Herd health status and management practices on 16 Irish suckler beef farms

Background

There have been few studies published internationally which document herd health management practices in suckler beef herds and no published Irish studies. The study objective was to document herd health status and management practices on sixteen Irish suckler beef herds over a two year period (2009–2010). The farms used in the study were part of the Teagasc BETTER farm beef programme. The mean (s.d.) herd size, stocking rate and farm size was 68 cows (27.6), 2.0 LU/ha (0.3) and 64.3 (21.6) adjusted hectares, respectively. Two questionnaires were designed; 1) a farmer questionnaire to collect information on farm background and current herd health control practices and 2) a veterinary questionnaire to collect information on the extent of animal health advice given by veterinarians to their clients and identification of any on-farm herd health issues.

Results

Dystocia, calf pneumonia, and calf diarrhoea, in that order, were identified as the primary herd health issues in these Irish suckler beef herds. In addition, substantial deficiencies in biosecurity practices were also identified on these farms.

Conclusions

The findings of this study may serve as the focus for future research in animal health management practices in Irish suckler beef herds.     

Farming practices in Sweden related to feeding milk and colostrum from cows treated with antimicrobials to dairy calves

Background

Milk produced by cows in receipt of antimicrobial therapy may contain antimicrobial residues. Such antimicrobial-containing waste milk must be withdrawn from human consumption and is therefore sometimes used as calf feed. Unfortunately, this approach might promote selection of antimicrobial resistant bacteria in the calves’ intestinal microbiota. The objectives of this study were therefore to obtain an overview of waste milk feeding practices on Swedish dairy farms and to investigate if these practices were associated with certain farm characteristics. A representative group of 457 Swedish dairy farmers participated in a web-based survey with questions about the use of colostrum and milk from cows treated with antimicrobials at dry off or during lactation, respectively, as calf feed.

Results

Colostrum (milk from the first milking after calving) and transition milk (milk from the second milking to the fourth day after calving) from cows treated with antimicrobials at dry off was fed to calves on 89% and 85% of the farms in the study, respectively. When antimicrobial therapy was given to cows during lactation, 56% of the farms fed milk that was produced during the course of treatment to calves, whereas milk that was produced during the subsequent withdrawal period was fed to calves on 79% of the farms. Surveyed farmers were less prone to feed such milk if the antimicrobial therapy was due to mastitis than other infections. In Sweden, a majority of antimicrobial treatments during lactation are systemic administration of benzylpenicillin and thus, the bulk of waste milk in Sweden is likely to contain residues of this drug. Feeding waste milk to calves was more common on non-organic farms, and on farms located in Southern Sweden, and was less common on farms with cows housed in cold free stalls barns.

Conclusions

Waste milk that may contain antimicrobial residues is, at least occasionally, used as feed for calves on a majority of surveyed Swedish dairy farms. Future work should focus on the effect of waste milk feeding on the occurrence of antimicrobial resistant bacteria in the calves’ intestinal microbiota.     

Disease screening profiles and colostrum management practices on 16 Irish suckler beef farms

Background

Calf output is a key element in determining the profitability of a suckler beef enterprise. Infectious agents such as Bovine Virus Diarrhoea (BVD) virus, colostrum management and parasitic challenge can all affect calf output. Prior to the national BVD eradication programme, there was little published information on either the prevalence or effect of BVD in Irish beef herds. There is little published information on colostrum management practices in Irish commercial beef herds and there have also been few studies published on the prevalence of liver fluke or rumen fluke infection in Irish beef herds. Sixteen farms participating in the Teagasc/Farmers Journal BETTER farm beef programme were used in this study. Fourteen herds were screened for the presence of BVD virus in 2010 using RT-PCR. In 13 herds, blood samples were collected from calves (2–14 days of age) in November 2011 - April 2012 to determine their passive immune status using the zinc sulphate turbidity (ZST) test, while in 12 herds, blood and faecal samples were taken in order to determine the level of exposure to gastrointestinal and hepatic helminths.

Results

The overall prevalence of BVD virus-positive cattle was 0.98% (range 0 - 3% per herd, range 0.6 - 3.0% per positive herd). Eighteen of the 82 calves (22%) sampled had ZST values less than 20 units (herd mean range 17.0 – 38.5 units) indicating a failure of passive transfer. The overall animal-level (herd-level) prevalence of liver fluke and rumen fluke infection in these herds was 40.5% (100%) and 20.8% (75%), respectively.

Conclusions

The potential costs associated with the presence of animals persistently infected with BVD virus through the increased use of antibiotics; the rate of failure of passive transfer of colostral immunoglobulins and the high prevalence of liver fluke infection in these herds highlight that some Irish suckler beef farms may not be realizing their economic potential due to a range of herd health issues. The use of farm-specific herd health plans should be further encouraged on Irish suckler beef farms.     

Comparison of Thoracic Auscultation,Clinical Score,and Ultrasonography as Indicators of Bovine Respiratory Disease in Preweaned Dairy Calves

Background

The diagnostic tools for bovine respiratory disease diagnosis include clinical inspection, thoracic auscultation, and ultrasonography.

Hypothesis

Thoracic auscultation and clinical examination have limitations in the detection of lung consolidation in dairy calves.

Animals

Prospective cohort of 106 preweaned calves from 13 different dairy herds (10 with a history of active bovine respiratory disease (BRD) in calves and 3 without suspected BRD problems).

Methods

Each preweaned calf was clinically inspected using the Wisconsin calf respiratory scoring chart (CRSC) and treatment history was noted. Systematic thoracic auscultation and ultrasonography then were performed, the latter focusing on lung consolidation. Mortality was recorded over a 30‐day period.

Results

A total of 56 of 106 calves had ultrasonographic evidence of lung consolidation. The sensitivity of thoracic auscultation to detect consolidation was 5.9% (range, 0–16.7%). Only 41.1% (23/33) of calves with consolidated lungs had been treated previously by the producers. When adding CRSC and previous BRD treatment by the producer, sensitivity of detection increased to 71.4% (40/56). The area under the receiver operating characteristics curve was 0.809 (95% CI, 0.721–0.879) for the number of areas within the lungs with consolidation and 0.743 (95% CI, 0.648–0.823) for the maximal depth of consolidation as predictors of death within 1 month after examination. These were not significantly different (P = .06).

Conclusions and Clinical Importance

This study shows that thoracic auscultation is of limited value in diagnosing lung consolidation in calves. Ultrasonographic assessment of the thorax could be a useful tool to assess BRD detection efficiency on dairy farms.     

Weaner production with low antimicrobial usage: a descriptive study

Background

Health, productivity and antimicrobial use in the production of pigs are expected to be interrelated to some extent. Previous studies on register-based data have investigated these correlations with a subsequent large variation residing at the farm level. In order to study such farm factors in more detail we designed an elaborate interview-guide. By in-depth interviews of farmers with well-managed 7–30 kg (weaner) productions we sought to describe a set of common key-factors characterizing their management practices. Identification of such common practices could be used in follow-up projects, investigating whether identified factors really are characteristic for good-practicing famers.

Results

Eleven farms were selected for a farm visit and in-depth interview. Participating farms used less antimicrobials than the national median (8.2 animal daily doses/100 weaners/day), had a mortality below the national average (2.9%) and an average daily weight gain above the national average (443 g/day). Similarities were observed among participating farms, including the sectioning of farms, use of all-in-all-out procedures with subsequent cleaning, purchasing 7 kg weaners from only one source, as well as active participation in management by a committed farm owner. Most farmers had a specific point of focus in their management, and were convinced that this was the reason for their success. This included; feeding, treatment strategy, refurbishment of facilities and presence in the shed.

Conclusion

According to register data, participating farms were alike; in the good league regarding use of antimicrobials, mortality and daily growth. However, on-farm interviews elucidated more heterogeneity among farmers than expected. Most of the farmers had a specific point of focus, which they considered to be crucial for their good results. These results indicate the importance of non-registerable factors, highlighting the value of qualitative study techniques in the understanding of human actions. Further studies on the effect of various farmer types are recommended.     

Nematode control in suckler beef cattle over their first two grazing seasons using a targeted selective treatment approach

Background

With concerns over the development of anthelmintic resistance in cattle nematode populations, we must re-examine our approach to nematode control in cattle. Targeted selective treatments (TST), whereby individual animals are treated instead of entire groups, are being investigated as an alternative. The study objective was to determine if anthelmintic usage could be reduced using a TST-based approach to nematode control in spring-born suckler beef cattle over their first and second grazing seasons (SGS) without affecting performance. In the first grazing season (FGS), 99 calves with an initial mean (s.d.) calf age and live weight on day 0 (June 28^th 2012) of 107 (23.1) days and 160 (32.5) kg, respectively, were used. The study commenced on day 0 when calves were randomised and allocated to one of two treatments; 1), standard treatment (control) and 2), TST. Control calves were treated subcutaneously with ivermectin on days 0, 41 and 82 in the FGS. All calves were treated with ivermectin on day 124 and housed on day 133. In the SGS, only heifer calves from the FGS were used and control heifers were treated with ivermectin on day 393. Animals were weighed, blood and faecal sampled every three weeks. The TST animals were treated with ivermectin if thresholds based on a combination of plasma pepsinogen concentrations, faecal egg count and/or the presence of Dictyocaulus viviparus larvae in faeces (FGS only) were reached.

Results

No TST calves reached the treatment threshold criteria in the FGS. The FGS average daily live weight gain (ADG ± s.e.m.) for control and TST group calves was 0.89 ± 0.02 kg and 0.94 ± 0.02 kg day⁻¹, respectively (P = 0.17). In the SGS, all heifers were treated with ivermectin on day 431 due to clinical signs of respiratory disease. The ADG for control and TST heifers from turnout on day 321 to day 431 was 0.90 ± 0.04 and 0.80 ± 0.04 kg day⁻¹, respectively (P = 0.03).

Conclusions

Spring-born FGS suckler beef calves require minimal anthelmintic treatment to maintain performance. In contrast, clinical parasitic disease may develop in the SGS unless appropriate anthelmintic treatment is provided.     

Determining the Prevalence and Seasonality of Fasciola hepatica in Pasture-based Dairy herds in Ireland using a Bulk Tank Milk ELISA

Background

Fasciola hepatica is a helminth parasite of global importance in livestock, with major economic impact. However information on F. hepatica infections in Irish pasture-based dairy herds is limited. Therefore this study was conducted in order to determine the prevalence, seasonality and management factors associated with F. hepatica. A total of 319 Irish dairy herds were selected for this study. Bulk tank milk (BTM) samples were collected from 290 dairy farms on a quarter year basis, while from a further 29 dairy farms BTM samples were collected on a monthly basis to provide a more detailed pattern of F. hepatica exposure in Irish herds. BTM samples were analysed using a commercially available F. hepatica antibody detection ELISA. Furthermore, within-herd prevalence of F. hepatica was assessed in a subset of these 29 herds (n = 17); both individual serum samples and bulk tank milk samples were collected.

Results

A within-herd prevalence of ≤ 50 % was found for herds with negative bulk tank milk samples. The mean prevalence of the 290 study herds was 75.4 % (Range 52 %–75.1 %), with the highest prevalence being observed in November (75.1 %). The seasonal pattern of F. hepatica shows elevated antibodies as the grazing season progressed, reaching a peak in January. A significant association was found between F. hepatica and age at first calving.

Conclusion

This study demonstrates that F. hepatica is present in a large proportion of Irish dairy herds and provides a basis on which control practices, particularly in adult dairy cows, can be reviewed.     

Prevalence and consequences of subacute ruminal acidosis in German dairy herds

Background

The prevalence and the clinical consequences of subacute ruminal acidosis (SARA) in dairy cows are still poorly understood. In order to evaluate the prevalence of SARA, 26 German dairy farms were included in a field study. In each herd, between 11 and 14 lactating dairy cows were examined for their ruminal pH using rumenocentesis. Milk production data and farm management characteristics were recorded. Each farm was scored for lameness prevalence among lactating animals, and body condition score was recorded three times four to five weeks apart in all animals examined. Farms were grouped on basis of ruminal pH and compared for lameness, body condition, milk production parameters and style of management. Animals were grouped on basis of their measured ruminal pH and compared accordingly for milk production parameters and body condition score.

Results

Of 315 cows examined, 63 individuals (20%) exhibited a ruminal pH of ≤ 5.5 at time of rumenocentesis. Of 26 farms examined, eleven farms had three or more of their cows experiencing a ruminal pH of ≤ 5.5 and were classified as likely experiencing subacute ruminal acidosis. These farms tended to be bigger than the others and offered less lying space to the lactating cows. There was no clear tendency regarding lameness. Among individual cows, animals with a low ruminal pH of ≤ 5.5 were found to be in significantly poorer body condition than animals with higher pH values (p < 0,05).

Conclusions

The study shows 11 out of 26 of herds likely experiencing SARA. Bigger herds tend to be at a higher risk for SARA, while individuals with low ruminal pH tend to be lower in body condition. The study points to the importance of management in preventing SARA.     

Validation of an Ultrasound Imaging Technique of the Tympanic Bullae for the Diagnosis of Otitis Media in Calves

Background

Otitis media is a common disease in calves that can be subclinical, making antemortem on‐farm diagnosis challenging.

Objectives

To evaluate the sensitivity and specificity of ultrasonography of tympanic bullae for the diagnosis of clinical and subclinical otitis media and to evaluate the reproducibility of the technique.

Animals

Forty calves 19–50 days of age were selected from a veal calf farm.

Methods

Prospective study. Ultrasonography was first performed on the farm by ultrasonographer A (US A). Ultrasonography was repeated by ultrasonographer A (US A'') and another ultrasonographer (US B) at the Centre Hospitalier Universitaire Vétérinaire. Images were later reread by both examiners and a diagnosis was recorded. The calves were euthanized and submitted for necropsy, and histopathologic diagnosis was used as the gold standard.

Results

Forty‐five bullae were affected by otitis media and 35 bullae were normal. Sensitivity and specificity of the ultrasound technique ranged from 32 to 63% and 84 to 100%, respectively, depending on the examiner and classification of suspicious ultrasonography results. Kappa analysis to evaluate interobserver agreement between A'' and B yielded a к value of 0.53. Agreement within the same examiner (A versus A'') yielded a к value of 0.48, and real‐time ultrasound versus rereading of recorded images for A'' and B yielded к values of 0.58 and 0.75, respectively.

Conclusions

Sensitivity and specificity of the ultrasound imaging technique are, respectively, low and high for diagnosis of clinical and subclinical otitis media in calves, with moderate reproducibility.     

Challenges for bovine viral diarrhoea virus antibody detection in bulk milk by antibody enzyme-linked immunosorbent assays due to changes in milk production levels

Background

Bovine viral diarrhoea (BVD) is considered eradicated from Denmark. Currently, very few (if any) Danish cattle herds could be infected with BVD virus (BVDV). The Danish antibody blocking enzyme-linked immunosorbent assay (ELISA) has been successfully used during the Danish BVD eradication program, initiated in 1994. During the last decade, the cattle herd size has increased while the prevalence of BVDV has decreased. In this study, we investigated how these changes could affect the performance of the Danish blocking ELISA and of the SVANOVIR^®BVDV-Ab indirect ELISA. The latter has successfully been used to eradicate BVD in Sweden.Data (2003–2010) on changes in median herd size and milk production levels, occurrence of viremic animals and bulk milk surveillance were analysed. Additionally, the Danish blocking ELISA and the SVANOVIR ELISA were compared analyzing milk and serum samples. The prevalence of antibody positive milking cows that could be detected by each test was estimated, by diluting positive individual milk samples and making artificial milk pools.

Results

During the study period, the median herd size increased from 74 (2003) to 127 cows (2010), while the prevalence of BVDV infected herds decreased from 0.51 to 0.02 %. The daily milk yield contribution of a single seropositive cow to the entire daily bulk milk was reduced from 1.61 % in 2003 to 0.95 % in 2010 due to the increased herd size. It was observed that antibody levels in bulk milk decreased at national level. Moreover, we found that when testing bulk milk, the SVANOVIR^®BVDV-Ab can detect a lower prevalence of seropositive lactating cows, compared to the Danish blocking ELISA (0.78 % vs. 50 %). Values in the SVANOVIR^®BVDV-Ab better relate to low concentrations of antibody positive milk (R² = 94-98 %), than values in the blocking ELISA (R² = 23–75 %). For sera, the two ELISAs performed equally well.

Conclusions

The SVANOVIR ELISA is recommended for analysis of bulk milk samples in the current Danish situation, since infected dairy herds e.g. due to import of infected cattle can be detected shortly after BVDV introduction, when only few lactating cows have seroconverted. In sera, the two ELISAs can be used interchangeably.     

Association of herd BRSV and BHV-1 seroprevalence with respiratory disease and reproductive performance in adult dairy cattle

Background

The aim of this study was to detect the associations between bovine herpesvirus 1 (BHV-1) status of a herd and respiratory disease (BRD) occurrence and reproductive performance in pregnant heifers and cows. The association between management-related factors and higher BRD occurrence was also estimated.

Methods

Serum samples, collected from cows and youngstock from 103 dairy cattle herds, were analyzed for antibodies against BHV-1, bovine respiratory syncytial virus (BRSV), bovine viral diarrhoea virus (BVDV), and Mycoplasma bovis. A questionnaire was used to collect data concerning herd management factors and reproductive performance, as well as the occurrence of clinical signs of respiratory disease in the last two years, as evaluated by the veterinarian or farm manager. Multiple correspondence analysis (MCA) and logistic regression analysis were performed to identify and quantify the risk factors.

Results

A low to moderate prevalence (1-49%) of BRSV antibodies among youngstock was associated with a high occurrence of respiratory disease (OR = 6.2, p = 0.010) in cows and in-calf heifers. Employees of the farm may participate in the spread of such disease. Larger herd size, loose-housing of cows, housing youngstock separately from cows until pregnancy, and purchasing new animals were factors possibly related to a high occurrence of respiratory disease symptoms in pregnant heifers and cows. The highest risk of abortions (> 1.3%) and increased insemination index (number of inseminations per pregnancy) (> 1.9) occurred in herds with a moderate prevalence of BHV-1 antibodies (1-49%) in cows.

Conclusions

BHV-1 was not associated with acute respiratory disease in adult dairy cattle, however was significantly related to reproductive performance. BRSV possesses the main role in respiratory disease complex in adult dairy cattle.     

Risk factors for post-weaning diarrhoea on piglet producing farms in Finland

Background

Post-weaning diarrhoea (PWD) is a significant gastrointestinal disease in pigs. It is considered a multifactorial disease associated with proliferation of enterotoxigenic Escherichia coli in the intestinal tract of affected pigs. The aim of this study was to analyse risk factors related to the occurrence of PWD on Finnish piglet producing farms.

Methods

The data of a follow-up study of 73 conventional piglet producing farms was used in the case-control study. The selection of the 41 PWD case and 28 control farms was based on the use of antimicrobials for treating diarrhoea in weaned pigs and the answers related to the occurrence of diarrhoea after weaning in the questionnaire. Four intermediate farms were excluded from the statistical analysis.Altogether 39 factors related to herd characteristics, weaner pig management and pig health were studied. The median number of sows was 59.0 (IQR = 44.0; 74.5) and 52.5 (IQR = 36.8; 61.5) on the case and the control farms, respectively.The significances of the univariable associations between the explanatory variables and the outcome variable were tested, and in the multivariate analysis quasibinomial generalized linear models were applied.

Results

An increased risk of PWD was associated with the regimen of twice a day feeding and feed restriction after weaning (P = 0.02; compared to feeding three or more meals a day or the use of ad libitum feeding) and with a higher number of sows on the farm (P = 0.02; risk increasing with increasing number of sows). Automatic temperature control was associated with a decreased risk of PWD (P = 0.03; compared to manual temperature control).

Conclusion

Twice a day feeding of newly-weaned pigs should be avoided if the amount of feed given is restricted. Variation in ambient temperature should be minimized in housing of newly-weaned pigs and this can be achieved by using automatic temperature control. With increasing number of sows in the herds the risk of PWD increases and more attention should be paid to prevention of post-weaning diarrhoea.     

A survey of management practices on Irish dairy farms with emphasis on risk factors for Johne’s disease transmission

Background

Johne’s disease (JD) is a chronic granulomatous enteritis affecting ruminants. A number of farm management practices are associated with increased risk of JD transmission. The aim of the current study was to document JD-related management practices currently employed on Irish dairy farms.Survey questions focused on calving area (CA), calf and manure management. Independent variables (region, calving-season, enterprise type, herd size and biosecurity status) were used to examine influences on JD associated dependent variables (survey questions). Additionally general biosecurity practices were also examined.

Results

Results showed management practices implemented by Irish dairy farmers pose a high risk of JD transmission. Of the farmers surveyed, 97% used the CA for more than one calving, 73.5% and 87.8% pooled colostrum and milk respectively, 33.7% never cleaned the CA between calving’s, and 56.6% used the CA for isolating sick cows. Survey results also highlighted that larger herds were more likely to engage in high risk practices for JD transmission, such as pooling colostrum (OR 4.8) and overcrowding the CA (OR 7.8). Larger herds were also less likely than smaller herds to clean the CA (OR 0.28), a practice also considered of risk in the transmission of JD.

Conclusion

Many management practices associated with risk of JD transmission were commonly applied on Irish dairy farms. Larger herds were more likely to engage in high risk practices for JD transmission. Control programmes should incorporate educational tools outlining the pathogenesis and transmission of JD to highlight the risks associated with implementing certain management practices with regard to JD transmission.

Electronic supplementary material

The online version of this article (doi:10.1186/s13620-014-0027-9) contains supplementary material, which is available to authorized users.     

Seasonal patterns of gastrointestinal nematode infection in goats on two Lithuanian farms

Background

This study investigated seasonal changes in naturally acquired gastrointestinal nematode (GIN) infections on two Lithuanian goat farms with different parasite control practices.

Findings

On both farms, nematode faecal egg counts (FEC) and larval cultures were obtained from 15 adult and 10 young goats at bi-weekly intervals from April 2012 to April 2013. Goats on farm A were dewormed with ivermectin (0.3 mg/kg body weight) in October/November 2012, whereas the animals on farm B were left untreated. Thirteen young goats were slaughtered in August/November 2012 and April 2013 and worm burdens in the gastrointestinal tract were enumerated. In goats from both farms, Teladorsagia, Trichostrongylus, Oesophagostomum, Chabertia and Haemonchus were the dominant GIN genera. Herbage contamination with infective third-stage larvae (L₃) peaked in July/August and resulted in high FEC in September/October. Parasitological examination at slaughter showed that Teladorsagia spp. and Haemonchus contortus survived the winter, both in the abomasal mucosa as adults and as early fourth-stage larvae (EL₄). Deworming on farm A significantly reduced FEC, especially of H. contortus, at the start of the grazing period compared with the untreated farm B (P < 0.05).

Conclusions

Goats were heavily infected with several GIN throughout the year. Strategic anthelmintic treatment during housing significantly reduced nematode egg output, in particular by H. contortus, at the start of the grazing season.     

Calf health and management in smallholder dairy farms in Tanzania

Smallholder farmers’ knowledge and practice of dairy calf management on 129 farms with calves less than 10 months of age in Southeastern and Southern Highland areas of Tanzania was assessed. The method of study included both a farm visit and completion of a questionnaire. Most of the farmers were female, with a primary level of education, and majority kept 1–3 milking cows that yielded 6–10 l milk/cow/day. Most of the calves were fed milk using a residual calf suckling system. Weaning age was 3–8 months. Overall, the body condition of the calves was poor, ranged from 1 to 2.5 with a mode of 2. The majority of the farmers believed that helminthosis was the most common disease condition affecting the calves; diarrhea was ranked as the second. Calf death was reported by 20% of the farmers to have occurred in their herd lasting the 2 years prior to the study. Calf body condition score was related to body weight for calves younger than 9 weeks, and older than 23 weeks of age, whereas no such relationship existed in the age group 9 to 23 weeks. The sex distribution was skewed with less male calves being older than 23 weeks. We hypothesize that male calves experience inferior management compared with female calves. This study demonstrates a low level of knowledge on, and poor practices of calf management among the surveyed farmers that suggest the need for educational intervention.     

Patterns of between-farm contacts via professionals in Sweden

Background

Infectious diseases of livestock have negative consequences for animal production as well as animal health and welfare and can be transmitted between farms via direct (live animal movements) as well as indirect (via physical vectors such as, people, transport vehicles and fomites) contacts. The objective of the study was to examine the travel patterns of professionals visiting Swedish farms (veterinarians, milk tanker drivers, artificial inseminators, maintenance technicians and livestock hauliers). This was done by obtaining records of the farms visited by a sample of professionals in the above categories in one week in January, one week in April, one week in July and one week in October in the Swedish counties Västerbotten, Södermanland, Västergötland and Skåne.

Results

There were twelve participating organisations, and data was provided for one to three individuals/vehicles/veterinary practices per professional category and per geographic region (except for dairy service technicians and livestock hauliers who did not provide data from all regions). There was a trend towards larger areas covered and smaller number of farms visited per week in the north, but exceptions occurred and there were regional variations. Generally, the greatest areas were travelled by milk tankers and livestock hauliers, and the profession travelling over the smallest areas tended to be the veterinarians. Milk tankers visited most farms per week, one milk tanker could visit between 23 and 90 farms per week and travel over areas between 717 km² and 23,512 km² per week.

Conclusions

Valuable insight into the travel patterns of Swedish professionals has emerged although the implications of the study largely concern highly infectious diseases. Movement of live animals pose the greatest risk for the spread of infectious animal diseases; however indirect contacts are important for many diseases. The results of this study indicate that in Sweden a highly contagious disease might spread over a large area in the time span of one incubation period, which ought to be kept in mind in case of an outbreak and in outbreak investigations. The difficulties in contacting some professionals visiting farms could be a problem in an outbreak situation.     

How milk-fed dairy calves perform in stable versus dynamic groups

The objective of the present field trial was to compare calf performance among pre-weaned calves in two different group housing systems, stable groups (“all in–all out”) and dynamic groups (continuous introduction). Performance data was collected from 484 calves randomly assigned to the two systems at six large (230–450 cows) commercial Danish dairy herds. All six farms had both systems simultaneously in the same stall, and under identical management and feeding regimes.Calves in stable groups had significantly higher daily live weight gain than calves in dynamic groups (870 vs. 810 g/days). The prevalence of both diarrhoea and respiratory disease were more than twice as high among calves in dynamic groups compared to calves in stable groups.     

Ultrasonographic examination of the forestomachs and the abomasum in ruminal drinker calves

Background

The study investigated the ultrasonographic appearance of the reticulum, rumen, omasum and abomasum of calves with ruminal drinking syndrome.

Methods

In ten milk-fed calves with ruminal drinking syndrome the reticulum, rumen, omasum and abomasum were examined by ultrasonography using a 5-MHz linear transducer before, during and after the ingestion of milk.

Results

The reticulum could be imaged in eight of ten calves before feeding. The reticular wall appeared as an echoic line, similar to mature cattle, and reticular folds were seen in eight calves. The reticular content appeared as echoic heterogeneous fluid. Reticular contractions were biphasic with 1.0 ± 0.38 contractions per minute. The rumen had a mean wall thickness of 2.1 mm dorsally, 3.5 mm at the level of the longitudinal groove, and 3.2 mm ventrally. The ventral sac of the rumen of all calves contained echoic heterogeneous liquid. During feeding the milk entering the rumen could be seen as hyperechoic liquid in five calves. The omasum was seen on the right side as a crescent-shaped line medial to the liver in seven calves. Only the omasal wall closest to the transducer was seen as an echoic line with a mean thickness of 2.7 mm. The ultrasonographic appearance of the omasum did not change during or after feeding. The abomasum was seen immediately caudal to the xyphoid on both sides of the midline before feeding. The mean length at the ventral midline was 22.2 cm. The ingesta were heterogeneous in all calves and the abomasal folds were distinct in eight. The mean lateral expansion of the abomasum from the ventral midline to the left and right varied from 8.7 to 13.8 cm and from 4.3 to 11.3 cm. The milk entering the abomasum was observed in all calves, and signs of milk clotting were seen in all calves 15 minutes after feeding.

Conclusion

This study showed that ultrasonography is useful for detecting milk in the reticulum and rumen of calves with ruminal drinking syndrome.     

Glutathione peroxidase (GPX) activity in blood of ewes on farms in different scrapie categories in Iceland

Background

Preliminary studies indicated decreased glutathione peroxidase (GPX) activity in blood of ewes on scrapie-afflicted farms. Other studies have shown decreased GPX activity in brain of prion-infected mice and in prion-infected cells in vitro. The aim of this study was to examine the GPX activity in blood as well as the distribution of GPX-activity levels from ewes on farms in scrapie-afflicted areas in Iceland.

Methods

Blood samples were collected from 635 ewes (non-pregnant [n = 297] and pregnant [n = 338]) on 40 farms in scrapie-afflicted areas during the years 2001–2005, for analysis of GPX activity. The farms were divided into three categories: 1. Scrapie-free farms (n = 14); 2. Scrapie-prone farms (earlier scrapie-afflicted, restocked farms) (n = 12); 3. Scrapie-afflicted farms (n = 14). For comparison, 121 blood samples were also collected from non-pregnant ewes on one farm (farm A) in a scrapie-free area (scrapie never registered). Chi-square test was used to test for normal distribution of GPX-results, and Kruskal-Wallis test to compare GPX-results between categories.

Results

The GPX-results appeared to be biphasically distributed in ewes in all three scrapie categories and on farm A. The presumptive breaking point was about 300 units g Hb^-1. About 30–50% of the GPX-results from ewes in all three scrapie categories were below 300 units g Hb^-1 but only about 13% of the GPX-results from ewes on farm A. The mean GPX activity was highest on farm A, and was significantly lower on scrapie-prone farms than on scrapie-free or scrapie-afflicted farms (non-pregnant and pregnant ewes: P < 0.005, respectively; non-pregnant and pregnant ewes combined: P < 0.0005).

Conclusions

1) the distribution of GPX-results in blood of Icelandic ewes apparently has a biphasic character; 2) the GPX-results were higher in ewes on one farm in a scrapie-free area than in ewes on farms in the scrapie-afflicted areas; 3) GPX-activity levels were significantly lowest on earlier scrapie-afflicted, restocked farms, which might have a bearing on the recurrence of sporadic scrapie on these farms; 4) further study on the possible role of GPX activity in the occurrence of scrapie in Iceland is warranted.     

Progression of Coxiella burnetii infection after implementing a two-year vaccination program in a naturally infected dairy cattle herd

Background

The high prevalence of Coxiella burnetii infection in dairy cattle herds recently reported and the long survival time of the bacterium in the environment pose a risk to human and animal health that calls for the implementation of control measures at herd level. This study presents the results of a 2-year vaccination program with an inactivated phase I vaccine in a Spanish dairy herd naturally infected with C. burnetii. Calves older than 3 months and non-pregnant heifers and cows were vaccinated in April 2011 and the farm was subsequently visited at a monthly basis for vaccination of recently calved cows and calves that reached the age of 3 months. Annual booster doses were given to previous vaccinated animals as well. The effectiveness of the vaccine was assessed in terms of level of C. burnetii shedding through milk and uterine fluids and environmental contamination as determined by polymerase chain reaction (PCR).

Results

The percentage of shedder animals through uterine fluids and milk progressively decreased, and C. burnetii DNA load in bulk-tank milk samples was low at the end of the study. The average seroconversion rate in not yet vaccinated animals, which acted as control group, was 8.6% during the first year and 0% in the second year. DNA of C. burnetii was found in aerosols and dust samples taken in the calving area only at the beginning of the study, whereas slurry samples remained C. burnetii PCR positive for at least 18 months. Multiple Locus Variable number tandem-repeat Analysis identified the same genotype in all C. burnetii DNA positive samples.

Conclusions

In the absence of any changes in biosecurity, the overall reduction of C. burnetii infection in animals to 1.2% milk shedders and the reduced environment contamination found at the end of the study was ascribed to the effects of vaccination together with the culling of milk shedders. Vaccination has to be planned as a medium-long term strategy to suppress risks of re-infection.