An improved polymerase chain reaction assay for the detection of Tritrichomonas foetus in cattle

An improved polymerase chain reaction test has been developed to detect Tritrichomonas foetus, the causative agent of trichomoniasis in cattle. The test amplifies a region of the 5.8S ribosomal RNA gene of T. foetus, and it is simple, sensitive, and specific when compared with traditional methods to examine field samples.     

The use of the cellulase digestion procedure for indexing the dry matter digestibility of forages

Abstract

The in vitro cellulase technique was compared with the rumen liquor technique and found to be more efficient for the indexing of the dry matter disappearance (DMD) of forages. A cellulase enzyme concentration of 80 IU/gDM gave a satisfactory linear regression y = l,3585x + 11,6250 (R² = 0,6453; P ≤ 0,01) for the estimation of in vitro digestibility (y) from cellulase dry matter disappearance (CDMD) (x).

Using the modified laboratory procedure developed, two operators can analyse over 100 samples, in duplicate, each week. Over a period of 18 months the technique was used to index the digestibility of forages from a wide variety of rangeland sites in Natal.     

An immunoblotting procedure for detection of antibodies against bovine leukemia virus in cattle.

A sensitive protein immunoblotting (Western blot) procedure has been developed for detecting anti-BLV antibodies in cattle sera. The antibodies against most of the major viral proteins could be detected. This procedure does not give any non-specific background staining and there is absence of any erroneous results due to utilisation of purified viral preparations. The procedure has been applied for detection of antibodies to BLV in a set of 74 sera samples and it has been compared with other commonly used serological tests like ELISA and agar gel immunodiffusion test.     

An improved microbiological procedure for detection of streptomycin residues in milk and animal tissues.

A method is described which allows detection of 0.025 µg streptomycin sulfate per ml. This represents an improvement of sensitivity by 8 times when compared with the currently used method. By adding penicillin to the assay medium in subinhibitory concentrations, a synergistic effect of streptomycin and penicillin is exerted towards the test organism, Bacillus subtilis, resulting in an increased sensitivity to streptomycin.     

Thiamine deficiency in a cat associated with the preservation of 'pet meat with sulphur dioxide

A cat with allergic dermatitis was fed a diet of fresh meat and a multi-vitamin supplement for 38 days to exclude food allergy as a cause of its dermatopathy. The cat died as a result of acute thiamine deficiency, which was caused by inac-tivation of thiamine by the preservative, sulphur dioxide. The continuing undeclared usage of sulphites in the Australian pet food industry is discussed.     

肉牛舍空气中氨气和二氧化碳含量四季变化的规律分析

为了解陕西省关中地区肉牛生产养殖环境状况和质量,从2017年3月10日至2018年1月31日,每隔10 d,7:00—19:00采用均匀布点方式对秦川公司(东西走向开放式牛舍)和秦宝公司(南北走向半开放式牛舍)肉牛场进行气体测定,分析氨气(NH_3)和二氧化碳(CO_2)的四季和日变化规律以及影响气体排放的气候因素。结果显示:NH_3和CO_2的排放具有一定季节性,秦川和秦宝牛舍CO_2浓度秋季最高,浓度分别为996. 41和1 126. 95 mg/m^3,冬季最低,分别为934. 03和968. 34 mg/m^3;在夏秋季节,秦宝牛舍的CO_2浓度极显著高于秦川牛舍(P>0. 01)。秦川和秦宝牛舍NH_3浓度春季最高,分别为3. 96和4. 71 mg/m^3,冬季最低,分别为2. 67和2. 44 mg/m^3;但全年2种牛舍的NH_3浓度差异均不显著(P>0. 05);在所有季节中,NH_3和CO_2含量都未超出国家标准。2种牛舍不同季节的CO_2日变化规律基本相同,均呈现出7:00、19:00高,13:00低的趋势,并且在所有季节,秦宝牛舍1 d中CO_2平均浓度都高于秦川牛舍CO_2平均浓度;在所有季节NH_3日变化中,2种牛舍NH_3浓度最低值都出现在7:00—9:00,而NH_3浓度最高值并未在不同季节表现出一致的变化规律,在春夏秋季为13:00和17:00浓度最高,在冬季,秦川牛舍为13:00 NH_3浓度最高,秦宝牛舍为11:00和17:00 NH_3浓度最高。综上所述,牛舍建筑类型和季节对规模牛场牛舍内的气体浓度有显著的影响。     

兽用消毒剂二氧化氯检测方法的研究进展

二氧化氯由于对细菌、病毒有广谱、快速、高效和安全的杀灭特点和优势,在畜禽养殖业中得到越来越广泛的应用。本文主要对目前国内外已有的二氧化氯检测方法进行阐述,并对各方法的优缺点进行评述。     

An improved TLC method for the detection of flunixin in equine serum

A method for flunixin detection in equine serum extracts involving thin layer chromatography, spraying the chromatogram with alkaline sodium hypochlorite solution and heating with a detection limit of 50 ng ml-1 is described.     

新疆牛双芽巴贝斯虫病的流行病学调查

本研究使用牛双芽巴贝斯虫HSP20（exon）-iELISA检测方法,对2006-2008年新疆14个地州市的牛双芽巴贝斯虫病流行病学进行了调查。结果显示：（1）新疆存在着牛双芽巴贝斯虫病,且比牛巴贝斯虫病严重。在2006年采集的278份牛血清样品中,阳性血清11份,感染率为5.40%。2007年的532份牛血清样品中检出阳性血清25份,感染率为4.70%。在2008年的530份牛血清中检出阳性血清53份,感染率为7.17%;（2）2008年,发病疫区内牛双芽巴贝斯虫感染率高达30%;（3）牛双芽巴贝斯虫感染的地州市由2006年的8个扩大到2008年的13个;（4）新疆牛双芽巴贝斯虫病的感染率逐年上升,疫区面积不断扩大,流行区内感染率激增。这是新疆首次利用血清学方法对全疆范围内牛双芽巴贝斯虫病进行大规模的流行病学调查。     

Establishment of a standard operating procedure for predicting the time of calving in cattle

Precise calving monitoring is essential for minimizing the effects of dystocia in cows and calves. We conducted two studies in healthy cows that compared seven clinical signs (broad pelvic ligaments relaxation, vaginal secretion, udder hyperplasia, udder edema, teat filling, tail relaxation, and vulva edema) alone and in combination in order to predict the time of parturition. The relaxation of the broad pelvic ligaments combined with teat filling gave the best values for predicting either calving or no calving within 12 h. For the proposed parturition score (PS), a threshold of 4 PS points was identified below which calving within the next 12 h could be ruled out with a probability of 99.3% in cows (95.5% in heifers). Above this threshold, intermitted calving monitoring every 3 h and a progesterone rapid blood test (PRBT) would be recommended. By combining the PS and PRBT (if PS ≥ 4), the prediction of calving within the next 12 h improved from 14.9% to 53.1%, and the probability of ruling out calving was 96.8%. The PRBT was compared to the results of an enzyme immunoassay (sensitivity, 90.2%; specificity, 74.9%). The standard operating procedure developed in this study that combines the PS and PRBT will enable veterinarians to rule out or predict calving within a 12 h period in cows with high accuracy under field conditions.     

牛皮蝇蛆病间接ELISA诊断方法的建立

以纹皮蝇Ⅰ期幼虫粗提蛋白为包被抗原,通过方阵试验确定了血清最佳稀释倍数为80倍,抗原最佳包被浓度为26.64μg/mL,并对其特异性、敏感性和重复性进行了试验,建立了牛皮蝇蛆病间接ELSIA诊断方法。再以建立的ELISA诊断方法对采自内蒙古地区的233份牛血清进行了检测。结果表明,所建立的牛皮蝇蛆病间接ELISA诊断方法具有较好的特异性、敏感性和可重复性,可用于牛皮蝇蛆病的血清学检测。     

An evaluation of genetic diversity indices of the Red Bororo and White Fulani cattle breeds with different molecular markers and their implications for current and future improvement options

The genetic diversity of the Red Bororo and White Fulani cattle breeds of Cameroon and Nigeria was assessed with a panel of 32 markers. Estimates for the various indices of genetic diversity, total number of alleles (TNA), mean observed number of alleles (MNA), mean effective number of alleles (MNE), observed heterozygosity (H _ob) and expected heterozygosity (H _ex), were higher at microsatellite loci than at protein loci. Mean H _ex values were above 71% at microsatellite loci in all the breeds and ranged from 37% to 41.6% at milk protein loci and from 40.9% to 45.6% at blood protein loci. The highest TNA and MNA of microsatellites were recorded for the Nigerian White Fulani. MNE of milk protein loci was highest in the Cameroonian Red Bororo, while TNA of blood protein loci was highest in the Cameroonian White Fulani. The high genetic diversity levels indicate the presence of the necessary ingredients for improvement breeding and conservation. Multi-locus estimates of within-population inbreeding (f), total inbreeding (F) and population differentiation (θ) of the breeds were significantly different from zero, except for θ of blood proteins. A high level of gene flow was found between the breeds (5.829). The phylogenetic relationship existing among the four breeds is greatly influenced by location. The high gene flow between the breeds may lead to a loss of genetic diversity through genetic uniformity and a reduction in opportunities for future breed development. We propose an improvement scheme with aims to prevent loss of genetic diversity, improve productivity and reduce uncontrolled genetic exchanges between breeds.     

Usefulness of a commercially available enzyme immunoassay for Shiga-like toxins I and II as a presumptive test for the detection of Escherichia coli O157:H7 in cattle feces.

The performance of a commercially available enzyme immunoassay (EIA) for determining the presence of Shiga toxin I and II in human diarrheal stool samples was evaluated for use as a presumptive test for the presence of Escherichia coli O157:H7 in nondiarrheal bovine fecal samples collected from 10 Kansas cow-calf ranches. The prevalence of E. coli O157:H7 in 2,297 samples, as determined by selective bacterial culture, was 1.6%. The sample prevalence of non-E. coli O157:H7 Shiga toxin-producing bacteria, as detected by the Shiga toxin EIA, was 5.8%. Only 2 of 136 samples that tested positive with the Shiga toxin EIA were positive for E. coli O157:H7 by culture. Compared with bacterial culture, the sensitivity of the Shiga toxin EIA was 5.5% and the specificity was 94.1%. Agreement between the 2 tests, as measured by the kappa statistic, was poor (kappa = -0.002). Although the Shiga toxin EIA was not a good presumptive test for the determination of E. coli O157:H7 in bovine fecal samples because of its low sensitivity (5.5%), it might be a useful test for the detection of Shiga toxin producing non-E. coli O157:H7 organisms in bovine feces.     

An evaluation of five serological tests for the detection of antibody to bovine herpesvirus 1 in vaccinated and experimentally infected cattle

More than 300 bovine sera from a previously reported vaccination and challenge trial were tested for antibodies to bovine herpesvirus 1 (BHV1) by five serological assays: enzyme-linked immunosorbent assay (ELISA) for IgM and IgG, passive haemagglutination (PHA), and two methods of virus neutralisation (VN). In a statistical comparison of ELISA (IgG), PHA and VN results, the assays showed highly significant correlations (P less than 0.01). The sensitivities of ELISA and 24-hour neutralisation tests were similar, in contrast to passive haemagglutination and one hour neutralisation which failed to detect BHV1 antibodies in some low titre sera.     

Radiometric pooled faecal culture for the detection of Mycobacterium avium subsp paratuberculosis in low-shedder cattle

OBJECTIVE: To identify the optimum pooling rate for pooled faecal culture (PFC) as a diagnostic tool in bovine Johne's disease control, for detection of cattle shedding low concentrations of Mycobacterium avium subsp paratuberculosis (Map). METHOD: Thirteen target animals were selected by delayed growth of Map from initial individual radiometric faecal cultures (first growth index at 5 weeks or later). A procedure based on radiometric culture and IS900 polymerase chain reaction and restriction endonuclease analysis confirmation was then used for PFC. RESULTS: Eight samples (stored for up to 17 months at -80 degrees C) yielded Map on subsequent culture, either from undiluted faeces or those mixed with normal cattle faeces at dilution rates from 1 in 5 to 1 in 50. From a regression equation, culture-positive animals were considered to be shedding relatively low levels of Map (< 6 x 10(4)/g of faeces). Pooling dilutions of more than 1 in 5 reduced PFC sensitivity. A minimum incubation period of 10 weeks at a dilution of 1 in 5 is recommended to detect such infected cattle. This pooling rate in radiometric culture is probably capable of detecting cattle shedding < or = 5 x 10(3) Map organisms/g of faeces, representing an estimated inoculum per culture vial of fewer than 20 viable organisms. CONCLUSION: Map was detected in more than 50% of the stored faecal samples from cattle shedding low concentrations of the organism. A pooling rate of 5 samples per pool is required to reliably detect infected low-shedder cattle using PFC based on radiometric culture.     

An enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies to bovine viral diarrhoea virus (BVDV) in cattle sera

A microtitre ELISA has been established for the quantitation of antibodies to bovine viral diarrhoea virus (BVDV). Single dilutions of sera were assayed and units of antibody were calculated from a standard curve. In order to detect the maximum number of responding animals both IgG1 and IgG2 antibody should be assayed, although detection of IgG1 alone was nearly as effective. The ELISA was as sensitive as the virus neutralization test for detection of antibody; comparison of an ELISA that detected IgG1 plus IgG2 antibody to BVDV with the virus neutralization test gave a correlation coefficient (r) of 0.89 (P less than 0.001 for 95 compared sera). Although similar amounts of IgG1 and IgG2 antibodies were present in sera from both experimentally- and naturally-infected cattle, antibody to BVDV in colostrum and in the sera from young calves was predominantly IgG1. The number of adult cows with antibody was 40 out of 41 while 36 of 44 calves reared in a beef unit were found to have produced antibody by the time they were 31.5 weeks old, an indication of the high prevalence of BVDV in the cattle population.     

Application of a radioimmunoassay for detection of the major internal antigen (p24) of bovine leukemia virus from cultured lymphocytes of cattle

A sensitive and specific radioimmunoassay for the major internal antigen of bovine leukemia virus has been applied to detecting this protein in cultured lymphocytes of infected cattle. The specificity inherent in this assay offers obvious advantages over a previously described syncytium induction assay for infectious bovine leukemia virus, because false positive reactions due to other viruses such as bovine syncytial virus are avoided. Investigations of various culture conditions indicated that maximal amounts of antigen had been produced after incubation for 72 hr at 37°C. Lymphocyte concentrations of 10⁶?5×10⁷ cells/ml gave satisfactory results. Tests of cultured lymphocytes from bovine leukemia virus infected or bovine leukemia virus-free cattle indicated a comparable sensitivity between the radioimmunoassay and syncytium induction assay in the detection of bovine leukemia virus infections.     

鸡血浆中磺胺氯吡嗪钠和甲氧苄啶含量HPLC检测方法的建立

建立了鸡血浆中磺胺氯吡嗪钠和甲氧苄啶含量测定的HPLC方法。对鸡血浆中磺胺氯吡嗪和甲氧苄啶采用乙腈提取和净化,梯度洗脱,高效液相色谱紫外检测法测定,外标法定量。流动相为甲醇-0.02 mol/L磷酸二氢钾水溶液。紫外测定时采用双波长检测:磺胺氯吡嗪检测波长为268 nm,甲氧苄啶检测波长为240 nm。空白血浆添加磺胺氯吡嗪和甲氧苄啶分别在0.1～70.0μg/m L和0.05～5.00μg/m L范围内线性关系良好(R~2均大于0.9999),磺胺氯吡嗪和甲氧苄啶的检测限分别为0.05μg/m L和0.025μg/m L,定量限分别为0.1μg/m L和0.05μg/m L。空白血浆添加磺胺氯吡嗪和甲氧苄啶在各自线性范围内,批内变异系数分别小于6.84%和7.55%,批间系数分别小于5.23%和6.81%。本研究建立的鸡血浆中磺胺氯吡嗪和甲氧苄啶的提取和净化方法,适用于鸡血浆中磺胺氯吡嗪和甲氧苄啶含量的单个或同时测定。     

An improved DNA-based test for detection of the codon 616 mutation in the alpha cyclic GMP phosphodiesterase gene that causes progressive retinal atrophy in the Cardigan Welsh Corgi

The aim of the study was to develop an improved test to detect the codon 616 gene mutation in the alpha cyclic GMP phosphodiesterase gene that causes progressive retinal atrophy in the Cardigan Welsh Corgi. We studied 10 control dogs of known genotype at codon 616 of the alpha cyclic GMP phosphodiesterase gene and 80 Cardigan Welsh Corgis of unknown genotype. A polymerase chain reaction (PCR) utilizing a mismatched primer was designed so that it introduced a HinfI restriction enzyme digestion site into the PCR product only if the normal gene sequence was present, the restriction site was not introduced if the codon 616 mutation was present. An additional HinfI site present in the amplified section from both normal and mutant alleles acted as a positive control for restriction enzyme digestion. The PCR reliably amplified a portion of the alpha cyclic GMP phosphodiesterase gene spanning the codon 616 mutation site. Restriction enzyme digestion with HinfI and analysis on a suitable agarose gel reliably ascertained the genotype of the control dogs and was used to identify the genotype of a further 80 test dogs. An improved DNA-based test for detection of the codon 616 mutation in the alpha cyclic GMP phosphodiesterase gene that causes progressive retinal atrophy in the Cardigan Welsh Corgi has been designed. This overcomes potential problems that could be associated with allele-specific PCR tests such as that used previously in a diagnostic test for this gene mutation.