改良双缩脲法快速测定肌肉蛋白质含量的研究

肌肉蛋白质含量测定一直沿用丹麦化学家凯氏(Johan Kjedahl)定氮法,并被列为AOAC的标准法。该法繁琐、费时,加上试剂和能源消耗多,工作量大,易产生测定误差。我们根据希夫氏原理,以氢氧化钾溶液直接水解肉样,并用改良双缩脲试剂显色,再以分光光度计比色定量测定蛋白质含量。     

饲料中粗蛋白质的快速比色测定

饲料中粗蛋白质的快速比色测定谭伟军（湖南益阳动物保健药品厂４１３００２）本文介绍一种简单、快速测定饲料中粗蛋白质的方法，该方法利用含氮化合物被强酸消化转变为硫酸铵，与氢氧化钾反应生成氢氧化铵，再与纳氏试剂中的碘化钾汞复盐形成棕黄色的碘化双汞铵，然后进...     

骨粉、磷酸氢钙中含磷量的测定方法

骨粉和磷酸氢钙在饲料工业生产中作为配合饲料的钙磷补充物使用量越来越大，目前生产厂家对其含磷量测定多采用ZBB46001－87和GB8258－87标准中的沉淀称重法，而测定配合饲料中的磷含量则采用GB6437标准的比色曲线法，两者测定原理有所不同。我们在实际检测中发现，沉淀称重法测定的磷值总是高于比色曲线法0．5％左右。为了避免因分析方法不同而带来的结果偏差和探索快速测定方法，我们在GB／T6437－92测定方法的基础上反复对比试验证明，采用比色对比法测磷，具有操作简便、结果准确、省时节约等优点。l原理、仪器设备、试剂与国标GB…     

应用氰化高铁法与沙利氏法测定血红蛋白含量的实验观察

血红蛋白含量(Hb)测定,是临床血液学中应用最广泛的检验项目之一。国内兽医界测定Hb多采用沙利氏酸化血红蛋白比色测定法(简称Sahli法),但因受多种因素的影响,其准确性很难令人满意。早在60年代,世界卫生组织已经推荐氰化高铁法(简称Hien法) 作为测定Hb的标准方法。自70年代以来,该法已被我国医院检验单位所采用,有准确性高、简单易行、稳定性好、重复性良好等     

炭疽Ascoli氏试验光电比色判断研究

炭疽Ａｓｃｏｌｉ氏试验光电比色判断研究金锋（贵州省思南县兽医卫生防检站５６５１００）在检验炭疽时，通常采用Ａｓｃｏｌｉ氏试验，这种特异性很高的试验往往因抗原浓度、温度、液体电解质等因素，加之肉眼观察的误差给反应结果的认定带来了困难，笔者采用了光电比色...     

三种方法测定绵羊血红蛋白含量的比较试验

对血红蛋白仪法、氰化高铁血红蛋白法和沙利氏比色法测定绵羊血红蛋白含量进行了比较试验，发现沙利氏目测法测定结果比血红蛋白仪法低５７．８ｇ／Ｌ，而氰化高铁血红蛋白法与血红蛋白仪法的结果仅相差５．７ｇ／Ｌ。     

三种方法测定绵羊血红蛋白含量的比较试验

对血红蛋白仪法、氰化高铁血红蛋白法和沙利氏比色法测定绵羊血红蛋白量进行了比较试验。结果表明沙利氏目测法测定结果比血红蛋白仪法低57.8g/L，而氰化高铁血红蛋白法与血红蛋白仪法的结果仅相差5.7g/L。     

火焰原子吸收光谱法测定鱼粉中铬

在GB13088—91中规定了饲料中铬的测定方法，该法是以干灰化法分解样品，在碱性条件下用高锰酸钾将灰分溶液中铬离子氧化为六价铬离子，再将溶液调至酸性，使六价铬离子与二苯卡巴肼生成玫瑰红色铬合物，进行比色测定。但该方法操作繁琐，干扰因素较多，并且如果饲料中掺入了皮革粉，则此方法的测定结果偏差较大，作者采用火焰原子吸收光谱法，并加入基体改进剂测定鱼粉中铬含量，经准确度与回收率试验，取得较好的效果。     

盖勃氏法测定乳脂应注意的问题

盖勃氏法测定乳脂应注意的问题河北省大曹庄农场乳品检查站郭新建盖勃氏法，是我国乳品行业常用于测定乳脂的方法之一。奶样多的单位，多用脂肪速测仪进行测试，但为了做对比或校正其准确性，仍然离不开盖勃氏法测试乳脂。实践证明，在用盖勃氏法测定乳脂时，应注意以下几...     

氯离子选择性电极法测定饲料中可溶性氯化物

利用氯离子选择性电极法测定饲料中可溶性氯化物,经过多次试验并与国标GB/T6439-1992测定饲料中可溶性氯化物方法进行比较,该方法快速、简捷、准确,所需仪器简单,操作方便。作一标准曲线方程可同时测定大量的饲料样品,值得推广。 一、仪器与材料 1.仪器:酸度计或电位计(精度0.1mv)、氯离子选择性电极、双盐桥甘汞电极、磁力搅拌器、50mL纳氏比色管等。 2.试剂及溶液:水为去离子水,试剂为分析纯。     

气相色谱法测定苜蓿青贮料中的有机酸

使用四甲基氢氧化铵/碘甲烷对青贮料浸出液进行甲酯化反应,采用程序升温的方法,同时测定青贮料中乳酸、乙酸、丙酸、丁酸的含量。结果表明:该方法分离效果好,各组分的回收率在97.8%～101.2%之间,重复性好,标准曲线线性关系良好R2=0.9990～0.9997,所以采用此方法测定苜蓿青贮料中有机酸是较为理想的方法。     

不同处理方法对稻草感官品质及主要营养成分的影响

旨在研究不同处理方法对稻草感官品质及营养成分的影响。选用优质干稻草,分别用氢氧化钠、尿素、碳酸氢铵、纤维素酶处理,并取相同重量的原稻草,不进行处理作为对照组。结果表明,处理20 d和40 d后,各组稻草感官品质无明显差异（P〉0.05）,氢氧化钠组稻草呈浅黄色,草香味,质地柔软;尿素组稻草呈金黄色,氨味（放氨后有糊香味）,质地柔软;碳酸氢铵组稻草呈浅黄色,氨味,质地柔软;纤维素酶组稻草呈浅黄色,酸香味,质地柔软。稻草处理20 d后,与对照组相比,各处理组CP、EE、Ash、Ca、TP无显著性差异（P〉0.05）;稻草处理40 d后,与对照组相比,尿素组CP提高了8.86%（P〈0.05）,尿素组和碳酸氢铵组中CP显著高于其他组,其他养分各组间无显著差异（P〉0.05）。稻草经氢氧化钠、尿素、碳酸氢铵、纤维素酶等处理后,可以不同程度地改变稻草的物理特性和营养价值。从感官品质、主要营养成分以及成本来看,尿素和碳酸氢铵处理较经济实用,有利于在生产中推广;而酶处理目前由于成本较高,还有待于进一步研究。     

Effects of ammonium hydroxide treatment on the in vitro dry matter digestibility and gas production of wheat straw, sugarcane bagasse medium and konara oak rotted by edible basidiomycetes

Wheat straw, sugarcane bagasse medium and konara oak logs used to cultivate edible basidiomycetes were treated with ammonium hydroxide to investigate the relationship between the degree of rotting and the effect of ammonium hydroxide treatment on digestibility. Wheat straw was sampled before inoculation and on days 67 and 97 after inoculation with Pleurotus salmoneostramineus. Similarly, bagasse media were sampled before inoculation and on days 47 and 96 after inoculation with Pleurotus abalonus. Konara oak logs were sampled before inoculation and at 2 and 4 years after inoculation with Lentinula edodes. Aliquots of the samples were treated with ammonium hydroxide (NH₄‐N, 3% dry matter) at 45°C for 10 days. Ammonium hydroxide treatment increased the in vitro dry matter digestibility (IVDMD) and gas production (IVGP) of all the samples, except the konara oak samples collected before inoculation. The degree of increased digestibility was largest for the samples collected after short cultivation periods, followed by those collected after long cultivation periods and those collected before inoculation. However, the IVDMD and IVGP values after short cultivation periods were lower than those after long cultivation periods. Ammonium hydroxide treatment is effective at improving the digestibility of white‐rotted materials, although the effect is lessened as rotting proceeds.     

氢氧化锌制备饲料级氧化锌的新工艺研究

采用锌粉法保险粉的副产氢氧化锌为主要原料,和碳酸氢铵一步法合成碱式碳酸锌,850℃热分解碱式碳酸锌制得饲料级氧化锌。通过正交试验,考察了合成碱式碳酸锌的各种影响因素,得出最优工艺条件为:碳酸氢铵与氢氧化锌的摩尔比0.5,反应时间4h,反应温度30℃。同时还对制备的饲料级氧化锌样品与普通产品的性能进行了对比测试。试验结果表明,试验样品能提高饲料级氧化锌的分散性和比表面积,减小堆积密度,产品有助于改善预混合饲料的混合均匀度,在饲料工业上具有实际应用意义。     

Preparation and identification of aflatoxin B2a under laboratory conditions

The method of preparing and identifying small quantities of aflatoxin B2a after Pohland et al. (1968) was verified as it was necessary to differentiate various types of aflatoxins in analytic practice. Aflatoxin B2a was prepared by the hydroxylation of aflatoxin B1 in acid medium and was identified by thin silica gel layer chromatography (TLC) and by spectral analysis in methanol medium and in a mixture of methanol with ammonium hydroxide (14 + 1). The results of both methods of identification were in keeping with the results of earlier works. At TLC in the system of chloroform + methanol (95 + 5) the Rf values were as follows: Rf AFB1--0.68 and Rf AFB2a--0.32; in the system of chloroform + acetone + isopropyl alcohol (85 + 10 + 5) the respective values were Rf AFB1--0.46 and Rf AFB2a--0.22. Spectral analysis demonstrated a shift in the absorption maximum in the methanol + ammonium hydroxide medium from 362 nm to 404 nm in aflatoxin B2a. The yield rate of AFB2a was about 50 to 55%.     

Enhancement of beef chuck and loin muscles with ammonium hydroxide and salt

The objective of this study was to evaluate the tenderness of beef chuck and round muscles when enhanced with ammonium hydroxide and salt at different pump levels. A randomized, complete block design of 4 treatments and 3 muscles with 3 replications was used, with a total of 15 subprimals per treatment. Treatments included a 0% (CON), 15% (T15), 22.5% (T22), and 30% (T30) target pump. The triceps brachii (TB), biceps femoris (BF), and rectus femoris (RF) muscles were studied. Muscles were injected with a solution of ammonium hydroxide and sodium chloride (patent-pending technology from Freezing Machines Inc., Dakota Dunes, SD). Individual steaks were cut to a thickness of 2.54 cm, vacuum-packaged in trays, and frozen. Warner-Bratzler shear force, pH, and sensory evaluations were determined. Shear force decreased as the target pump percentage increased for all muscles (P < 0.050): TB = 39.9, 35.1, 32.1, and 27.0 N; BF = 39.4, 26.2, 23.3, and 19.3 N; RF = 42.7, 32.9, 30.7, and 28.9 N for CON, T15, T22, and T30, respectively. In all cases, there were no shear force differences between T15 and T22 (P > 0.050). As percentage pump increased, pH increased. The ultimate pH was moderately strongly to strongly related to shear force (r = 0.55, 0.70, and 0.80 for RF, TB, and BF, respectively). Trained taste panel ratings revealed an increase in tenderness, decrease in connective tissue, and an increase in juiciness as pump level increased for all muscles. In all cases but one (juiciness of the RF), the CON had the least desirable ratings and shear force values (P < 0.050). There were no major differences between T15 and T22, and T30 steaks tended to have an uncharacteristic soft and mushy texture. For this reason a 20% target pump level was determined to be the optimum pump level. These data suggest that adjusting pH in beef with ammonium hydroxide and salt can increase tenderness in muscles from the beef chuck and round. Any level of treatment was beneficial, with the greatest shear force benefit occurring in muscle pumped to 30%.     

Development of a Delayed-Type Hypersensitivity (DTH) Model in the Cynomolgus Monkey

Although a T-dependent antibody response (TDAR) assay is generally recommended as the first-line immune function assay in nonclinical immunotoxicity evaluation, second-line assays such as delayed-type hypersensitivity (DTH) to measure cell-mediated responses can provide helpful additional information. In this study, male Cynomolgus monkeys were injected intramuscularly either once or twice with 1 mg Keyhole Limpet Hemocyanin (KLH) or twice with a commercially available tetanus vaccine (40 IU tetanus toxoid + 0.06 mg aluminum hydroxide). All animals were subsequently challenged by intradermal injections of the same antigen or aluminum hydroxide after 4, 6 and 8 weeks. Clinical reactions at the injection sites were scored 24, 48 and 72 h post challenge. Skin biopsies were taken on completion of the observation period after each challenge for standard histological examination and immunolabeling using CD3 (T lymphocytes), CD19 (B lymphocytes) and CD68 (macrophages) antibodies. Tetanus toxoid induced stronger clinical reactions than KLH, whereas aluminum hydroxide induced no clinical reaction. Perivascular mononuclear cell infiltrates, a histopathological finding consistent with a DTH reaction, were seen after all challenges with tetanus toxoid or KLH, but not with aluminum hydroxide. Immunohistochemistry evidenced the presence of T lymphocytes and macrophages within these infiltrates. These results suggest that tetanus toxoid adjuvanted with aluminum hydroxide can induce a consistent DTH response for use as a model of cell-mediated response in Cynomolgus monkeys.     

甲酸-氢氧化钾/碳酸钾混合溶液法制备二甲酸钾

采用氢氧化钾、碳酸钾混合溶液与甲酸反应,一步制备获得二甲酸钾。相比传统的甲酸-氢氧化钾法,该方法能有效降低反应的剧烈程度,使反应可控。与甲酸-碳酸钾法相比,则可适当控制产气量,缩短反应周期。结果表明,反应温度65℃,反应时间1.5h,原料配比n(HCOOH)/n(K+)为2.6,混合比例n(KOH)/n(K2CO3)为0.3/0.7,此时收率可达89.08%。对蒸馏步骤进行优化后,在蒸馏压力为0.45MPa的情况下,控制蒸馏温度为95℃,采用母液回用,收率达到96%以上。     

The Purification and Concentration of Hog Cholera Virus

Partial purification of hog cholera virus (HCV) using a simple batch-type chromatographic procedure with magnetic ferric oxide (MFO) is described. Infectious HCV was adsorbed from isotonic solutions to MFO and was eluted under conditions of low ionic strength and high pH. Aqueous solutions of 0.01 M sodium cyanide or 0.0003 M ammonium hydroxide effectively dissociated MFO-HCV complexes. The data indicate that 50 to 100% of the original HCV infectivity was recovered concomitant with a 90 to 95% reduction of extraneous organic nitrogen.

MFO-purified HCV was concentrated by density gradient type centrifugations in buffered solutions of cesium chloride and sucrose. Prolonged isodensity centrifugations of concentrated MFO-purified HCV indicated a buoyant density of 1.14 to 1.15 gm/ml for the strain of virus used.

     

不同化学处理对稻草体外发酵动态变化的影响

采用瘤胃体外发酵技术评定了不同化学处理对稻草体外发酵特性的影响。试验以3头装有永久性瘤胃瘘管的荷斯坦奶牛为瘤胃液供体,用复合碱、氨及尿素处理稻草后,称量1 g样品于含有10 mL瘤胃液和90 mL培养基的39℃发酵瓶内体外发酵,分别于24,48,72,96 h冰浴终止发酵,测定产气量、发酵液中挥发性脂肪酸、氨态氮及微生物蛋白浓度。结果表明,化学处理提高了稻草发酵的产气量、挥发性脂肪酸、氨态氮以及微生物蛋白浓度。其中复合碱处理组的发酵速度最快,累计产气量、干物质消失率和挥发性脂肪酸浓度最高,显著高于其他各组,其次为尿素处理组和氨化处理组,对照组最低;尿素处理组的pH、氨态氮浓度和微生物蛋白含量最高,显著高于其他各组,氨化处理组和碱化处理组次之,对照组最低。化学处理提高了稻草的体外降解率,其中复合碱化处理的效果最好。