| 摘要: |
| 【目的】筛选玉米 豆粕型饲料非淀粉多糖（NSP）酶谱，并对其酶解条件进行优化，以增加饲料中低聚糖的含量，获得具有抑菌特性的酶解产物，同时提高饲料的体外干物质消化率（IVDMD）。【方法】以还原糖含量为评价指标，通过L18(37)正交试验,研究不同用量5种NSP酶（纤维素酶110，220和330 U/kg，木聚糖酶176，352和528 U/kg，果胶酶331，662和993 U/kg，β-葡聚糖酶124，248和372 U/kg，β-甘露聚糖酶83，166和249U/kg）组合对玉米-豆粕型饲料的酶解效果，筛选最佳酶谱。探讨酶解温度（35，45，55，65 ℃）对饲料还原糖含量的影响，以及酶解时间（0，3，6，9，12，15，18，21，24 h）对饲料糖组分、抑菌效果、IVDMD的影响，确定最佳酶解条件。根据上述优化条件制备酶解饲料，将其与普通饲料及添加质量分数0.05%和0.10%防霉剂的饲料加入一定比例水后于25 ℃条件下进行贮存试验，比较各类饲料的抑菌效果。【结果】5种NSP酶的最佳配比为纤维素酶110 U/kg，木聚糖酶528 U/kg，果胶酶993 U/kg，β-葡聚糖酶372 U/kg，β-甘露聚糖酶249 U/kg。最佳酶解温度为55 ℃，此条件下饲料中的还原糖得率最高，可达17.98 mg/g。最佳酶解时间为15 h，此时酶解产生的低聚糖含量为78.65 mg/g，酶解产物对大肠杆菌的抑菌能力最强，同时对蜡样芽孢杆菌、沙门氏菌、植物乳杆菌等食源性致病菌也有明显的抑制作用；饲料IVDMD随酶解时间的延长呈升高趋势，15 h后基本达到平衡，为54.25%～56.25%。饲料贮存试验结果显示，普通饲料及添加0.05%防霉剂饲料在特定条件下放置2 d开始出现表观腐败现象，添加0.10%防霉剂组饲料和酶解饲料未出现表观腐败现象；酶解饲料中的细菌总数和大肠杆菌数均明显低于普通饲料和添加防霉剂饲料，但其对青霉菌无抑制作用。【结论】获得了玉米-豆粕型饲料的NSP酶解的酶谱及优化条件，NSP酶解能够显著提高玉米-豆粕型饲料的IVDMD，增加低聚糖含量，提高饲料的细菌抑制能力。 |
| 关键词: 玉米-豆粕型饲料 非淀粉多糖酶 酶解条件 体外干物质消化率 |
| DOI： |
| 分类号: |
| 基金项目:国家重点研发计划项目（2018YFD0500600）；重庆荣昌农牧高新技术产业研发专项（19254） |
|
| Pattern and optimal enzymolysis conditions of non-starch polysaccharide (NSP) enzymes in corn-soybean feed |
|
LIU Zhiyun,YANG Yemei,GUAN Xiaofeng,et al
|
| Abstract: |
| 【Objective】This study aimed to increase content of oligosaccharides,obtain enzymolysis products with antibacterial properties,and improve in vitro dry matter digestibility (IVDMD) of corn-soybean feed by screening enzyme patterns and optimizing enzymolysis conditions of non starch polysaccharide (NSP).【Method】The content of reducing sugar was used as the evaluation index.Five NSP enzymes with different contents (cellulose 110,220 and 330 U/kg,xylanase 176,352 and 528 U/kg,pectinase 331,662 and 993 U/kg,β-glucanase 124,248 and 372 U/kg,β-mannase 83,166 and 249 U/kg) were added into corn soybean feed to screen optimum enzyme pattern using L18(37) orthogonal design.The effects of temperature (35，45，55 and 65 ℃) on reducing sugar content,and time (0，3，6，9，12，15，18，21 and 24 h) on carbohydrate composition,antibacterial effect and IVDMD of feed were studied to obtain optimal enzymatic hydrolysis conditions.The enzymatic hydrolysis feed was prepared according to above optimized conditions.A storage test was carried out at 25 ℃ to compare antibacterial effects among ordinary feed,enzymatic hydrolysis feed and the feed with antiseptic (0.05% and 0.10% mass fraction).【Result】The optimum enzyme combinations were cellulose 110 U/kg, xylanase 528 U/kg,pectinase 993 U/kg,β-glucanase 372 U/kg and β-mannanase 249 U/kg in corn-soybean feed.The optimum temperature for enzymatic hydrolysis was 55 ℃ and highest reduction sugar yield (17.98 mg/g) was obtained.The optimum time was 15 h,at which the oligosaccharide content in enzymatic hydrolysis feed was 78.65 mg/g and enzymolysis products had the strongest inhibitory effect on Escherichia coli.Furthermore,it also showed inhibitory effects on foodborne pathogenic bacteria such as Bacillus cereus,Salmonella and Lactobacillus plantarum.The IVDMD of feed increased over enzymolysis time and reached almost equilibrium of 54.25%-56.25% at 15 h.Feed storage test showed that no spoilage was found in enzymatic feed and the feed with 0.10% mildew inhibitor,while ordinary feed and feed with 0.05% mildew inhibitor appeared rot after 2 days storage under certain conditions.The total bacterial plate counts and coliform counts in enzymatic feed were well below the counts in ordinary feed and feed with mildew inhibitor.Enzymatic feed was ineffective against blue mold.【Conclusion】The NSP enzyme pattern and optimal enzymolysis conditions for corn-soybean feed were obtained.The proper enzymolysis of corn-soybean feed by NSP enzyme can significantly improve IVDMD,content of oligosaccharide,and antibacterial ability. |
| Key words: corn-soybean feed NSP enzyme enzymolysis condition IVDMD |
