Correlations among the somatic cell count of individual bulk milk, result of the California Mastitis Test and bacteriological status of the udder in dairy cows

In a survey of about 3000 dairy cows producing low somatic cell count (SCC) milk and kept on a large-scale dairy farm, California Mastitis Test (CMT) positivity was found in 2714 udder quarters of 1491 cows. Pathogenic microorganisms were isolated from 57.6% of these 2714 udder quarters during bacteriological examination. The commonest pathogens were coagulase-negative staphylococci (CNS, 41%) and Staphylococcus aureus (32.5%); however, udder infections caused by environmental streptococci (12.8%) and coliform bacteria (6.8%) were also common. All pathogens resulted in a significant increase of the SCC in individual bulk milk (IBM) samples. In the case of CNS, this SCC elevation in IBM was significantly lower than in the case of infection by the other pathogens. In spite of this, because of the high number of udder infections caused by CNS, the adverse effect exerted by CNS on dairy herds is considered to be substantial. It was found that 54.6% of all CMT-positive cows produced IBM of an SCC below 400 thousand per ml. The milk produced by 41% of the 315 cows excreting S. aureus also had an SCC below 400 thousand per ml. This poses a serious risk of infection to the healthy herdmates. At the same time, 11% of the infected cows produced IBM with an SCC below 100 thousand per ml. On the basis of these findings, only the regular analysis of SCC of IBM can be a reliable indicator of chronic intramammary infection. As the SCC of milk produced by CMT-positive cows (and especially of those excreting pathogens) tended to increase with advancing lactation, the authors suggest that an efficient drying-off therapy should be used to restore udder health and, whenever justified, culling of cows cannot be avoided either.     

Herd-level seroprevalence and risk-mapping of bovine hypodermosis in Belgian cattle herds

Our objective was to determine the seroprevalence of Hypoderma spp. and to develop a spatial model describing the risk surface of warble-fly infection in Belgian cattle herds (adjusting for herd size, herd type, local temperature, rainfall, relative air humidity and land-cover). This survey was carried out in 390 selected herds of all types (dairy, mixed and beef) from December 1997 to March 1998, which were included in a national infectious bovine rhinotracheitis and paratuberculosis (Johne's-disease) survey. All animals >24 months old were blood sampled and an ELISA was used on pooled serum samples (10 animals per pool). The herd seroprevalence was 48.7% (95% confidence interval: 43.6-53.8); positive herds were mainly in the south of the country and along the North Sea coast. The logistic multiple-regression model of herd-level seropositivity indicated that mixed-type and beef-cattle herds have more than four-fold and two-fold increases in the odds of being Hypoderma-positive, respectively, compared with dairy herds.     

Regional eradication of Mycoplasma hyopneumoniae from pig herds and documentation of freedom of the disease

The objectives of this study were to 1) screen all sow herds in a region for M. hyopneumoniae, 2) to effectuate an eradication programme in all those herds which were shown to be infected with M. hyopneumoniae, and 3) to follow the success of the screening and the eradication programmes. The ultimate goal was to eradicate M. hyopneumoniae from all member herds of a cooperative slaughterhouse (153 farrowing herds + 85 farrowing-to-finishing herds + 150 specialised finishing herds) before year 2000. During 1998 and 1999, a total of 5067 colostral whey and 755 serum samples (mean, 25 samples/herd) were collected from sow herds and analysed for antibodies to M. hyopneumoniae by ELISA. Antibodies were detected in 208 (3.6%) samples. Two farrowing herds (1.3%) and 20 farrowing-to-finishing herds (23.5%) were shown to be infected with M. hyopneumoniae. A programme to eradicate the infection from these herds was undertaken. During March 2000, a survey was made to prove the success of the screening and the eradication programmes. In total, 509 serum samples were collected randomly from slaughtered finishing pigs. Antibodies to M. hyopneumoniae were not detected in 506 of the samples, whereas 3 samples were considered suspicious or positive. Accordingly, 3 herds were shown to be infected. One of the herds was previously falsely classified as non-infected. Two of the herds were finishing herds practising continuous flow system (CF). Unlike finishing herds which practice all-in/all-out management routines on herd level, CF herds do not get rid of transmissible diseases spontaneously between batches, for which reason a screening was made in the rest of the CF herds (total n = 7). Consequently, 2 more infected herds were detected. In addition to the results of the survey, a decreasing prevalence of lung lesions at slaughter (from 5.2% to 0.1%) and lack of clinical breakdowns indicated that all member herds were finally free from M. hyopneumoniae in the end of year 2000.     

Survey of gastrointestinal nematode parasites in Saskatchewan beef herds

A survey of gastrointestinal parasites in Saskatchewan beef herds was conducted over the summer of 2014. Fecal samples were collected on 3 occasions during the summer grazing season from beef cows and calves from 14 herds. The mean number of strongylid eggs per gram of feces recovered from calves increased 9-fold (95% CI: 4.5 to 18) over the summer period, while egg counts in the cows remained constant over the same period. The prevalence and infection intensities of gastrointestinal nematode parasites in cow-calf herds in Saskatchewan were comparable to what is seen in cattle grazing in the northern regions of the United States and for which anthelmintic treatments have resulted in positive production benefits.     

Observations of leptospirosis in farmed deer

AIMS: Slaughterhouse and on-farm surveys were undertaken to investigate some aspects of leptospirosis (Leptospira interrogans) in farmed deer in the lower North Island of New Zealand. METHODS: Blood samples and kidneys were collected at slaughter from 601 l-year and older red and red X Wapiti stags and 21 adult hinds from 53 farms (10 or 12 deer per farm). Serum samples were analysed for up to seven Leptospiral serovars. Gross and histological examinations of kidneys were undertaken. Kidneys from 202 deer were cultured for leptospires. A follow-up postal questionnaire (68% response) indicated one herd had been vaccinated prior to the survey. Serological analyses were also carried out on serum bank samples from a previous on-farm survey involving male and female weaner, yearling and adult red deer from 16 commercial deer farms in March and November. RESULTS: Serological reactions at titres > or = 96 to serovar hardjo were present in 73.6%, pomona in 41.5%, copenhageni in 11.3% and tarassovi in 15.1% of farms from the slaughterhouse survey. Antibodies to serovars australis, ballam and balanica were present in three, one and four of six herds studied, respectively. Titre prevalence to hardjo was higher than that of pomona and other serovars within farms. Cultures for Leptospira were positive in 10 stags from six lines with similar prevalence across age groups. Histological examination showed many gross lesions were associated with mild interstitial cellular infiltration characteristic of subclinical Leptospiral infections. Some sections from culture-positive kidneys contained spirochetes in renal tubules. The on-farm survey showed a 10-30% within-herd prevalence of pomona and hardjo titres in 56% of 3-month-old deer herds, but by 11 months of age, 100% of herds were titre-positive with high prevalences to one or both serovars. Concurrently, herds of 1-year-old and adult deer on the same farms were all seropositive. CONCLUSION: This study has shown that Leptospiral infections are common in farmed deer in the survey area.     

Monitoring antibodies to Mycoplasma hyopneumoniae in sow colostrum--a tool to document freedom of infection

In a survey in Finland in 1995, 14,919 colostral whey samples from 530 farrowing herds were analysed by a monoclonal blocking-ELISA to detect antibodies to Mycoplasma hyopneumoniae (M. hyopneumoniae). Antibodies were detected in 274 (1.8%) samples and in 42 herds (7.9%). The median prevalence of sows with antibodies in seropositive herds was 28.2% (range, 2.7-100%). According to clinical and pathological follow-up in finishing herds in 1996, all of the farrowing herds which were seronegative in 1995, were truly non-infected with M. hyopneumoniae. In acutely infected herds, samples collected earlier than 2 h after farrowing were 3 times more likely to contain antibodies than samples collected 2-12 h after farrowing (odds ratio, 3.0; 95% CI, 1.4-6.6). Repeated freezing or spoilage of the colostrum samples did not cause biologically relevant problems for the ELISA. Antibodies to M. hyopneumoniae were shown to persist up to 3 years in some sows. As a conclusion, colostrum samples were very sensitive samples for the screening of herds for M. hyopneumoniae infection and possibly also for a regular surveillance.     

Increasing prevalence of Coxiella burnetii seropositive Danish dairy cattle herds

A study based on bulk tank milk samples from 120 randomly selected dairy cattle herds was conducted to estimate the prevalence of Coxiella burnetii seropositive dairy herds, to describe the geographical distribution, and to identify risk factors. Using the CHEKIT Q-fever Antibody ELISA Test Kit (IDEXX), the study revealed a prevalence of 79.2% seropositive herds, 18.3% seronegative herds, and 2.5% serointermediate herds based on the instructions provided by the manufacturer. Multifactorial logistic regression showed statistically significant associations (P < 0.01) between C. burnetii seropositivity and increasing herd size (OR = 1.02 per cow increment) and increasing regional average number of cattle per dairy herd (OR = 1.02 per animal increment). Herds >150 cows had 17.9 times higher odds of testing positive compared to herds <80 cows. The regional average number of cattle herds per square kilometer was borderline significantly related to the occurrence of seropositive dairy herds (P = 0.06). The results indicate an increased prevalence of seropositive dairy herds since the previous survey in 2008 and an adverse impact of increasing herd size and cattle density on the risk of seropositivity.     

A survey of Theileria sergenti infection, daily weight gain and conception proportions in 85 herds of grazing heifers in Japan

A survey of Theileria sergenti infections, daily weight gain and conception proportion was conducted in 85 herds of grazing heifers in Japan. Basic information and epidemiological data from participating herds were obtained by mailed questionnaires, which were completed by field veterinarians. The average cumulative incidence and proportion of treated animals in the participating herds were 25.7 and 21.1%, respectively. The average daily weight gain and conception proportion were 0.51 kg per day and 56.9%, respectively. The basic information and epidemiological data had a large range and standard deviation, which reflect the wide diversity of the grazing herds in Japan. Herds with heavy tick infestation had significantly higher cumulative incidence and proportion of treated animals, therefore, this factor can be a good estimator to predict the occurrence and loss by theileriosis of the herds. The present questionnaire survey was useful for obtaining information about herds in different regions, and this survey method can be applied to the research of other animal diseases in Japan.     

Prevalence of bovine herpesvirus 1 (BHV-1) infection in Hungarian cattle herds.

Hungarian cattle herds were surveyed for bovine herpesvirus 1 (BHV-1) infection by ELISA of milk and serum samples. In 1993, 75% of the large cattle herds (consisting of more than 50 cattle) and all small herds (small-scale producers' stocks), while in 1997 90% of the small herds were included in the survey. In the case of large herds, 79.3% of the herds and 64.1% of the samples tested were found to be positive. Of the small herds, 13.5% and 15.7% tested positive in 1993 and 1997, respectively. The majority of large herds were Holstein-Friesian dairy stocks. Small herds with an infection rate markedly exceeding the average were found in those counties where the small herds had been in close contact with the large-scale farms, or where new herds were established by using animals of uncontrolled infectious bovine rhinotracheitis (IBR) status originating from large farms. Attention is called to the importance of maintaining the IBR-free status of small herds that constitute one-third of the Hungarian cattle population.     

Prevalence of serum antibodies to Mycobacterium avium subsp. paratuberculosis in cattle in Galicia (northwest Spain)

Prior to establishing a control and prevention program for Johne's disease in cattle in Galicia (northwest Spain), a survey was conducted to estimate the prevalence of the disease. For this survey, 61,069 animals of at least 1-year of age from 2735 randomly selected herds were bled and samples analyzed with a commercial ELISA. The estimated true individual-level prevalences – assuming the manufacturer's reported test sensitivity of 48.5% and specificity of 98.9% – were 3.02% in dairy cattle, 1.03% in beef cattle and 2.83% in animals from farms with both dairy and beef cattle. True herd prevalences (with herds declared positive if one or more animals tested positive) were 10.69% for dairy herds, 0% for beef herds and 2.71% for mixed herds. When herds were declared positive if at least two animals tested positive, true herd prevalences were 14.75% for dairy herds, 1.47% for beef herds and 12.01% for mixed herds. Assuming a higher specificity of 99.4%, true individual-level prevalences increased to 4.03% in dairy herds, 2.07% in beef herds and 3.84% in mixed herds. Herd prevalences were 27.77%/18.79%, 2.78%/2.40% and 5.70%/12.24% (using the one/two-animal cut-offs) in dairy, beef and mixed herds, respectively. In conclusion, these results seem to indicate that a small percentage of cows and a rather high percentage of dairy herds in this region are MAP-seropositive.     

Serological prevalence of Mycoplasma bovis infection in suckling beef cattle in France

The prevalence of Mycoplasma bovis infection in France was assessed by means of a serological survey of suckling beef cattle, using an ELISA. The survey included 824 randomly selected herds in eight French counties and a total of 32,197 animals more than one year old. In each county, the number of herds tested was determined statistically on the basis of the hypothesis that about 40 per cent of herds are infected. The proportion of herds containing at least one infected animal ranged from 28 to 90 per cent depending on the county. Among the 32,197 sera tested, the animal infection rate ranged between 2 per cent and 13 per cent. In infected herds, the average number of positive animals per herd was between 10 and 20 per cent, and the infection was unevenly distributed among the areas tested.     

Serological examination for evidence of infection with Hendra and Nipah viruses in Queensland piggeries

OBJECTIVE: To examine piggeries in Queensland for evidence of infection with Hendra virus and Nipah virus. DESIGN: A serological survey was designed to provide 99% confidence of detecting at least one infected pig herd in Queensland, assuming that for each virus, at least 5% of herds would have been exposed to virus and that at least 40% of the finisher pigs in these herds would have detectable antibodies to virus. PROCEDURE: A two stage sampling regimen was used. All samples were tested with serum neutralisation tests developed and performed at the Australian Animal Health Laboratory. RESULTS: There was no evidence of antibody to either virus in the 500 samples collected from 100 herds. CONCLUSION: The results of the survey support a case that commercial pigs in Queensland are free of both Hendra virus and Nipah virus infections.     

Seroprevalence of bluetongue serotype 8 in cattle in the Netherlands in spring 2007, and its consequences

A cross-sectional study was carried out in spring 2007, at the end of the first bluetongue outbreak season, to determine the geographical spread of bluetongue virus serotype 8 (btv-8) infection in cattle in the Netherlands and the consequences for some production parameters. Blood samples from cattle submitted to the laboratory of the Dutch Animal Health Service for other voluntary and obligatory health programmes were tested serologically for btv-8. In total, 37,073 samples were tested and 659 (1.78 per cent) were seropositive. The samples came from 5436 herds, of which 45 per cent of herds had only one sample submitted from them. The prevalence was highest in the south of the country, where the outbreak had started, and decreased towards the north. In 340 herds more than 50 per cent of cattle were tested, of which 156 herds were located in infected compartments, and in 37 of these herds (10.9 per cent) at least one positive cow was detected. The average within-herd prevalence in the 37 herds was 39.3 per cent: 2.2 per cent in 11 dairy herds, 68.4 per cent in 20 small-scale herds and 14 per cent in four suckler cow herds. The prevalence differed significantly between herd types but did not show a geographical trend. The average net return for milk production amounted to euro2417/cow/year and it decreased significantly on average by euro48/cow/year in the bluetongue-infected dairy herds during the bluetongue period. On the small-scale farms, the incidence of mortality increased by 3.2 (95 per cent confidence interval [CI] 1.2 to 9.1) times in the infected herds during the bluetongue period, but the voluntary culling rate decreased by a factor of 2.3 (95 per cent CI 1.1 to 4.8).     

Occurrence, isolation and serotyping of Erysipelothrix rhusiopathiae in cattle and pig slurry

In a survey on the occurrence of potential pathogenic bacteria in slurry, Erysipelothrix rhusiopathiae (E. rh.) was found in samples from 49 % of 84 cattle herds, 44 % of 32 pig herds, and 39 % of 67 cattle and pig herds. Among E. rh. isolates from 81 of the herds, 16 different serotypes were distinguished, including 1 serotype not previously described, which was designated serotype 23.Procedures of isolation and serotyping are presented and discussed, and the serotype distribution within the different herd categories is outlined.     

Herd prevalence of Salmonella enterica infections in Danish slaughter pigs determined by microbiological testing

As a part of a nationwide programme to survey and control salmonella in pig herds, a microbiological survey of 1363 pig herds was performed in Denmark. A total of 13 468 slaughter pigs were examined at slaughter by culture of 5 g of caecal contents. Overall, 30 different serotypes of Salmonella enterica were isolated from 832 pigs (6.2%). The predominant serotype was S. Typhimurium, comprising 536 (64.4%) of the isolates. Four hundred and forty-eight isolates of S. Typhimurium were examined by phage typing, resulting in detection of 17 different phage types (definitive types, DT) with DT12 being the most frequent (49.1%).

Salmonella enterica was found in 302 herds (22.2%), S. Typhimurium was found in 61.1% of these. 279 (23.1%) large herds (producing more than 2600 slaughter pigs per year) were found to be salmonella positive compared with 23 (14.7 %) small herds (annual production of 500 to 550 slaughter pigs). Practical constraints in the study design did not allow for a firm conclusion on the interplay among herd size, geographical location and occurrence of salmonella.

In 284 of 302 infected herds (94.0%) only one serotype was detected. Infections with two different serovars were seen in 18 herds (6.0%).     

The prevalences of Brachyspira spp. and Lawsonia intracellularis in Swedish piglet producing herds and wild boar population

The aim of the present study was to survey the prevalences of the enteric pathogens Brachyspira hyodysenteriae, Brachyspira pilosicoli and Lawsonia intracellularis in Swedish growing pigs and in the Swedish wild boar population and to relate these findings to clinical signs. The study included 105 randomly selected herds, constituting approximately one third of Swedish herds with a herd size of >100 sows. The herds were located all over the country. In these herds, growth promoters were not used and pigs sampled were not subjected to any medication. From each herd, samples were taken from 10 growing pigs aged 8-12 weeks, corresponding to approximately 2.5% of all growing pigs present in the herd at the sampling occasion. If possible, the samples were taken from pigs with diarrhoea. Forty-eight faecal samples and 71 rectal swabs were also taken from free-living wild boars (31 piglets, 19 growers and 21 adult animals) at shooting. The samples were analysed by culture and biochemical tests for the presence of Brachyspira spp. and by nested PCR for the presence of L. intracellularis. Brachyspira hyodysenteriae was not demonstrated in any sample. Brachyspira intermedia was detected in 22 samples originating from 15 herds, Brachyspira innocens/Brachyspira murdochii was detected in 370 samples from 82 herds and B. pilosicoli was detected in 134 samples originating from 34 herds. In 21 herds and in 534 samples, no Brachyspira spp. were detected. Lawsonia intracellularis was demonstrated in 285 samples from 50 herds. Further, 418 samples from conventional herds were negative with respect to L. intracellularis and in 345 samples the PCR had been inhibited. All samples from the wild boars were negative for Brachyspira spp., 12 of 48 samples were negative for L. intracellularis, and in 36 wild boar samples, the PCR was inhibited.     

Prevalence of bovine group A rotavirus shedding among dairy calves in Ohio.

Fecal samples were collected from 450 neonatal calves, ranging from 1 to 30 days old, between May, 1988 and May, 1989 to estimate the prevalence of bovine group A rotavirus in a stratified random sample of Ohio dairy herds. Calves were from 47 dairy herds chosen to be representative of Ohio herds. Bovine group A rotavirus was detected in fecal samples by a cell culture immunofluorescence test (CCIF) and ELISA. Of 450 samples tested, 46 (10%) were positive by CCIF and 67 (15%) were positive by ELISA. The agreement beyond chance between the 2 assays was good (kappa = 0.65). The overall prevalence rate of rotavirus shedding was 16.4% (74/450). Forty-three percent (29/67) of the samples positive by ELISA were subgroup 1, none were subgroup 2, and the remaining 57% (38/67) could not be assigned to either subgroups 1 or 2. Thirty herds (62.5%) had at least 1 group A rotavirus-positive calf (mean number of samples per positive herd = 12.4), and 17 herds (37.5%) had no rotavirus-positive calves (mean number of samples per negative herd = 6.0). A live oral rotacoronavirus vaccine was used in neonatal calves of only 1 herd and 3 of 17 (17.6%) calves from this herd were positive for group A rotavirus. The percentage of the rotavirus-positive fecal samples from all calves (n = 450) when stratified by fecal consistency was as follows: 28.3% (13/46) had liquid feces; 25.6% (10/39) had semiliquid feces; 23.4% (22/94) had pasty feces; and 10.7% (29/271) had firm feces.(ABSTRACT TRUNCATED AT 250 WORDS)     

Nationwide survey of antibodies to bovine coronavirus in bulk milk from Swedish dairy herds.

Bulk milk samples from 2236 dairy herds randomly selected throughout Sweden in proportion to region and herd size were analysed for antibodies to bovine coronavirus (BCV) in an ELISA. The results were expressed as optical density (OD) values and an OD > 0.04 was considered positive. Eighty-nine per cent of the samples were antibody-positive and 52 per cent had high levels of antibodies to BCV (an OD > 0.70). There were significantly higher OD values (P < 0.001) and fewer antibody-negative samples (P < 0.001) from larger herds than from smaller herds. There were also significantly higher OD values and fewer antibody-negative samples from herds in southern Sweden than from herds in northern Sweden (P < 0.001 and P < 0.001, respectively). These results indicate a higher frequency of BCV infections in larger herds and in herds in southern Sweden.     

A serological survey to determine the prevalence of infection with Treponema hyodysenteriae in Western Australia

A serological survey to detect antibody titres against Treponema hyodysenteriae was conducted on pigs from 106 herds in Western Australia. Titres indicating a positive result in the tests were determined by examining 400 sera from 4 herds known to be free of swine dysentery, and sera from immunised or experimentally infected pigs. Samples of serum from 40 bacon-weight pigs from each of the 106 herds were then collected at 2 abattoirs. Each serum was tested in enzyme-linked immunosorbent assays (ELISA) against the lipopolysaccharide of T hyodysenteriae of serogroups A, B and E, respectively. To assist in evaluating the test, 19 herds were resampled and retested, and faecal samples from 17 herds were cultured for T hyodysenteriae. Thirty-five of the 106 herds (33%) had serological evidence of infection when only one batch of sera from each herd was tested. The ELISA to detect T hyodysenteriae infection in herds using 40 sera was estimated as having a sensitivity of 77.3% and a specificity of 81.8% based on the owners' opinion of their herds disease status. Prevalence of infection within herds ranged from 2.5% to 47.5%, with a mean of 18%.