蔗渣（P<0.05），膨化蔗渣的粗蛋白质和中性洗涤纤维表观消化率显著高于碱化蔗渣（P<0.05），膨化蔗渣的酸性洗涤纤维消化率表观显著低于碱化蔗渣（P<0.05）。综合上述结果，3种甘蔗副产物中以甘蔗尾叶青贮饲用价值最高，膨化蔗渣优于碱化蔗渣。

This experiment was conducted to compare the nutrient apparent digestibility of sugarcane by-products by endogenous indicator method combining with substitution method. Thirty-six 1-year-old Simmental bulls with body weight of about 350 kg were selected and divided into 6 groups with 6 replicates in each group and 1 cattle in each replicate. Test 1:the experimental design was for determining the nutrient apparent digestibility of sugarcane tops silage, which was divided into test Ⅰ phase and test Ⅱ phase, In the test Ⅰ phase, group 1 was fed a total mixed ration (TMR) which was used elephant grassy as roughage, and group 2 was fed a TMR which used 30% (dry matter basis) sugarcane tops silage instead of elephant grass; in the test Ⅱ phase, group 1 was fed a TMR which used 30% (dry matter basis) sugarcane tops silage instead of elephant grass, and group 2 was fed a TMR which was used elephant grassy as roughage. Each phase lasted for 14 days, including 9 days of pre-test period and 5 days of test period, and the total test period was 28 days. The alkalized sugarcane bagasse (test 2) and steam explosion sugarcane bagasse (test 3) were designed to be the same as the sugarcane tops silage. The results showed that the dry matter apparent digestibility of sugarcane tops silage, alkalized sugarcane bagasse and steam explosion sugarcane bagasse was 83.18%, 59.74% and 62.22%, respectively; the organic matter apparent digestibility was 74.74%, 58.96% and 61.56%, respectively; the gross energy apparent digestibility was 70.98%, 59.61% and 62.72%, respectively; the crude protein apparent digestibility was 66.93%, 12.16% and 15.69%, respectively; the neutral detergent fiber apparent digestibility was 47.47%, 32.65% and 38.28%, respectively; the acid detergent fiber apparent digestibility was 33.77%, 25.70% and 22.04%, respectively; the digestible crude protein content was 5.21%, 0.21% and 0.33%, respectively; and the digestible energy was 12.78, 10.14 and 10.76 MJ/kg, respectively. The apparent digestibility of dry matter, organic matter, crude protein, neutral detergent fiber, acid detergent fiber and gross energy of sugarcane tops silage was significantly higher than that of alkalized sugarcane bagasse and steam explosion sugarcane bagasse (P<0.05), the apparent digestibility of crude protein and neutral detergent fiber of steam explosion sugarcane bagasse was significantly higher than that of alkalized sugarcane bagasse (P<0.05), the apparent digestibility of acid detergent fiber of steam explosion sugarcane bagasse was significantly lower than that of alkalized sugarcane bagasse (P<0.05). Based on the above results, among the 3 kinds of sugarcane by-products, the sugarcane top silages have the highest feeding value, and the steam explosion sugarcane bagasse is better than alkalized sugarcane bagasse.