Dual-label time-resolved fluoroimmunoassay for simultaneous quantification of haptoglobin and C-reactive protein in meat juice from pigs

A new method was developed to simultaneously measure 2 acute-phase proteins (APPs) by time-resolved immunofluorometry. The assay, based on double-label quantification of haptoglobin (Hp) and C-reactive protein (CRP) in meat juice samples from pigs, was constructed by use of a combination of europium and samarium chelate lanthanides as labels. Meat juice samples from 154 pigs were used for analytic and clinical validation of the assay through determination of precision, accuracy, limit of detection, and quantification. The analytic performance of the assay was satisfactory, with good intra-assay and interassay precision and accuracy. The levels of Hp and CRP were increased in the meat juice samples of diseased animals compared with healthy ones. According to the results, higher sensitivity could be achieved if the cut-off values of both proteins were taken into account for clinical relevance rather than used individually. Since the dual assay saved both time and sample, it could be used as a rapid and sensitive screening test in porcine production.     

Distribution of immunoglobulin isotypes and Salmonella antibodies in blood serum and meat juice of pigs

Using the close linear regression between the logarithm of the dilution degree of a sample and the logarithm of the extinction measured in an ELISA both the relative concentrations of immunoglobulines of the isotypes IgG, IgM and IgA and of the LPS antibodies against S. Typhimurium of the different isotypes in blood sera and meat juice of 15 slaughtered pigs were detected and compared. Furthermore the total concentration of antibodies against LPS of S. Typhimurium according to the "meat juice ELISA" were compared. Distribution of immunoglobulines between serum and meat juice revealed individual differences between the animals as well as between the different immunoglobulin-isotypes. Within the same isotype the ratio of the concentrations of anti-LPS Salmonella Typhimurium antibodies between serum and meat juice was significantly closer than relating the whole of immunoglobulines of the referred isotype. In order to detect pig herds with a high level of Salmonella exposure a comparison of the 1:30 diluted meat juice samples with the 1:400 diluted blood sera is justified, however, for detailed epidemiological or scientific studies there is a need to consider the existing differences between the immunoglobuline-isotypes as well as between the specificity of antibodies and of total immunoglobulines. While the concentration of Salmonella antibodies of the isotypes IgG1, IgG2 and IgA showed a clear and statistically significant correlation between both one below the other and with the total amount of Salmonella antibodies, this connection could not be established for the total amount of immunoglobulines of different isotypes and the IgM-antibodies.     

Risk factors for Salmonella infection in fattening pigs - an evaluation of blood and meat juice samples

The main objective of this study was to analyse potential herd-level factors associated with the detection of Salmonella antibodies in fattening pigs. Two independent datasets, consisting of blood and meat juice samples respectively, were used. Additional information about husbandry, management and hygiene conditions was collected by questionnaire for both datasets. The serological analysis showed that 13.8% of the blood samples and 15.7% of the meat juice samples had to be classified as Salmonella-positive. Logistic-regression models were used to assess statistically significant risk factors associated with a positive sample result. The results of the statistical blood sample analysis showed that the application of antibiotics increased the odds ratio (OR) by a factor of 5.21 (P < 0.001) compared to untreated pigs. A fully slatted floor decreased the prevalence of Salmonella as well as the use of protective clothing or the cleaning of the feed tube (ORs 0.35-0.54, P < 0.001). It was shown that a distance of less than 2 km to other swine herds increased the chance of a positive Salmonella result (OR = 3.76, P < 0.001). The statistical analysis of the meat juice samples revealed the importance of feed aspects. The chance of obtaining a positive meat juice sample increased by a factor of 3.52 (P < 0.001) by using granulated feed instead of flour. It also became clear that liquid feeding should be preferred to dry feeding (OR = 0.33, P < 0.001). A comparison of the blood sample analysis to the meat juice model revealed that the latter was less powerful because data structure was less detailed. The expansion of data acquisition might solve these problems and improve the suitability of QS monitoring data for risk factor analyses.     

Sampling plan for the establishment of a serologic Salmonella surveillance for slaughter pigs with meat juice ELISA

The guidelines of the German Ministery of Food, Agriculture and Forestry outlining a Salmonella surveillance programme, "Leitlinien für ein Programm zur Reduzierung des Eintrags von Salmonellen durch Schlachtschweine in die Fleischgewinnung" (February 5th, 1998), provide a staggered spot-check size depending on the annual production of slaughtery pigs. A classification of farms into three quality categories (< 20%, 20-40%, and > 40%) is performed by salmonella antibody levels detected in meat samples using ELISA. Beside a fundamental inquiry into the salmonella status, the programme ought to lead to a decreased burden on slaughtery pigs and finally to a reduced salmonella entry into meat handling and processing companies. The spot-check plan is based on an unfavourable initial position and does not consider the real situation of salmonella load in pig fattening farms. For many farms the procedure will lead to an unjustified expenditure of examinations. In simple model calculations it is shown how a significant reduction of testing amount can be reached and statistical reliability is guaranteed, too. At the same time, we attempt to find a compromise between optimal spot check size and practicability. For reasons of free enterprise, an additional category would be desirable containing farms without any positive antibody titres in the samples. The results achieved so far indicate that a large number of German slaughter pig producers would fall into this category, without the necessity of a higher examination effort.     

Chemiluminescent immunoassay as a microtiter system for the detection of Salmonella antibodies in the meat juice of slaughter pigs

Chemiluminescent immunoassay (CLIA) was applied in the screening of swine meat juice samples obtained from different laboratories in Germany, using the indirect enzyme linked immunosorbent assay (ELISA) as test for comparison. Out of the 1350 samples tested, 987 were found acceptable for validation of results. A good level of agreement between the two tests was obtained with a kappa value of 0.824 at 20% cut-off and 0.798 at 40% cut-off. At 20% and 40% cut-off levels, a sensitivity of 96.2% and 97.3%, respectively, and a specificity of 94.6% and 95.1%, respectively, were demonstrated between CLIA and ELISA. The detecting lipopolysaccharide (LPS) antigen was tested for specificity and a cross-reaction with two Escherichia coli and Yersinia strains was found when tested with ELISA. This reaction was not observed in CLIA, possibly because of the broader measurement spectrum of this test, which allows a more distinctive definition of immunologic reactions. The same explanation can be given for the increased number of meat juice samples which were positively detected only in ELISA but not in CLIA. Because of the wide detection range in CLIA, a normalization scheme was necessary to obtain reproducible results in this test system. The samples positively classified in screening were further tested for reciprocal titres in both test systems, and a higher correlation between screening and titration results was obtained for CLIA. Based on the results of this study, CLIA can be used as a reference method in detecting Salmonella antibodies in the meat juice of slaughter pigs.     

Establishment of serological herd profiles for zoonoses and production diseases in pigs by “meat juice multi-serology”

The most important pork-borne zoonotic diseases in humans such as Salmonelloses and Yersinioses cause only latent infections in pigs. Thus, the infection of pigs does not result in apparent or palpable alterations in the pig carcasses. This is the major reason, why the traditional meat inspection with adspection, palpation and incision is not able to control the food safety risks of today. The objective of this paper is to evaluate a set of serological tests, which provides a classification of pig herds into “zoonoses risk categories” as demanded by EU law and into “herd health risk categories” by using meat juice as diagnostic specimen for ELISA tests. Serological data that were obtained by testing meat juice samples from various pig herds were analyzed as proof of the “meat juice multi-serology” concept. For that, at least 60 meat juice samples from 49 pig herds each were taken between September 2010 and March 2011 and tested for antibodies against zoonotic pathogens (Salmonella spp., Trichinella spp., Yersinia enterocolitica and Toxoplasma gondii) and against pathogens causing production diseases (Mycoplasma hyopneumoniae, influenza A virus subtype H1N1, influenza A virus subtype H3N2 and PRRSV). Apparent and true animal prevalence, herd prevalence values and intra-herd seroprevalence values as well as the predictive values for the herd and the animal prevalence values were calculated for each pathogen and each of the 49 randomly selected herds. The herd seroprevalence values (one seropositive sample per herd determined a “positive herd”) for Y. enterocolitica, Salmonella spp., T. gondii, M. hyopneumoniae and PRRSV were higher than 80%, respectively, for the influenza A viruses between 60% and 14% and for Trichinella spp. 0%. Although all herds were located in the same area in the Northwest of Germany within a radius of 250 km, the intra-herd seroprevalence values for all tested pathogens, except for Trichinella spp., varied remarkably from herd to herd. In the case of Y. enterocolitica and T. gondii the intra-herd seroprevalence values varied even from zero to 100%. This shows that a serological risk categorization of pig herds regarding zoonoses and production diseases is meaningful if used for risk-based decisions in the framework of the new meat inspection concept and as part of the herd health management system. Thus, the development of a cost-efficient, time- and labour-saving test system for simultaneously detecting various antibodies should be the next step for an extensive implementation of the meat juice multi-serology concept.     

猪血浆蛋白质多态性与肉质性状的关系研究

为筛选猪的肉质性状的生化遗传标记,以湖南省望城种猪场大白猪群为研究对象,采用聚丙烯酰胺凝胶电泳检测了大约克夏猪群4种血浆蛋白质多态性,并利用通用线性模型分析了血浆蛋白质多态性与肉质性状的关系,结果表明:除Amy1的AB型对失水率性状有显著水平的负效应(P<0.05),各蛋白位点不同基因型对5个肉质性状的效应均没有达到显著水平(P>0.05)。     

不同肉质改良剂在肉猪肥育阶段的试验效果

随着国民经济发展和人民生活水平不断提高 ,人们对畜产品质量的要求也越来越高 ,对优质无公害放心肉的需求量越来越大 ,这种趋势将会持续增长。随着我国规模化养猪业的发展 ,在高产、高效的同时 ,如何生产符合国家有关标准和确保消费者健康安全的优质猪肉是养猪者所面临的重要问题。各科研单位开发研制的肉质改良剂 ,正是在国家安全生产猪肉的有关政策法规基础上生产出的高科技产品 ,对发展安全、高效、优质的放心肉和促进养猪业可持续发展都具有重要的现实意义。肉质改良剂具有促进生长、降低料耗、提高肉的持水性和改善肉色、提高饲料利用…     

Analysis of meat juice ELISA results and questionnaire data to investigate farm-level risk factors for Salmonella infection in UK pigs

The study set out to explore risk factors for Salmonella infection in pigs, based on seroprevalence amongst slaughtered pigs, using a large study population of holdings and a comprehensive list of farm characteristics. Farm data were collected from pig quality assurance schemes and supplemented by a postal questionnaire. These data were used with meat juice serology results from ongoing abattoir Salmonella surveillance, for a multivariable risk factor analysis, modelling the ELISA sample to positive ratio directly (ELISA ratio). The study population contained 566 farms, covering a geographically representative spread of farms within the United Kingdom, with a mean average of 224 sample results per holding over a 4-year period. The model highlighted that temporal factors (quarterly and yearly cycles) and monthly meteorological summaries for rainfall, sunshine and temperature were associated with Salmonella presence (P < 0.01). The ELISA ratio was found to be highest in autumn and lowest in spring and summer, whereas yearly averages showed a greater degree of variation than seasonal. Two feed variables (homemix and barley) were found to be protective factors, as was a conventional, rather than organic or freedom foods, farm enterprise type. The number of annual pig deliveries and dead stock collections, and the main cause of pig mortality on the farm were found to be associated with Salmonella infection. Scottish farms had a lower ELISA ratio than other regions, and an increased number of pig farms within a 10-km radius was associated with a higher ELISA ratio. The study demonstrated that the analysis of routinely collected data from surveillance and quality assurance schemes was cost-effective, with sufficient power to detect modest associations between Salmonella and exposure variables. The model results can be used to inform on-farm Salmonella control policies and could target-specific geographical regions and seasons to assist the efficiency of surveillance.     

生长猪日粮中添加虫肽蛋白对肉质和风味的影响

本试验选用保育出栏的杜×长×大三元杂交小猪96头,随机分成两个组,试验组日粮中添加5％虫肽蛋白．对照组饲喂常规日粮（玉米豆粕型）。经过105d的饲喂试验．结果表明：试验组日增重比对照组提高2．24％;饲料转化率比对照组提高0．75％。通过屠宰猪对肉质和风味进行观察和品尝．试验组猪肉比较鲜红、肉味口感爽滑、肥肉肥而不腻、清煮肥肉汤中油腻甚少、肉质细嫩、甘香可口：对照组猪肉色泽暗红、口感有渣、含酸味、有肉膻味。     

Necessity of double testing of meat juice samples from pigs using ELISA for the determination of Salmonella status in pig farms]

According to the test protocol of the "meat juice ELISA" for detection of salmonella antibodies in pigs, all meat juice samples and serum controls are to be tested in duplicate. Results from routine investigations of repeatedly double tested meat juice and serum samples have been used to analyze the effect of double testing versus single testing with regard to the reliability of the final result. In case of an individual animal, testing of samples in duplicate increases the reliability of the results significantly, especially, if samples are retested at different occasions. In contrast, such a difference between mono and double testing of samples is not of importance when a group of animals is tested in order to determine the mean antibody rate in a herd. Here, results from double testing practically do not contribute to a higher reliability of the final result. This observation provides the possibility to reduce the costs for investigation programmes drastically.     

Comparing the results of the serological detection of Salmonella antibodies in blood serum and meat juice from different muscles from slaughter pigs

The German Salmonella Monitoring Programme started by the QS-System in 2002 (Blaha, 2004) is mandatory due to the so-called "Salmonella Regulation for Pigs" since 2007 (Anonym, 2007). The Regulation does not clearly prescribe the specific muscle which is to be taken as source of the meat juice. Thus, at different slaughter plants meat samples are also taken from different muscles and several scientific papers describe various muscles as source of the meat juice, too. The objective of this study was to compare the serological results of meat juices from three different locations (diaphragm pillar, neck, belly muscle) to each other and to those of the blood serum from exactly the same animals. All samples were simultaneously tested for Salmonella antibodies by two serological tests (Salmo-type Pig Screen, LDL, Germany; HerdChek Swine Salmonella, IDEXX, Germany). Comparisons were carried out between the various sample kinds per animal and between the two test systems. The analysis of all results of the meat juices revealed in both test systems a clear decline of the OD% values from the diaphragm pillar to the neck to the belly muscle. The average OD% values of all samples were higher when measured by the HerdChek ELISA (IDEXX, Germany) than by the Salmotype ELISA (LDL, Germany), especially in blood serum. Since the results of the meat juice samples gained from the diaphragm pillar were in both test systems by far the closest to the results of the corresponding serum blood samples, it is recommended to amend the "Salmonella Regulation for Pigs" by prescribing meat from the diaphragm pillar as the only muscle for gaining meat juice.     

Development and Bayesian evaluation of an ELISA to detect specific antibodies to Sarcoptes scabiei var suis in the meat juice of pigs

Samples of ear scrapings, serum and diaphragmatic muscle were collected from 271 fattening pigs at the slaughterhouse. The scrapings were examined for the presence of mites, and tests for specific antibodies to Sarcoptes scabiei var suis in the serum and meat juice were made with an experimental ELISA. The cut-off value for the meat-juice ELISA was estimated at an optical density of 0.5 by receiver operating characteristic curve analysis, on the basis of the cut-off value for the serum ELISA of 0.4. The results of the three tests were used in a Bayesian model to estimate the characteristics of each test. The specificity of the tests of the ear scrapings was considered to be 1 and their sensitivity was estimated by Bayesian analysis to be 0.86, with a 95 per cent confidence interval (CI) of 0.73 to 0.99. The sensitivity of the meat juice ELISA (0.71, 95 per cent CI 0.6 to 0.8) and its specificity (0.77, 95 per cent CI 0.66 to 0.89) were comparable with the sensitivity (0.73, 95 per cent CI 0.6 to 0.8) and specificity (0.81, 95 per cent CI 0.69 to 0.95) of the serum ELISA.     

C-reactive protein in dogs

Serum concentrations of C-reactive protein (CRP) in dogs with various diseases or undergoing various procedures were measured by specific immunoassay. In 20 healthy dogs from various sources, values were all less than 5 mg/L, but in 22 healthy dogs from a single source, values ranged from less than 5 mg/L in 14 dogs and from 8 to 67 mg/L in 8 dogs. Increased concentrations of serum CRP were attained 24 hours after injection of casein (n = 9; median 188 mg/L), ovariohysterectomy (n = 11; median, 144 mg/L), or elective, nonacute orthopedic surgery (n = 10; median, 83 mg/L). After inoculation of Leptospira interrogans serovar canicola (n = 5), the behavior of serum CRP as an acute-phase reactant provided a sensitive and precise objective reflection of in vivo response. The CRP concentration in random single-serum samples from 73 dogs with other inflammatory and noninflammatory disorders ranged from normal (less than 5 mg/L) to 246 mg/L and generally correlated with the extent and activity of disease.     

Toxoplasma gondii in Switzerland: a serosurvey based on meat juice analysis of slaughtered pigs, wild boar, sheep and cattle

Toxoplasmosis is one of the most important zoonotic diseases worldwide and is caused by the protozoan Toxoplasma gondii. Besides vertical infection during pregnancy, humans can get infected post-natally either by peroral uptake of sporulated Toxoplasma oocysts or by ingestion of tissue cysts upon consumption of raw or undercooked meat. The aim of this study was to approximate the risk of human infection via meat consumption by estimating the seroprevalence of T. gondii in slaughtered animals in Switzerland and to compare data with prevalences assessed 10 years ago. The study included pigs, cattle, sheep and wild boar of different age groups and housing conditions whenever possible and applicable. A P-30-ELISA was used to detect T. gondii-specific antibodies and to determine seroprevalences in meat juice of slaughtered animals. A total of 270 domestic pigs (120 adults, 50 finishing, 100 free-ranging animals), 150 wild boars, 250 sheep (150 adults, 100 lambs) and 406 cattle (47 calves, 129 heifers, 100 bulls, 130 adult cows) were tested. Seropositivity increased with the age of the assessed animals. Independent of the age-group, the overall seroprevalence was lowest in wild boars (6.7%), followed by pigs (23.3%), cattle (45.6%) and sheep (61.6%), respectively. Conventional fattening pigs and free-ranging pigs surprisingly had comparable seroprevalences (14.0% and 13.0%, respectively). Unlike in other European countries, where generally a decrease in the number of seropositive animals had been observed, we found that the prevalence of seropositive animals, when compared with that of 10 years ago, had increased for most species/age groups. Conclusively, the results demonstrated a high seroprevalence of T. gondii in animals slaughtered for meat production and revealed that increasing age of the animals is a more important risk factor than housing conditions in Switzerland.     

发酵蛋白饲料对生长育肥猪生产性能和猪肉品质的影响

本试验探讨了在日粮中使用发酵蛋白原料替代普通蛋白原料对生长育肥猪生产性能和猪肉品质的影响。结果表明,以发酵豆粕、发酵棉粕为主要蛋白原料的育肥猪无抗饲料配方产品与常规饲料相比,能显著提高育肥猪末重及平均日增重;能使每头猪养殖增收78.72元,提高毛利33.98%;能显著降低猪肉剪切力和滴水损失,提高猪肉氨基酸水平,改善了肉品质,提高了猪肉营养。     

Evaluation of three commercial enzyme-linked immunosorbent assays for the detection of antibodies against Salmonella spp. in meat juice from finishing pigs in Spain

The control of animal salmonellosis is considered as a major objective in Europe and indirect ELISAs will be important tools for the implementation of control programs for this infection in pigs. We analyse the results yielded by three commercial ELISAs (Herdcheck Swine Salmonella, SALMOTYPE Pig Screen, and PrioCHECK Salmonella) on meat juice samples from a population of slaughter pigs of Aragon, NW Spain, to assess their efficacy using traditional and latent-class approaches. Overall, the Herdcheck Swine Salmonella detected more Salmonella-infected pigs than the other two tests, but its relative sensitivity was low (65.9%). A similar result was observed when only serotypes detectable by this test were considered (69.1%). When a Bayesian approach was used the Herdcheck Swine Salmonella showed also the highest overall accuracy (sensitivity = 88% and specificity = 74%). Our results suggest that a relatively small proportion of the observed prevalence in herds would be explained by using these ELISAs. Also, this study points out that when different ELISA tests are used within the same herd, results may differ substantially. Thus, caution is advised if it is decided to use these assays for herd health classification in Spanish Salmonella control programs.     

Economic values for meat quality traits in pigs.

The aim for this study was to derive economic values for meat quality traits. Meat quality experts from 10 slaughter and retail companies in Switzerland were asked to give an interview in which they indicated their willingness to pay different prices for carcasses from different quality classes. Economic values for the seven meat quality traits color (L*), drip loss, intramuscular fat content, iodine value, pH1 (45 min after slaughtering), pH2 (24 to 30 h after slaughtering), and proportion of premium cuts were derived from the answers. For each trait, a weighted mean of these economic values was calculated using the number of pigs slaughtered by a company per year as a weighting factor. Population mean and standard deviation of the investigated traits were taken from station test results of Swiss Large White pigs (intramuscular fat content, iodine value, pH1, pH2, and proportion of premium cuts) and from the literature (color and drip loss). Weighted means (range among companies) of economic values per slaughter pig on the basis of one phenotypic standard deviation of the trait in Swiss Francs (SFr.) were -22.92 (0 to -62.46) for color, -10.27 (0 to -43.64) for drip loss, 10.84 (0 to 29.43) for intramuscular fat content, -29.90 (-15.54 to -43.58) for iodine value, 11.50 (.67 to 19.79) for pH1, 0 (0) for pH2, and 10.92 (-2.30 to 33.67) for proportion of premium cuts.