市售8种木聚糖酶酶学性质研究

本实验研究了市售8中国内外知名品牌木聚糖酶产品的耐热性、耐胃蛋白酶性以及胰蛋白酶性。研究结果表明:液体发酵所得木聚糖酶产品比固体发酵所得木聚糖酶产品耐热性强;胰蛋白酶对木聚糖酶活性影响较小;胃蛋白酶会破坏木聚糖酶的活性。同时,不同来源的木聚糖酶对胃蛋白酶的抵抗力也有一定的差异。因此,饲用木聚糖酶的耐热性以及对胃蛋白酶的耐受性也是评价其饲用价值的重要指标之一。     

饲用酶制剂中木聚糖酶酶学性质的研究

木聚糖酶是饲用酶制剂中的主要酶种之一,通过对某商品酶制剂中的木聚糖酶所进行的酶学性质的研究表明:该木聚糖酶的最适pH值为4.5,最适反应温度为50℃,干热稳定性良好,Cu2+、Zn2+、Mn2+和Fe3+对本木聚糖酶有抑制作用,而Mg2+、Na+及(NH4)2SO4能提高此木聚糖酶的活性。     

饲用酶制剂中木聚糖酶酶学性质的研究

木聚糖酶是饲用复合酶制剂中的主要酶种之一,本文对某商品酶制剂中的木聚糖酶进行了酶学性质的研究,这对于木聚糖酶的酶活测定、保存及应用均具有重要的指导意义.实验结果表明:该木聚糖酶的热稳定性良好,最适反应温度为50℃,最适pH为5.0,Km值为4.485 mg/mL,Cu2+、Zn2+、Mn2+和Fe3+对本木聚糖酶有抑制作用,而Na+、K+及(NH4)2SO4能提高此木聚糖酶的活性.     

饲用酶制剂中木聚糖酶酶学性质的研究

木聚糖酶是饲用复合酶制剂中的主要酶种之一，本文对某商品酶制剂中的木聚糖酶进行了酶学性质的研究，这对于木聚糖酶的酶活测定，保存及应用均具有重要的指导意义。试验结果表明：该木聚糖酶的热稳定性良好，最适反应温度为50℃，最适pH值为5．0，Km值为4．485mg/mL,Cu^2 ,Zn^2 ,Mn^2 和Fe^3 对本木聚糖酶的抑制作用，而Na^ ,K^ 及（NH4）2SO4能提高此木聚糖酶的活性。     

饲用酶制剂中木聚糖酶酶学性质的研究

木聚糖酶是饲用复合酶制剂的主要酶种之一，本文对某商品酶制剂中的木聚糖酶进行了酶学性质的研究，这对于木聚糖酶的酶活测定，保存及应用均具有重要的指导意义，实验结果表明，该木聚糖酶的热稳定性良好，最适反应温度为50℃，最适pH为5．0，Km值为4．485mg/mL,Cu^2 ，Zn^2 ,Mn^2 和Fe^3 对本木聚糖酶有抑制作用，而Na^ ,K^ 及（NH4）SO4能提高此木聚糖酶的活性。     

预消化法酶解饲用海藻粉中非淀粉多糖的初步研究

通过预消化法考查了纤维素酶、木聚糖酶、β-葡聚糖酶等非淀粉多糖酶对饲用海藻粉中非淀粉多糖的酶解情况。首先由单因素试验与正交试验确定了3种非淀粉多糖酶和中温淀粉酶酶解饲用海藻粉的最佳使用条件。其次通过评价试验证明3种非淀粉多糖酶对海藻粉均有较好酶解效果,还原糖增加率均达到10%以上。最后通过纤维素酶、木聚糖酶与中温淀粉酶的复合试验进一步发现,纤维素酶和木聚糖酶在酶解细胞壁中的非淀粉多糖时效果明显,其还原糖增加率最大可提高到50.9%。研究表明:非淀粉多糖酶可以有效地酶解海藻粉中难以被动物利用的非淀粉多糖,提高其营养成分的利用率。     

酶制剂活性的测定及稳定性的研究

试验在测定饲用纤维素复合酶活性的基础上,研究了不同的温度、金属离子和pH值对饲用纤维素复合酶稳定性的影响。从而得出,不同的温度、金属离子和pH值对饲用纤维素复合酶组分中的纤维素酶、β-葡聚糖酶和木聚糖酶的活性有着不同程度的影响。     

木聚糖酶、甘露聚糖酶体外酶解数据库的研究

模拟体内消化过程,考察木聚糖酶和甘露聚糖酶对各种饲料原料的降解效果,建立常用饲料原料的酶解数据库。实验在体外条件下,通过胃蛋白酶、胰酶和饲用酶三步消化结合透析法研究了外源木聚糖酶和甘露聚糖酶对各种饲料原料的酶解情况。结果表明,木聚糖酶和甘露聚糖酶对各种饲料原料的降解有明显的差异性。甘露聚糖酶对豆粕的降解效果明显好于其它原料,对棉粕的降解效果差。木聚糖酶对玉米、小麦和麦麸的酶解效果显著,对大豆和DDGS的酶解效果差。通过建立甘露聚糖酶、木聚糖酶与各种能量饲料间的酶解数据库,为针对不同饲料配方合理选择饲用酶制剂提供指导。     

体外酶解法评价饲用木聚糖酶的应用研究

在体外环境下,应用酶解法评价了来源不同的饲用木聚糖酶对不同饲料原料的作用效果。试验结果表明,4种酶中酶Ⅱ的作用效果最好。结果表明,体外酶解试验可以有效的评价饲用酶制剂的作用效果,为针对不同饲料配方合理选择饲用酶制剂提供指导。     

饲用酶制剂助力动物生产可持续发展

人类对动物蛋白需求量增加的同时也带来了对动物饲料需求的增加。植酸酶、木聚糖酶和蛋白酶是当今动物生产中使用最广泛的三种饲用酶。本文总结了三种饲用酶的主要作用方式和营养效能。     

木聚糖酶的研究进展及在生产上的应用

木聚糖酶作为一种饲料添加剂具有降低饲料粘度、提高营养物质利用率、提高机体免疫力、改善动物生产性能等作用,具有广阔的研究前景.本文从木聚糖酶的分子结构、理化性质、反应机理、应用及展望等方面进行综述.     

4种芽孢杆菌来源木聚糖酶基因在大肠杆菌中的表达及酶活分析

研究旨在比较4种不同来源木聚糖酶基因在大肠杆菌E.coli BL21中表达后的酶活等性质,为生产中筛选高表达量及耐极性木聚糖酶基因提供依据。根据已发表的木聚糖酶基因序列设计引物,分别扩增出浸麻芽孢杆菌(B.macerans)B3、地衣芽孢杆菌(B.licheniformis)B6、蜡样芽孢杆菌(B.cereus)B10和枯草芽孢杆菌(B.subtilis)B12的木聚糖酶基因片段,经克隆表达后获得4种工程菌。经培养和IPTG诱导后进行SDS-PAGE电泳检测及酶特性分析。测序结果表明,4个基因的开放阅读框均为642 bp。其中前3种木聚糖酶基因均为首次报道。4种重组木聚糖酶在55℃下的酶活分别为:36.16、3.85、7.22、98.98 U/ml。4种重组木聚糖酶的最适反应温度均在50~60℃,且枯草芽孢杆菌木聚糖酶最为耐热。结果提示,枯草芽孢杆菌来源的木聚糖酶具有较高的酶活和较好的耐热性。     

Xylanase Inhibitors Affect the Action of Exogenous Enzymes Used to Supplement Triticum durum-Based Diets for Broiler Chicks

Diets containing low-quality durum wheat (716 g/kg) for production of pasta were used to feed male broiler chicks. The efficacy of xylanase supplementation and the impact of xylanase inhibitors on losses in exogenous enzyme activity were analyzed. Birds fed on the basal diet, not supplemented with recombinant xylanases or Roxazyme G, reached a BW of 1,509 g with a feed conversion ratio of 1.77 at d 28. Growing performance was above that expected for the breed used, whereas feed conversion ratios were relatively higher. None of the 3 xylanase preparations under analysis affected growing performances and feed efficiency of broiler chicks. The activity of feed xylanases was considerably reduced in the presence of durum wheat extracts. The results suggest that reduction of exogenous enzyme activity was due to the action of durum wheat xylanase inhibitors and not to proteolysis.     

小麦型日粮中添加木聚糖酶对肉鸭生产性能的影响

本试验在小麦型基础日粮中分别添加木聚糖酶0、50、100、150、200g/t饲料(5000U/g酶)饲喂12日龄樱桃谷肉鸭,观察木聚糖酶对肉鸭生产性能的影响。结果表明:添加木聚糖酶对肉鸭生产性能影响不显著(P0.05),单位增重饲料成本以添加量50 g/t(即每1 kg饲料含250 U木聚糖酶)的有效含量为佳。     

德国牧羊犬,中国地方狼犬及其杂种耐热性能观察

试验观察测定了德国牧羊犬(原种犬和纯繁犬各6头)、中国地方狼犬(2头)、德×中杂一代(5头)和级进二代(4头),在炎热季节里的体温、呼吸频率、采食量、饮水量、血液生理指标和行为等方面的变化。结果发现,纯繁德国牧羊犬的体温显著高于中国地方狼犬和杂一代(P<0.05);高温对纯繁德国牧羊犬采食量的影响显著高于中国地方狼犬和杂一代(P<0.05);其他方面,纯繁德国牧羊犬的应激反应也较中国地方狼犬明显。初步表明,中国地方狼犬和杂一代的耐热性较强,纯繁德国牧羊犬的耐热性较弱,级进二代的耐热性较杂一代有所下降。     

屎肠球菌及其微生态制剂的研究进展

屎肠球菌作为一种潜在的新型饲用抗生素替代品,具有耐热、耐胃酸、耐胆盐、粘附力强、抑菌性和抗生素耐受性等优良的生物学特性,还能提高饲料的转化效率,增强动物机体的免疫力,降低腹泻率及死亡率,从而改善动物产品品质,屎肠球菌微生态制剂在畜禽养殖业中应用已十分广泛。其中微囊化屎肠球菌活菌制剂更是近几年的研究热点,其抗逆性强、稳定性高,可以作为饲用高活性微生态制剂应用于实际生产。本文主要阐述屎肠球菌的生物学特性及其在饲用微生态制剂中的研究进展。     

应用琼脂扩散法测定饲料中木聚糖酶含量

本实验研究了应用琼脂扩散法测定饲料中所舍木聚糖酶的活性.结果表明,该方法标准曲线制作线性良好;应用淀粉稀释木聚糖酶进行验证性实验,检测酶活测定值和实际理论值之间差异不显著(P>0.05),说明该方法准确率很高;应用饲料稀释木聚糖酶进行验证性实验,检测酶活值低于理论值,但这并不影响该方法对饲料中酶活的判定.综合整个实验结果表明,此方法可以很好的检测饲料中含有的微量木聚糖酶.     

Influence of particle size and xylanase supplementation on the performance, energy utilisation, digestive tract parameters and digesta viscosity of broiler starters

1. The aim of the present experiment was to examine the influence of particle size and xylanase supplementation on the performance, energy utilisation, and gross morphological and histological parameters of the digestive tract of broiler starters fed wheat-based diets. The experimental design was a 2 x 2 factorial arrangement of treatments evaluating two wheat particle sizes (medium and coarse) and two levels of xylanase supplementation (without or with 1000 xylanase units/kg diet). The two particle sizes were achieved by grinding the whole wheat in a hammer mill to pass through 3 and 7 mm screens, respectively. Broiler starter diets, based on wheat and soybean meal, were formulated and each diet was fed ad libitum to 6 pens of 8 male broilers each from d 1 to 21 post-hatch. 2. Wheat particle size had no effect on the performance of broilers. Xylanase supplementation had no effect on weight gain and feed intake. However, a significant particle size x xylanase interaction was observed for feed per unit gain with xylanase lowering feed per gain only in the coarse particle size diet. Xylanase supplementation improved the nitrogen-corrected apparent metabolisable energy at both particle sizes. 3. Xylanase supplementation decreased the relative weight and relative length of all gut components. Villus height and crypt depth and total extent of the mucosal layer were unaffected by both wheat particle size and xylanase supplementation. 4. The apparent viscosity of intestinal digesta, determined over the physiological range of shear rates, was not influenced by xylanase addition or particle size. 5. The findings of this study suggest that the effectiveness of exogenous xylanase in broiler diets is influenced by wheat particle size.     

耐碱性短小芽孢杆菌木聚糖酶在枯草杆菌中的表达及发酵条件优化

研究耐碱性短小芽孢杆菌木聚糖酶在枯草芽孢杆菌中异源表达。从耐碱性木聚糖酶高产短小芽孢杆菌BYG5-20中克隆得到带有自身启动子的木聚糖酶基因xynA,将其构建在大肠杆菌-枯草芽孢杆菌穿梭载体pGJ148中得到重组质粒pGJ148-xynA。采用电转化法将重组质粒pGJ148-xynA转入枯草芽孢杆菌1A747中,得到重组菌B.GJ148-xynA,然后进行诱导表达以及培养基的优化。重组菌GJ148-xynA发酵上清液中木聚糖酶酶活可达93.32IU/ml。耐碱性短小芽孢杆菌木聚糖酶基因xynA可以在枯草芽孢杆菌中实现异源表达,为枯草芽孢杆菌木聚糖酶分泌表达系统的进一步优化奠定了基础。     

Dynamic responses of cattle to thermal heat loads

The focal point of this limited review is bioenergetic research conducted in the Biological Engineering Research Unit at the U.S. Meat Animal Research Center (MARC), using recently developed instrumentation and analytical techniques. The dynamics of observed thermoregulatory responses in cattle to thermal heat load challenges are explored, with an emphasis on physiological and behavioral parameters of body temperature, respiration rate, and feed intake. Observations of body temperature, especially tympanic temperature, have shown hot environments to cause phase shifts, increased amplitude, and increased means for diurnal rhythms. Fractal analysis of body temperature records obtained at 2- to 10-min intervals has been found to be robust for objectively differentiating among responses of cattle in cool to hot environments, and it indicates a stress threshold of approximately 25 degrees C (coincident with declining feed intake). Other analyses determined a 21 degrees C threshold for increased respiration rate. The reported observations and analyses provide further understanding of how and why the animals respond to environmental challenges, an understanding that is necessary for refining performance models and developing energetic and thermoregulatory models. The dynamic responses are discussed in the context of establishing criteria for proactive environmental management for cattle during hot weather, using heat waves as an example.