应用单胃动物仿生消化仪评价小麦日粮添加木聚糖酶效 果的可行性研究 摘要 本试验利用第三代单胃动物仿生消化系统(SDS-III)观测添加木聚糖酵后小麦体 外消化率的变化与酶添加量间的关系,并用肉鸡排空强饲法验证加_■饲料仿生消化 率变化规律的重现性。旨在探讨单胃动物仿生消化系统用于评价加酵飼料的可行性。 试验共分三部分。 试验一仿生消化系统运行稳定性及鸭饲料仿生法消化估测值的实验室间平 行性研究 按照SDS标准操作流程,利用经软件和硬件升级改造后的SDS和模拟消化液 标准试剂盒,在本实验室条件下测定了 18个批次玉米-豆粕标准样品的干物质消化 率,分析测定结果的批内、批间变异度,并与中国农科院动物营养学国家重点实验 室的测定结果进行了可重复条件下的实验室间重演性和精度比较。结果表明,同一 批次内DMD最大绝对差值幼.9%,批内变异系数<0.59%;不同批次间,DMD最大 绝对差值幻.3%,批间变异系数《0.57%;两种原料的总变异系数切.59%。不同实验 室间,批内变异系数幼.66%,批间变异系数幼.79%;实验室内变异系数<0.84%,实 验室间变异系数幺1.7%;总变异系数<1.9%。在本实验室对两种饲料标样分别进行了 15次重复测定,玉米和豆粕DMD的最大绝对偏差控制在0.6%、0.9%之内的概■率 >99% (P<0.01)。以上说明本试验所用的SDS在本实验室运行稳定,测定结果与国 内同类实验室的结果具有可比性。 试验二用仿生消化系统(SDS)评价小麦中添加木聚糖酶效果的研究 试验选取4个不同产地的小麦样品,分别添加0、500、2000、8000和12500 U/g 5个剂量的木聚糖酶,共20个供试样品。每个样品测定时,并做添加与不添加内源 消化酶2种处理方式,利用SDS-III测定各供试样品的DMD,比较木聚糖酶添加量、 小麦来源和内源消化酶添加与否对测定结果的影响,旨在探讨添加木聚糖酵对小麦 体外消化率的影响规律。结果显示,添加内源消化酶虽然极显著提高了 4个来源小 麦的DMD测值(尸<0.01),但对小麦DMD测定结果的变化规律均无影响,4个小麦 样品添加与不添加内源酶DMD测值间的回归系数分别为0.751、0.758、0.789、0.679, 回归显著性概率均达到极显著水平(PO.Ol)。4个来源小麦样品的DMD均随着木 应用单胃动物仿生消化仪评价小麦日粮添加木聚糖酶效果的可行性研究 聚糖酶添加剂量的升高表现先升高后降低的趋势,每个小麦样品DMD最高值与最 低值之间差异均达到显著水平(P <0.05 )。但4个来源的小麦样品DMD测值对木聚 糖酶添加量的反应并不同步(P<0.05),表现出明显的差异性。综上可见,小麦DMD 测值与木聚糖酶添加剂量间呈现非线性关系,即存在对应DMD测值最大的最适木 聚糖酶加入量;超量添力n木聚糖酶对小麦DMD测值可能产生负面影响,本文暂称 为“高剂量负效应”。同时,小麦DMD最大测值对应的最适木聚糖酶加入量还可能 随小麦来源(品种)而异。利用SDS研究DMD测值与木聚糖酵加入量间的关系可 能并不需要加入昂贵的内源消化酶。 试验三用排空强詞法测定添力p木聚糖酶对肉鸡小麦养分消化率的影响 试验采用排空强饲法研究木聚糖酶添加剂量与小麦养分体内表观代谢率变化规 律的关系,旨在验证试驗二中利用SDS-III测出的小麦DMD与木聚糖酶添加量间的“高 剂量负效应”是否在体内法中重现,并通过深入分析体内和仿生消化前后主要成分的 变化,解释引起“高剂量负效应”的可能原因。进一步验证SDS-III用于评价加酵祠料的 可行性。试验选用18周龄以上,体重2.5±0.2Kg,健康成年黄羽肉用公鸡48只,设木聚 糖酶添加量和小麦来源2个因子,每个因子含3个水平,其中3个小麦来源分别为选用 试验二中的1号、2号、4号小麦,酶的添加水平为0、2000、12500U/g,共9个处理。 实验分两批次测定,第一批次每个处理设8个重复,第二批次每个处理设10个重复, 每个重复一只鸡。按照排空强饲法操作流程收集试验个体粪样,并测定各试验鸡内源 消化剩余物中主要养分的变化。结果显示,除粗灰分外,添力口木聚糖酶对小麦其他营 养物质代谢率并无显著影响(P>0.05),剂量效应不显著。主要养分的体外消化率与体 内代谢率相关性分析结果表明,二者的干物质和粗蛋白消化率呈显著正相关(戶< 0.01 ),但灰分和非淀粉多糖消化率呈显著负相关(尸< 0.01 )。无论体外消化或体内代 谢,干物质和粗蛋白均是小麦的主要成分,二者体内消化率和体外代谢率间的高度正 相关说明,添加木聚糖酶后,小麦体外消化率的变化规律在体内代谢中有类似表现, 但小麦NSP和动物内源蛋白生成量可能掩盖了部分相似性。同时体内法结果变异度大 也可能是掩盖木聚糖酶添加剂量效应表现的重要原因之一。综上说明SDS体外法可以 反映日粮主要成分的体内代谢率,但受NSP和灰分等指标的干扰,还有待进一步研究 以提高准确度。 关键词:仿生消化系统;小麦;木聚糖酶;体外评价;干物质水解率 II 英文摘要-ABSTRACT THE FEASIBILITY OF USING BIONIC DIGESTION SYSTEM TO EVALUATE THE EFFECTS OF XYLANANSE SUPPLEMENTATIONIN WHEAT-BASED ABSTRACT The dry matter degradibilities of 4 wheat samples of different origins were measured using a Simulated Digestion System ( SDS-III) after adding different levels of xylananse. The In Vitro digestibilities wre compared with that of In Vivo ones, which were generated from male broilers following Fasting-Force Feeding procedure. The feasibility of the application of SDS-III system in evaluating the effects of xylanase in wheat-based diets were discussed according to the accordance of In Vitro and In Vivo results. Trail 1 The stability of bionic digestive system and its collaborator}; study on the enzymatic hydrolyzate gross energy of duck-feeds The dry matter digestibilities of 18 corn-soybean based duck diet samples, which were provided by Institute of Animal Science, the Chinese Academy of Agricultural Science (Beijing) for collaboratory studies, were determined in our laboratory according to the standardrised SDS operational procedure. The intra- and inter- batch variabilities were analysed according to the results obtained in our lab. The reproducibilities and precision of measurements were compared between our results and that of the Beijing parallel lab. The results showed that the maximum absolute difference of DMD measurements from the same instrument were not more than 0.9% and 1.3% for intra-batches and inter-batches, respectively, and that of variation coefficients for intra-bathes, inter-bathes, and total samples were not more than 0.59%, 0.57%, and 0.59%, respectively. The variation coefficients of intra-bath, inter-bath were not more than 0.66%, 0.79%,and that of intra-laboratory, inter- aboratory, and total measurements were not more than 0.84%, 1.7% and 1.9%, respectively. Fifiteen repeative measurements of each of 2 feed samples verified that 99% of DMD varation could be controlled within 0.6% and 0.9%. In in 应用单胃动物仿生消化仪评价小麦日粮添加木聚糖_效果的口J行性研究 summary, the SDS-III system was operating stablely in our laboratory.The results we got had a higher comparability with that of collab. Trial 2 Evaluation the dosage-response effects of xylananse in wheat using SDS-III system (in vitro) The wheat samples from 4 different origins were selected, and different levels of xylanase followed by 0,500, 2000,8000,and 12500 U/g were incorporated into the 4 cultivars, thus,forming 20 test samples. In addition, each sample was tested either withendogenous enzymes addition or not. The validated SDS-III system was applied to evaluate the effects of xylanase levels, wheat origins as well as endogenous enzymes on the DMD of all tested samples. The results revealed that although endogenous enzymes significantly increased the digestibilities of the four wheat cultivars (P<0.01), the trends of DMD varations were similar to that of no endogenous enzymes addition counterparts. The regression coefficients of DMD between the paired treatments of the four wheat cultivars were 0.751,0.758,0.789 and 0.679, respectively (P <0.01). The DMD of the four wheat cultivars all showed an increasing-then-decreasiing pattern as the elevation of xylanase activities. However, the DMD measurements differed significantly between the minimum and the maximum in each of the four cultivars (jP<0.05). But the most effective dosage of added xylanase on DMD in the four cultivars were not thesame (尸<0.05). In summary, there was a non-linear association between DMD of wheats and the levels of xylanase added, and there was an optimal level of xylanase that could achieve the best DMD in each wheat. According to the dose-response pattern, once the xylanase exceeded the optimal level, the xylanase would have a negetive effect on DMD. Hence,we proposed the effect as negetive response-to-high levels of xylanase. Meanwhile, the DMD measurements also affected by the cultivars of wheat. The results indicated that endogenous enzymes might not required for the evaluation of the effects of xylanase on DMD of wheats using SDS-III system. Trial 3 The effects of xylanaseon digestibilities of wheat-based diets