ELISA方法检测奶牛结核病的效果评价

牛结核病是由牛分枝杆菌(Mycobacterium bovis)引起的一种慢性消耗性人畜共患病.该病可通过排泄物及分泌物等进行传播,严重威胁畜牧业的发展及城乡居民的身体健康.为保障牛奶、牛肉等畜产品市场安全和人民生命健康安全,牛结核病的防控意义不言而喻.本文以PPD变态反应为检测标准,对ELISA检测结果进行评价,论述...     

Liver function of dairy cows in late pregnancy and early lactation

The possibility that alterations in liver function may occur during late pregnancy as well as after calving has been investigated in healthy dairy cows and the results compared with those from non-pregnant non-lactating cows. There were significant alterations in plasma total bilirubin, glucose, total ketone body and urea concentrations, in bromsulphthalein clearance and in plasma aspartate aminotransferase and creatine kinase activities in periparturient cows compared with non-pregnant non-lactating cows. Of these, only the alterations in glucose, ketone bodies and urea concentrations and bromsulphthalein half-time and retention were markedly different before calving. The degree of fatty infiltration of the liver was significant two weeks before as well as two weeks after calving which differed from previous reports. It seems likely that the changes in the liver in dairy cows are functional and reversible and related to the metabolic demands of late pregnancy and early lactation. The results suggest that such changes in the liver occur well before calving.     

Oxidative status during late pregnancy and early lactation in dairy cows

In the last few years, the detection of free radical damage and the body's defences against it have become increasingly important in clinical medicine as a complementary tool in the evaluation of metabolic status. The aim of this study was to evaluate, under field conditions, the anti-oxidant status of healthy cows during late pregnancy and lactation onset using two parameters: (1) plasma levels of malondialdehyde (MDA), a degradation product of lipid peroxidation, and (2) total antioxidant status (TAS). Results were compared with those obtained in another group of cows with lesser metabolic demands. We also investigated possible relationships between antioxidant status markers and other relevant blood parameters. Our results confirmed the characteristic metabolic changes associated with late pregnancy and early lactation. MDA and TAS provided an accurate reflection of the internal physiological status of the animal. The data indicated increased lipid peroxidation around parturition, but with wide individual variations that may be attributable not only to the physiological stage but also to unknown factors that will have to be further considered in future studies.     

Progesterone concentration in defatted milk of dairy cows in early pregnancy.

Progesterone concentrations have been measured in defatted milk of British Friesian cows of four herds during the oestrus cycles (other than short cycles) immediately before artificial insemination (AI) at oestrus and immediately after AI (in non-pregnant cows), and during early pregnancy. Differences in mean progesterone concentrations between herds were significant (P less than 0.05) on all days within the day 10-18 period after AI, both in pregnant and in non-pregnant, inseminated cows but were not significant between pregnant and non-pregnant cows within herds until day 17 or 18. It is concluded that up to this time (that of luteolysis in non-pregnant cows) undefined factors, variable among herds, can have a much greater influence on the rate of progesterone secretion by corpora lutea and consequent progesterone concentration in plasma and milk than does the presence of conceptuses. Maximum mean progesterone concentration reached during early pregnancy in two herds did not differ significantly; it was reached in the 11-15-day period in one herd but not until 46-50 days in the second. Mean progesterone concentration declined after day 90.     

Validation of a commercial ELISA for the detection of bluetongue virus (BTV)-specific antibodies in individual milk samples of Dutch dairy cows

A recently developed indirect ELISA for the detection of bluetongue virus (BTV)-specific antibodies in bovine milk samples was compared to that of the routinely used competitive ELISA on serum samples. During the bluetongue outbreak in the Netherlands in 2006, caused by BTV serotype 8, coupled serum and milk samples were obtained from 470 individual cows from 10 BTV-infected farms with an average seroprevalence of 57%. In addition, bulk milk samples of the same farms, and historically BT-negative samples were tested. Compared to the ELISA for sera, the relative specificity and sensitivity of the ELISA for milk samples is 96.5% and 98.9%, respectively when using a S/P% cut-off value of 50% as advised by the manufacturer. The optimal cut-off value was found at S/P% of 90% revealing an optimal specificity (99.0%) combined with an optimal sensitivity (98.1%). Titres in positive individual milk samples ranged from 1 to 2048 with a peak titre of 128. Bulk milk samples contained antibodies with titres ranging from 64 to 512. The ELISA for milk samples was found to be a reliable and robust test. This diagnostic tool is very useful, and may replace the ELISA for serum samples as first choice in order to get insight into the status of lactating individual animals and therewith of the entire herd with respect to BTV infection.     

Upregulation of interferon-stimulated genes and interleukin-10 in peripheral blood immune cells during early pregnancy in dairy cows

In cows, interferon-tau (IFNT) regulates maternal recognition around days 15-19 after artificial insemination (AI). The present study hypothesized that if key target genes of IFNT are clearly upregulated in earlier stages of pregnancy, these genes could be use as indices of future pregnancy in cows. Therefore, we determined the expression of these genes in peripheral blood mononuclear leukocytes (PBMCs) and polymorphonuclear granulocytes (PMNs) during the maternal recognition period (MRP). Twenty multiparous Holstein cows were subjected to AI on day 0 and categorized into the following groups: pregnancy (Preg, n = 9), embryonic death (ED, n = 5) and non-pregnancy (NP, n = 6). Progesterone levels in the Preg group were higher than those in the NP group on days 12-21. ISG15 and OAS-1 (IFN-stimulated genes: ISGs) mRNA in PBMCs on day 8 was higher in the Preg group than in the NP group, and these mRNAs in PMNs was higher in the Preg group on day 5 than in the NP and ED groups. Interleukin-10 (IL-10, Th2 cytokine) mRNA expression increased on day 8 in the PBMCs of pregnant cows. Tumor necrosis factor α (TNFα, Th1 cytokine) mRNA expression was stable in all groups. In an in vitro cell culture experiment, IFNT stimulated mRNA expression of ISGs in both PBMCs and PMNs. IFNT stimulated IL-10 mRNA expression in PBMCs, whereas IFNT increased TNFα mRNA levels in PBMCs in vitro. The results suggest that ISGs and IL-10 could be responsive to IFNT before the MRP in peripheral blood immune cells and may be useful target genes for reliable indices of pregnancy before the MRP.     

Evaluation of two cowside tests for the detection of subclinical ketosis in dairy cows.

The goal of this study was to evaluate the sensitivity and specificity of two cowside tests for subclinical ketosis in dairy cows. The tests utilize milk and urine samples, respectively. One hundred and eighty-five cows, one to sixty days postpartum, were sampled for milk, urine, and blood. Subclinical ketosis was defined with serum beta-hydroxybutyrate measurements. The sensitivity and the specificity of both tests at different beta-hydroxybutyrate levels were estimated. When subclinical ketosis was defined at beta-hydroxybutyrate levels of 1.4 mmol/L and higher, the milk test had sensitivity of 90% and specificity of 96%. The urine test lacked specificity (values < 67%), but sensitivity was 100% at beta-hydroxybutyrate levels of 1.4 mmol/L upward. Both the milk and urine test can be used to monitor subclinical ketosis in a herd. Milk testing is preferred, because of the easy obtainability of milk combined with the overall better test characteristics.     

The effects of early treatment for hindlimb lameness in dairy cows on four commercial UK farms

An 'early threshold' protocol for treating cows within 48h of being detected lame in one or more hind limbs at fortnightly mobility scoring was tested on a randomly selected group of cattle on four commercial dairy farms. The outcomes of the early threshold treatment for first cases of lameness were compared with those of the farmers' conventional approach to treatment. The early threshold schedule resulted in a much shorter time to treatment than the conventional approach, for which the median time from the cow first being scored lame to treatment was 65days. The early threshold group presented with less severe foot lesions and cattle were less likely to be selected for further treatments by the farmer than conventionally treated cows. Early threshold treatment reduced the prevalence of lameness 4weeks after treatment, compared with controls. A clear effect of the early treatment on milk yield was not detected.     

Variations in blood composition in dairy cows during pregnancy and after calving

The effects of pregnancy and of the onset of lactation on blood composition was studied in 21 Friesian cows. Among the 23 components studied only seven showed significant variations. Serum iron decreased at the end of pregnancy while creatinine increased throughout the last six months. There were decreases in blood glucose, cholesterol and alanine aminotransferase at the end of pregnancy. Triglycerides increased rapidly after drying-off and serum urea increased in the first month after calving.     

A decrease in blood beta-carotene in dairy cows during late pregnancy period

In four successive seasons of green and winter feeding in the years 1980-1984, beta-carotene concentrations were determined in the plasma of venous blood of 3441 cows in the first phase of lactation, in the other phase of lactation, in the eighth month of pregnancy and in the 9th-9.5th months of pregnancy. The cows in the other phase of lactation had the significantly highest beta-carotene concentrations in the two feeding seasons. In the eighth month of pregnancy there occurs a significant drop that continues also in the 9th-9.5th months of pregnancy. In the first phase of lactation beta-carotene concentrations remained at the level of the values from the 9th-9.5th months of pregnancy. In the period of winter feeding, the mean concentrations of beta-carotene in all groups of cows were deep below the limit value of 7.44 mumol . l-1, which indicated that it was necessary to fortify feeds with vitamin A; in the cows in the 9th-9.5th months of pregnancy and in the cows in the first phase of lactation they were lower than the critical value of 5.58 mumol.l-1, which signaled the disorders of reproduction processes. In the course of the years of investigation beta-carotene concentrations varied in the same manner in all groups of cows in keeping with the vegetation period of the feed, feed kind and quality.(ABSTRACT TRUNCATED AT 250 WORDS)     

同期发情处理的乏情奶牛血液病理学变化及其妊检阴性的风险预警

为了探究乏情奶牛同期发情处理前血浆生化指标的变化及对其输精后28 d妊检阴性(-)的风险预警意义,本试验在黑龙江省某集约化牛场选择了产后实施同期发情的奶牛共48头,根据试验奶牛产后40 d内是否发情分为发情组(E)23头和乏情组(A)25头,并对同期发情前试验牛进行血浆生化指标分析和输精后28 d妊检。结果显示:与发情奶牛相比,乏情奶牛血浆中孕酮(P_4)含量显著升高;雌二醇(E_2)、葡萄糖(Glu)、硒(Se)、牛组胺(HIS)、脑源性神经营养因子(BDNF)、牛组胺(HIS)含量显著降低。应用Pearson相关分析和二元Logistic回归模型确定了应用三针法前当奶牛血浆HIS含量 26.12μg/L,输精后28 d妊检为阴性(-)的风险增大;应用五针前当奶牛血浆中E_2含量46.45 pmol/L时,输精后28 d妊检为阴性(-)的风险增大。     

吸附ELISA检测奶牛副结核病

应用吸附ELISA对2批澳大利亚及1批新西兰进口奶牛进行副结核病的检测,结果2头阳性反应,其余为阴性反应。特异性试验和重复性试验表明吸附ELISA在进口奶牛副结核病的检测中,结果准确、特异性高、重复性好,且具有快速、灵敏、操作简单的特点,适合应用于大批量样品副结核病的检测。     

Comparison of four methods for detection of oestrus in dairy cows with resynchronised oestrous cycles

OBJECTIVE: To compare the sensitivity and positive predictive value of four methods for detection of oestrus in dairy cows with resynchronised oestrous cycles. PROCEDURE: Oestrous cycles in cows in three herds were synchronised for a first round of artificial insemination (AI) and then resynchronised for a second round of AI. Sensitivity and positive predictive value of four aids (pedometers, radiotelemetric transmitters [HeatWatch; HW], tail-paint and heatmount detectors) that were used to detect the resynchronised oestrus were compared. Milk progesterone concentration and pregnancy testing at 12 weeks were used as the reference standard for cows being in oestrus. RESULTS: The mean sensitivity and positive predictive value for detecting the resynchronised oestrus, for each aid that was used, was > 80%. Tail-paint was significantly more sensitive at detecting oestrus compared to heatmount detectors (P = 0.002), but not significantly more sensitive than pedometers (P = 0.07) or HW (P = 0.55) for detecting oestrus (91.3, 85.7; 81.4 and 88.4%, respectively). Positive predictive value of HW for detecting oestrus was greater than tail-paint (P = 0.014) and heatmount detectors (P = 0.024) but not pedometers (P = 0.25; 100, 91.7, 92.9 and 87.5%, respectively). Positive predictive value of heatmount detectors was greater than pedometers in herd C (93.4% vs 73.3%; P = 0.035) but not in herds A (95.0% vs 90.0%; P = 0.56) or B (90.8% vs 100%; P = 0.10). No other significant differences in sensitivity or positive predictive value of detection of oestrus were found between aids. CONCLUSION: Tail-paint, heatmount detectors, pedometers and HW provide a high sensitivity (> 80%) and positive predictive value (> 85%) of detecting oestrus in dairy cows with resynchronized oestrous cycles.     

Evaluation of four commercial serum ELISAs for detection of Mycobacterium avium subsp. paratuberculosis infection in dairy cows

During the first 3 months of 2006, a study was performed on four dairy cattle herds with a history of clinical paratuberculosis, to evaluate different enzyme-linked immunosorbent assays (ELISAs). Serum samples obtained from 326 animals were analysed using four ELISAs to detect antibodies to Mycobacterium avium subsp. paratuberculosis (MAP). Kappa (kappa) concordance coefficients in pairwise comparisons of the ELISA outcomes ranged up to 0.22 (linear kappa) and 0.25 (quadratic kappa). When the borderline positives obtained were considered as negatives, kappa values remained low (kappa up to 0.19). Having performed the serological tests, faecal samples were then obtained from 55 animals (including all animals testing positive in two or more ELISAs) from the same herds. Faecal culture and faecal polymerase chain reaction (PCR) for the detection of MAP were negative in all cases. The results indicate that neither the currently available serum ELISAs nor faecal culture and PCR are effective for the early detection of MAP in dairy cattle.     

荷斯坦奶牛妊娠早期血浆差异蛋白质组学研究

采用二维凝胶电泳(2-DE)结合MADIL-TOF-TOF串联质谱法对荷斯坦奶牛妊娠早期血浆进行蛋白质组学分析鉴定,发现了6种差异蛋白在妊娠后表达量上调,分别是凝集素1前体、转甲状腺素蛋白前体、3,5-二碘水杨酸络合的牛血清白蛋白的晶体结构的A链、白蛋白、未命名蛋白产物及结合珠蛋白-25同源物1前体。对这6种蛋白在不同时期含量的变化趋势及可能引起每种蛋白含量变化的原因和在妊娠过程中的功能进行了分析。     

Relationship between plasma progesterone and pregnancy-associated glycoprotein concentrations during early pregnancy in dairy cows

The relationship between the concentration of plasma progesterone (P4) during embryo attachment or at recognition of pregnancy, and that of pregnancy-associated glycoprotein (PAG) was assessed in dairy cows. The outcome of artificial insemination (AI) was classified as positive (AI+), negative (AI?), or late embryonic mortality (EM) by measuring circulating PAG concentrations and by ultrasonography. Based on P4 concentrations at either day 21 or day 15, AI+ and EM cows were classified into ‘low’ (P4 concentrations < mean) and ‘high’ (P4 concentrations > mean) P4 groups. In both experiments, the threshold of P4 concentration between the ‘low’ and ‘high’ groups was approximately 6 ng/mL. PAG concentrations were lower in the ‘low’ group only when P4 concentrations were below the threshold. The study findings suggest that a possible P4 threshold exists below which PAG secretion may be impaired.     

Oestrus prediction in dairy cows using an ELISA progesterone test

The commercially available test kit for assaying milk progesterone was used in the practice laboratory on samples taken daily from cows 17 to 24 days after service. Improved oestrus detection rates and accuracy were achieved by predicting the onset of oestrus. Similar results were obtained by sampling on days 18, 20, 22 and 24 or on days 19, 21 and 23 after service. Calving to conception intervals improved from 115 to 84 days in one herd and from 85 to 74 days in another and the potential economic benefits in these two herds outweighed the costs by 7.4:1 and 3.4:1, respectively.     

Serum paraoxonase activity in dairy cows during pregnancy

Preparturient dairy cows are at high risk of metabolic and reproductive disorders and oxidative stress is considered to be involved in these events. We investigated the serum paraoxonase activity in dairy cows during pregnancy and alterations in lipid and lipoprotein patterns in this period. The relation between paraoxonase activity and HDL-cholesterol concentration was also compared. The study was carried out on 76 pregnant lactating and 26 pregnant dry Holstein dairy cows. The serum paraoxonase activity was determined by the method of hydrolysing of paraoxon, while triglyceride, cholesterol and HDL-cholesterol concentrations were measured by the enzymatic kit methods. A significantly higher serum triglyceride concentration (P<0.001) was observed in dry cows compared to lactating cows. The total cholesterol and HDL-cholesterol concentrations were significantly lower (P<0.001) in dry cows than in lactating ones. In dry cows, paraoxonase activity was significantly lower than in those lactating (P<0.001). There was no significant difference in paraoxonase/HDL-cholesterol ratio between the investigated groups. It seems that the lower HDL concentration could be one of the causes of reduced paraoxonase activity considering the role of HDL as a carrier of most paraoxonase molecules in the blood. A decreased serum paraoxonase activity could diminish the effectiveness and total capacity of the whole antioxidative system during prepartum period in dairy cattle.