Serum Fractions Inhibitory to the Growth of Leptospires

It is known that the growth inhibitory substance of animal sera on Leptospires exists in the albumin fraction. Since the globulin fraction obtained from animal sera having growth inhibitory property may support, though variable individually, some degree of leptospiral growth, it may be added, with 5% of pooled rabbit serum, to the medium to be used for the propagation of Leptospires.     

A Study of Complement-fixation and Serum Agglutination Tests on Vibrio fetus Infected and Immunized Cattle

Complement-fixation (CF) and tube agglutination (TA) tests for demonstration of Vibrio fetus antibodies were conducted on the sera of three groups of ten heifers. One group was vaccinated subcutaneously with a commercial V. fetus var venerealis bacterin and challenged intra-utero, at the external os cervicus one month later; the second was infected only and the third vaccinated only.

The vaccinated cattle developed high CF serum titers, but no such increase was observed in animals infected only. A moderate increase in serum antibody titers was demonstrated by the TA test following either infection or vaccination; although titers observed were not higher than those observed in the sera of some apparently normal uninfected animals. The group receiving both vaccine and challenge was the only one in which significant serum antibody titers were demonstrable by the TA test. The sera of these animals also had significant titers in the CF tests.

The CF and TA tests detected serum antibodies produced by the parenteral inoculation of V. fetus antigen. These two tests were of limited value in detecting serum antibodies from animals with genital V. fetus var venerealis infection, although the formation of local antibodies was demonstrable by the vaginal mucus agglutination test.

     

Enzootic Pneumonia of Pigs: Complement-Fixation Tests for the Detection of Mycoplasma Antibodies in the Serum of Immunized Rabbits and Infected Swine

The direct, the modified direct and the indirect complement-fixation tests were investigated as methods for the detection of antibodies for the enzootic pneumonia mycoplasma and for Mycoplasma hyorhinis in the serum of infected pigs and of immunized rabbits.

Only the modified direct complement-fixation test in which the guinea-pig complement is supplemented with fresh, normal unheated calf serum was suitable for the detection of mycoplasma antibodies in sera of infected swine. Based on the close correlation between the production of typical lung lesions in experimentally infected pigs and the appearance of significant serum antibody titres, the modified direct complement-fixation test provides for the first time a sensitive, specific in vitro method for the detection of enzootic pneumonia in the live pig. This test also permitted the in vitro differentiation of the mycoplasma causing enzootic pneumonia from M. hyorhinis which causes polyserositis.

Antibodies in the sera of rabbits were demonstrable by the ordinary direct complement-fixation test. However, in contast to the observation made with swine sera, only a slight quantitative antigenic difference between the enzootic pneumonia mycoplasma and M. hyorhinis was seen when the tests were performed with rabbit serum antibodiies.

     

Prevalence and Species Distribution of Yeast in Mammary Glands of Dairy Cows in Minnesota

A study of the prevalence of yeast-like fungi in the mammary glands of dairy cattle was conducted in Minnesota. Quarter samples from 6,020 cows were cultured for yeast. Growth of organisms was obtained from 3.2% of the quarter milk samples. The rate of yeast infection for Minnesota dairy cattle in this study was 2.0%.

The majority of the yeast isolated belonged to one of four species of the Candida genus. Candida krusei, Candida parakrusei, Candida guilliermundi, and Candida tropicalis, comprised 89% of the yeasts isolated. All of these species have been reported to cause clinical mastitis (1, 7, 9, 10, 12, 13, 15, 16).

It would appear that yeast-like fungi are of sufficient prevalence in mammary glands that yeast infection would be considered in the differential diagnosis in cases of clinical mastitis.

     

Evaluation of an enzyme-linked immunosorbent assay (ELISA) for serodiagnosis of infectious bovine rhinotracheitis infection, with results of a preliminary survey

An indirect enzyme linked immunosorbent assay (ELISA) procedure was evaluated against the serum neutralisation test (SNT) for the detection of antibodies to infectious bovine rhinotracheitis virus (bovine herpesvirus type l), using 2028 sera from 166 dairy and 172 beef cattle herds. The results showed the ELISA to give high levels of agreement with the SNT in classifying positive and negative sera (98% and 97% respectively). Such disagreements as did occur involved weakly reactive sera with SNT titres of % or less. A number of sera (n=123) with trace neutralising activity of doubtful diagnostic significance were found to give marginal reactivity with ELISA. ELISA absorbance values were found to be highly correlated with SNT titres (r=0.909) on an overall basis, though agreements were lower with individual sera. The ELISA procedure was quicker, cheaper, and detected more reactors than the SNT. It also allowed results to be obtained with a number of sera which were unsuitable for testing by SNT because of their cytotoxic nature. Analysis of ELISA results showed reactors to be present in 57% of tested sera, representing 81% of cattle herds. Reactor rates for sera and herds in the South Island, (37% and 58%), were significantly lower than for those in the North Island (64% and 88%). Antibody prevalence was also found to be significantly lower in districts having a low annual rainfall (<850 mm), and to be lower in beef cattle than in dairy cattle. A surprising exception to the latter occurred in low rainfall districts, where dairy cattle showed significantly lower reactor rates than local beef animals.     

Prevalence of antibodies to toxoplasma gondii in cattle and swine in the Netherlands: Towards an integrated control of livestock production

Summary

Serological surveys of the prevalence of antibodies against Toxoplasma gondii were carried out amongst swine and cattle in the Netherlands. Data were analysed according to the different categories of animals. The results show very low seroprevalences of Toxoplasma gondii in finishing pigs (1.8%) and in fattening calves (1.2%). In sows and dairy cattle, respectively, seroprevalences of 30.9% and 27.9% respectively, were found, demonstrating clearly the environmental infection pressure and illustrating the importance of housing and management in establishing low infection rates.

Substantially different seroprevalences were found between dairy cattle sampled in the North and in the South of the Netherlands (13.1% and 42.6%, respectively).

The infection rates in the samples from finishing pigs, fattening calves, and dairy cattle demonstrate that seroprevalences in individual farms or herds may differ considerably. Investigation of the factors involved can be useful in determining the causes of infection and for developing measures with regard to prevention. The very low seroprevalences in finishing pigs and fattening calves indicate, however, that the production of toxoplasma‐free meat may be well within reach in modern husbandry.

Since farm animals easily are infected, serological screening of individual farms or herds for the absence of T. gondii infection, as a part of the Integrated Quality Control programme, can be helpful in determining the quality of livestock production and in developing certain standards of hygiene for individual farms.     

Absence of a weight gain response to Vitamin B12 supplementation in weaned dairy heifers grazing pastures of marginal cobalt content

Aim. To obtain information on serum and liver vitamin B₁₂ and urinary methylmalonic acid concentrations as diagnostic tests to predict a weight gain response to supplementation with vitamin B₁₂ in young dairy cattle when grazing pasture of low cobalt content.

Methodology. Forty dairy cattle (12 Friesian, 14 Friesian × Jersey and 14 Jersey) were allocated to two equal sized groups, treated and untreated, based on liveweight. At monthly intervals for 14 months, all animals were weighed, their serum and urine sampled, their liver biopsied and the pasture sampled from the paddocks they were grazing and going to graze. Serum and liver were assayed for Vitamin B₁₂ concentrations. For the first 5 months of the trial, urine was assayed for methylmalonic acid concentrations. Both washed and unwashed pasture samples were assayed for cobalt concentrations.

Results. No weight gain response occurred to Vitamin B₁₂ supplementation in young growing cattle grazing pasture with a cobalt concentration of 0.04-0.06 mg/kg DM. For 5 months of the trial, liver Vitamin B₁₂ concentrations from untreated calves were in the range 75-220 nmol/kg and serum vitamin B₁₂ concentrations were as low as 72 pmol/1. There was no associated growth response to supplementation.

Conclusion. Further trials involving young cattle grazing pastures with cobalt concentrations less than 0.04 mg/kg DM are required to reliably determine liver and serum Vitamin B₁₂ concentrations at which growth responses to Vitamin B₁₂ or cobalt supplementation are likely under New Zealand pastoral grazing conditions.     

The Dutch Brucella abortus monitoring programme for cattle: the impact of false-positive serological reactions and comparison of serological tests

The Dutch national Brucella abortus eradication programme for cattle started in 1959. Sporadic cases occurred yearly until 1995; the last infected herd was culled in 1996. In August 1999 the Netherlands was declared officially free of bovine brucellosis by the European Union. Before 1999, the programme to monitor the official Brucella-free status of bovine herds was primarily based on periodical testing of dairy herds with the milk ring test (MRT) and serological testing of all animals older than 1 year of age from non-dairy herds, using the micro-agglutination test (MAT) as screening test. In addition, serum samples of cattle that aborted were tested with the MAT. The high number of false positive reactions in both tests and the serum agglutination test (SAT) and complement fixation test (CFT) used for confirmation seemed to result in unnecessary blockade of herds, subsequent testing and slaughter of animals. For this reason, a validation study was performed in which three indirect enzyme-linked immunosorbent assays (ELISAs), the CFT and the SAT were compared using a panel of sera from brucellosis-free cattle, sera from experimentally infected cattle, and sera from cattle experimentally infected with bacteria which are known to induce cross-reactive antibodies (Pasteurella, Salmonella, Yersinia, and Escherichia). Moreover, four ELISAs and the MRT were compared using a panel of 1000 bulk milk samples from Brucella-free herds and 12 milk samples from Brucella abortus- infected cattle. It is concluded that the ELISA obtained from ID-Lelystad is the most suitable test to monitor the brucelosis free status of herds because it gives rise to fewer false-positive reactions than the SAT.     

Electrophoretic Studies of Sera from Cattle Vaccinated or Naturally Infected with Brucella Abortus

Examinations of the electrophoretic behaviour in cellulose acetate were made on the proteins of sera from 18 field cases of brucellosis, 15 calves recently vaccinated with strain 19 Brucella abortus and from 28 normal cattle. The total protein and γ-globulin content of the sera of the naturally infected, serologically positive cattle tended to be somewhat higher than that of sera from most normal cattle. A few of the serologically-negative normals also had defenitely elevated serum γ-globulin values. In the vaccinated calves there was an increase both in total serum protein and γ-globulin but its magnitude in different individuals was not directly related to the rise in their antibody titre.     

Bovine Infectious Keratoconjunctivitis: Serological Aspects of Moraxella bovis Infection

A modification of a gel diffusion precipitin test (GDPT) was used to detect antibodies for Moraxella bovis (M. bovis) in the sera of cattle affected with bovine infectious keratoconjunctivitis (BIK). The test was also used for the detection of sequential antibody development in cattle vaccinated with cultures of M. bovis. Also, strains of M. bovis isolated from cattle herds affected with BIK were characterized serologically as a part of an identification scheme using the test.

A comparison of the antigenic properties of various strains of M. bovis and M. bovis-like organisms was conducted using the test. The results indicated that there might be antigenic relationships between M. bovisand M. bovis-like organisms such as Moraxella liquefaciens, Moraxella nonliquefaciens, an unidentified hemolytic diplococcus, Mima polymorpha, Mima polymorpha var. oxidans and Herellea vaginicola

The authors suggest that the GDPT can be used for serological studies of BIK, and the identification and antigenic analysis of M. bovis. They indicate, however, that a more definitive study is needed to evaluate the reliability of the test for quantitative work.

     

Serological detection of multiple retroviral infections in cattle: bovine leukemia virus, bovine syncytial virus and bovine visna virus

Individual experimental animals used in our studies on bovine leukemia virus (BLV) are routinely screened for the presence of antibodies to the three bovine lymphotropic retroviruses. We utilized these screening methods to examine frozen sera from eight herds for antibodies to BLV, bovine visna virus (BVV) and bovine syncytial virus (BSV). Serum samples from 235 animals in four dairy and four beef herds were analyzed. Detection methods used included indirect fluorescent antibody tests of virus-infected cell cultures (BLV, BSV, BVV) and agar gel immunodiffusion (BLV). Sera from the BLV-infected animals in the dairy herds showed the highest single (50%, 49/97) and multiple (30%, 29/97) infections compared with 5% (7/138) and less than 1% (1/138), respectively in the beef herds. Single BVV infections were not detected in the dairy herds, but 11% (11/97) of the sera contained antibodies to BVV plus BLV or BSV. Five sera from beef cattle had antibodies only to BVV and four were obtained from one herd. Only one beef serum of the 138 tested demonstrated multiple antibodies (BLV, BVV).     

The Effects of Age and Previous Infection on the Development of Gastrointestinal Parasitism in Cattle

An age resistance in cattle to establishment of infection with Cooperia oncophora was not demonstrated. Cattle exposed to a heavy infection for the first time at approximately 15 months of age were as susceptible to establishment of infection as 3 to 4 month old calves, but stunting of worms and inhibition of ovulation did occur in the older animals, possibly due to a rapid development of resistance as a result of sensitization by a previous extremely light infection.

An age resistance in cattle to infection with Nematordirus helvetianus was not clearly demonstrated. At necropsy, 8 of 9 calves and 2 of 6 yearlings exposed to pasture infections for the first time did harbour Nematodirus worm burdens, while yearlings which were heavily infected previously were completely free of this species.

Under the conditions of this investigation, age and acquired resistance to Ostertagia ostertagi were not demonstrated, since previously non-exposed calves and yearlings and previously infected yearlings had comparable worm burdens.

This study demonstrated the adverse effect that heavy parasitism has on the development of susceptible animals. Animals which had little or no exposure to parasitism were found to be much more susceptible to the effects of parasites than were resistant animals.

     

Evaluation of enzyme-linked immunosorbent assay using milk samples as a potential screening test of bovine tuberculosis of dairy cows in Korea

An enzyme-linked immunosorbent assay (ELISA) using bulk tank milk samples was evaluated as a screening test for bovine tuberculosis (TB), a contagious chronic disease of cattle. An ELISA with MPB70, a major antigen of Mycobacterium bovis was performed using paired sets of milk and sera samples from 33 tuberculin-positive and 43 tuberculin-negative cattle. Anti-MPB70 antibodies were detected in milk samples and there was a significant correlation between seroreactivities of milk and sera samples (R² = 0.83). Using the tuberculin skin test as the reference test, the sensitivities of ELISA using milk and sera samples were 87.8% and 81.8%, respectively, and the specificities were 97.7% and 100%, respectively.In the screening test using bulk tank milk samples from 931 dairy herds in Whasung, Gyeonggi-do, Korea, the positive rate for anti-MPB70 antibody was 4.5% (42/931) and the tuberculin-positive rate was 2.8% (26/931). Individual milk samples (n = 253) were collected from randomly selected 8 problematic and 3 negative herds (positive and negative in the screening test by MPB70 ELISA using bulk tank milk samples, respectively) and tested by MPB70 milk ELISA. In the problematic herds, positive rates were 10.5% (20/190) for anti-MPB70 antibodies in milk ELISA and 2.1% (4/190) in the tuberculin skin test. More than one dairy cows were positive by milk ELISA among the problematic herds, and all tuberculin-positive dairy cows were positive in the milk ELISA. Further, no positive cows were detected in negative herds both by milk ELISA and tuberculin skin test. These results suggest that an ELISA, using bulk tank milk samples, might be a potential efficient screening test for bovine TB of dairy cows.     

Evaluation of ELISA in the serodiagnosis of bovine farcy

Mycobacterium farcinogenes is the causal agent of bovine farcy, a chronic infectious disease of zebu cattle in some parts of tropical Africa. Whole cell homologous antigen of M. farcinogenes was used in the standardization and evaluation of an enzyme linked immunosorbent assay (ELISA) for the detection of circulating antibodies against bovine farcy using sera from confirmed bovine farcy and from bovine farcy-free cattle. The cut-off optical density (OD) value was decided at 1.8 using filter 405nm after one hour of incubation at 37°C. Accordingly, 115 out of 124 (92.7%) serum samples from clinically proven bovine farcy cattle were reported sero-positive. Sera from cattle infected with M. avium and M. paratuberculosis revealed OD value <1.8, indicating the differential diagnostic ability of M. farcinogenes antigen. Our test sensitivity was 92.7% and specificity was 97%, therefore could be routinely employed to support early clinical diagnosis, epidemiological surveys and for screening animals before exportation to farcy-free regions.     

Comparative Study of Agar Mediums for Propagation of Ruminant Mycoplasma

A brain heart infusion agar supplemented with 16.7% rabbit serum (BHIR) was found the most suitable for the culturing of ruminant mycoplasma. Gourlay medium and Perreau medium (4, 5) were not suitable for growth of Mycoplasma mycoides var. mycoides or M. agalactiae, but were satisfactory for M. mycoides var. capri.

Four strains of M. mycoides var. mycoides, three strains of M. agalactiae and three strains of M. mycoides var. capri were grown in our laboratory.

     

Seroprevalence and associated risk factors of bovine brucellosis in Addis Ababa dairy farms

A cross-sectional study was carried out on bovine brucellosis in Addis Ababa dairy farms from November 2003 to April 2004. A total of 1,202 blood samples were collected from non-vaccinated, cross-bred dairy cattle. The Rose Bengal plate test (RBPT) was used as a screening test. Those serum samples reacting positively to RBPT were subjected to the complement fixation test (CFT) for confirmation. The RBPT detected 30 of 1,202 (2.5%) of the samples as brucellosis positive. The positive sera when further retested using CFT, 18 out of the 30 RBPT positive sera were confirmed to be positive. The prevalence of brucellosis based on CFT in the study area was 1.5%, and all positive sera were from female cattle. Result of the questionnaire survey revealed that percentage of 4.4% abortion and 9.5% retained fetal membranes. Abortion and retained fetal membranes were associated with Brucella antibodies (P?相似文献   

Observations on Trypanosoma theileri Infection in Cattle

Naturally occurring Trypanosoma theileri infection was studied in two cattle herds. Herd A was a dairy herd of approximately 250. Herd B was an isolated herd of 32 and contained both dairy and beef breeds. Blood samples were collected from all animals in Herd A during July and August on two successive years. Samples were collected from Herd B at monthly intervals. Total leukocyte and differential counts packed cell volume determinations, and trypanosome cultures were made on each sample.

Infection was detected in all age groups between seven months and fifteen years but it was rare in calves. Infected animals were not consistently positive for trypanosomes on consecutive blood cultures and there was considerable variation between infected individuals. Positive cultures were usually obtained from some animals while others were positive intermittently. No correlation was found between trypanosome isolations and the season of the year.

A correlation was found between trypanosome isolation and lymphocytosis. Of the 920 blood samples examined, approximately one in every five trypanosome positive samples had lymphocyte levels in the Bendixen positive range. Approximately one in every twenty trypanosome negative samples had lymphocyte numbers in the Bendixen positive range. Evidence indicated that trypanosome isolation from animals with lymphocytosis was not caused by increased numbers of infected buffy coat cells in the inoculum cultured.

Eight calves were inoculated intravenously with trypanosome-infected blood. Lymphocyte numbers increased an average of 3549 per cumm above pre-inoculation levels in seven and remained essentially unchanged in one. Prior to inoculation with infective blood, two of the calves were intravenously inoculated with trypanosome-infected blood that had been frozen and thawed to kill the trypanosomes contained in it. Neither developed lymphocytosis following this inoculation.

No clinical disease problems which could be attributed to trypanosome infection were found.

     

Epizootiologic Studies of Shipping Fever of Cattle: I. The Microbial Agents Isolated

Nineteen strains of Pasteurella spp., but no viruses cytopathogenic for bovine embryonic kidney cells were isolated from pneumonic lesions present in “normal” veal calves at slaughter.

In studies on two herds of native cattle and six lots of western feeder calves, Pasteurella spp. were isolated from nasal swabs from healthy cattle and those with shipping fever. Viruses of the psittacosis-lymphogranuloma group were isolated from nasal swabs from animals in five groups. Viruses provisionally identified as bovine enteroviruses were isolated from nasal swabs of calves in two lots.

There was serologic evidence of a temporal association of myxovirus para-influenza 3 (PI3) with shipping fever in three lots of calves. From two of these three lots, strains of PI3 were isolated from ten animals, four of which had clinical shipping fever at the time of virus isolation.

     

Pasteurella haemolytica of Cattle: Serotype, Production of Bete-galactosidase and Antibacterial Sensitivity

Two hundred and three isolates of Pasteurella haemolytica from cattle were studied. They originated from the nasal cavity of cattle in housed herds; the nasal cavity and pneumonic lungs of experimental feedlot calves and from pneumonic bovine lungs submitted for bacteriological diagnosis.

To determine whether a single characteristic or combination of characteristics might be a feature of isolates collected from animals with pneumonic pasteurellosis (Shipping Fever), the following tests were made. Cultures were serotyped by indirect haemagglutination; the ability to produce beta-galactosidase was examined in the ortho-nitrophenyl-beta-D-galactopyranoside (ONPG) test and antibacterial sensitivity tests were done. None of these factors could be directly related to the role of P. haemolytica in “Shipping Fever”.

     

Seroprevalence survey for Anaplasma card-test reactors in Louisiana,U.S.A., cattle

During 1982–1984 a total of 274 herds, or 11 175 cattle, throughout the State of Louisiana in south central U.S.A. were bled and their serum stored in a serum bank at −40°C; nine of these herds were bled twice. Using the rapid-card agglutination test these sera were tested for Anaplasma antibodies and the overall seroprevalence was 5.64% of the beef cattle seropositive and 4.27% of the dairy cattle.