Heck cattle in the Oostvaardersplassen: risk for infectious diseases or not?

This article discusses risk analysis of infectious diseases in a cattle population. Heck cattle living in nature reserve 'De Oostvaardersplassen' were studied as an example of the risk analysis approach. Twenty-five adult cattle were tested for every infectious disease agent that the risk analysis indicated might be prevalent. All sampled cattle tested positive for Bovine Herpesvirus 1, whereas the prevalence of antibodies against other infectious disease agents was below the level that was assumed to be the threshold for spread of the disease to cattle in the surrounding areas. Risk management of infectious diseases was expressed in a so-called 'low-risk profile'. The risk of introduction or spread of infectious diseases was estimated to be very low as long as the population was kept strictly enclosed.     

Schmallenberg virus challenge models in cattle: infectious serum or culture-grown virus?

Schmallenberg virus (SBV), discovered in Europe in 2011, causes mild transient disease in adult ruminants, but fetal infection can lead to severe malformation in cattle, sheep and goats.To elucidate the pathogenesis of this novel orthobunyavirus, considerable efforts are required. A reliable and standardized infection model is essential for in vivo studies. In the present study, two groups of four cattle were inoculated with either serum passaged in cattle only or cell culture-grown virus. The replication of culture-grown SBV in cattle was reduced compared to virus inoculated via infectious serum. In a second experiment, the infectious serum was titrated in calves; the tested batch contained 10^2.83 infectious doses per mL. Hence, serum-borne virus that was only passaged in the natural host is a suitable option for a standardized SBV infection model.     

Reptile adenoviruses in cattle?

This paper describes a hypothesis on the origin of the members of the recently established adenovirus genus, Atadenovirus, invading cattle, sheep, deer, duck and poultry. Comparison of the phylogenetic trees of adenoviruses and their hosts suggests a very ancient but common origin for the atadenoviruses. The surprisingly large difference between these virus types and other adenoviruses infecting the same host can be easily understood by assuming their separate evolution in different hosts (e.g., in reptiles versus a coevolution with mammals and birds, respectively) followed by a later host switch.     

BSE, feed and cattle in Switzerland: is there a spatial relation?

Cross-contamination of cattle feed with meat and bone meal (MBM) allowed in feed for other species is regarded as the current hypothesis for the infection pathway of Bovine Spongiform Encephalopathy (BSE) cases occurring after the implementation of a ban on feeding MBM to cattle. This study was aimed at establishing a spatial relation between BSE cases in Switzerland and the findings of MBM in cattle feed. A cluster analysis and a cohort study were performed. Two hundred sixteen BSE cases born after December 1990 and detected until August 1st 2005, screening data of 504 feed producers between 1996 and 2001 and population data from the Swiss 2001 cattle census were included. The cluster analysis showed feed producer, positive for MBM contaminations in cattle feed, as possible cluster centres for BSE cases. In the cohort study, farms within a radius of 2 and 10 km around positive feed producers showed significantly higher odds to have a BSE case than the control group. The odds ratio and its 95% confidence interval were 2.23 (1.26-3.93) for the 2 km radius and 1.38 (1-1.9) for the 10 km radius. The results provide evidence for a spatial relation between cross-contamination and BSE occurrence. These findings support the hypothesis of cross-contamination to be an important route for BSE transmission after a feed ban.     

Prevalence of antimicrobial resistance among bacterial pathogens isolated from cattle in different European countries: 2002–2004

Background

The project "Antibiotic resistance in bacteria of animal origin – II" (ARBAO-II) was funded by the European Union (FAIR5-QLK2-2002-01146) for the period 2003–2005, with the aim to establish a continuous monitoring of antimicrobial susceptibility among veterinary laboratories in European countries based on validated and harmonised methodologies. Available summary data of the susceptibility testing of the bacterial pathogens from the different laboratories were collected.

Method

Antimicrobial susceptibility data for several bovine pathogens were obtained over a three year period (2002–2004). Each year the participating laboratories were requested to fill in excel-file templates with national summary data on the occurrence of antimicrobial resistance from different bacterial species.A proficiency test (EQAS – external quality assurance system) for antimicrobial susceptibility testing was conducted each year to test the accuracy of antimicrobial susceptibility testing in the participating laboratories. The data from this testing demonstrated that for the species included in the EQAS the results are comparable between countries.

Results

Data from 25,241 isolates were collected from 13 European countries. For Staphylococcus aureus from bovine mastitis major differences were apparent in the occurrence of resistance between countries and between the different antimicrobial agents tested. The highest frequency of resistance was observed for penicillin. For Mannheimia haemolytica resistance to ampicillin, tetracycline and trimethoprim/sulphonamide were observed in France, the Netherlands and Portugal. All isolates of Pasteurella multocida isolated in Finland and most of those from Denmark, England (and Wales), Italy and Sweden were susceptible to the majority of the antimicrobials. Streptococcus dysgalactiae and Streptococcus uberis isolates from Sweden were fully susceptible. For the other countries some resistance was observed to tetracycline, gentamicin and erythromycin. More resistance and variation of the resistance levels between countries were observed for Escherichia coli compared to the other bacterial species investigated.

Conclusion

In general, isolates from Denmark, England (and Wales), the Netherlands, Norway, Sweden and Switzerland showed low frequencies of resistance, whereas many isolates from Belgium, France, Italy, Latvia and Spain were resistant to most antimicrobials tested. In the future, data on the prevalence of resistance should be used to develop guidelines for appropriate antimicrobial use in veterinary medicine.     

Anthelmintic treatment and the suppression of egg production in gastro-intestinal nematodes of sheep and cattle: fact or fallacy?

Evidence for a temporary suppression of egg production in gastro-intestinal nematodes of sheep and cattle following anthelmintic treatment is reviewed and the possible relevance of this phenomenon to the appropriate sampling time in the faecal egg count reduction test is discussed. The results of this review suggest that if such suppressive effects do occur in sheep nematodes, then they are unlikely to be of much practical significance and that little benefit would be derived from extending the post-treatment sampling interval beyond 10 days. For cattle nematodes, however, the issues are less readily obvious but indicate, at least when testing for resistance to persistent anthelmintics, that adoption of a longer post-treatment interval might be advisable.     

Where do we go in protection against pathogens?

A few reflections are made on the future strategies and approaches for combating infectious diseases of livestock, keeping into consideration public concern on food quality and availability. The policy of eradication of pathogens/diseases instead of vaccination has rendered livestock naive to certain pathogens and as a consequence susceptible to epidemic outbreaks, even more so as we have to conclude that outside attack is quite often difficult to control. Therefore, immunoprophylactic measures in livestock remain top priority and will in the future focus more on the induction of mucosal immunity and the activation of innate immunity.     

Cooperia punctata: effect on cattle productivity?

Cooperia spp. have become the most prevalent parasites in United States cow/calf operations as observed in the USDA NAHMS (National Animal Health Monitoring System) Beef Cow/Calf survey in 2008. This is at least in part due to the widespread use of macrocyclic lactones that have recently been shown to have a reduced activity against these parasites. The effects of Cooperia spp. on cattle productivity are largely unknown. This study was conducted to assess their effect upon cattle housed under conditions found in American feedlots. Two hundred yearling calves (average weight 460 lb/209 kg) were acquired from northwestern Arkansas and northeastern Oklahoma and were vaccinated and dewormed upon arrival at the feedlot. Animals were comingled and preconditioned for approximately one month, and were fed a standard growing ration throughout the study. Calves were randomly divided into two groups (n=80, infected and control) and each group was further divided into two replicate pens (n=40). Calves from the two infected pens were orally inoculated with a gavage of 1 × 10(5) and 0.825 × 10(5) infective larvae of a recent isolate of Cooperia punctata on day 0 and 14, respectively, with the two control pens receiving a similar volume of tap water. Data collected included biweekly fecal egg counts, daily individual feed consumption and weight gain over the 60-day test period. The presence of C. punctata (>99% of recovered worms) was confirmed by necropsy and recovery from the small intestine on days 35 and 60 post infection (PI) in a subset of animals. Egg counts were positive by day 14 PI and remained at numbers similar to values seen in field studies. The control group gained weight 7.5% more rapidly (p=0.02) than infected animals (3.24 lb/1.47 kg per day vs. 3.0 lb/1.36 kg per day, respectively). The Cooperia-infected calves also consumed 1.5 lb (0.68 kg) less dry feed per day than the control animals (p=0.02). These data suggest that C. punctata has a deleterious effect on both appetite and nutrient uptake or utilization. At necropsy (days 35 and 60), the draining mesenteric lymph nodes of infected animals were increased in size and the small intestinal mucosa was thickened and covered with a thick layer of mucus in the infected animals. The most prominent histological changes in the Cooperia- infected animals included a moderate increase in the number of intraepithelial lymphocytes and globule leukocytes, as well as aggregates of eosinophils within the lower lamina propria. The only significant difference was an increase in the goblet cell density at day 60. Anthelmintic sensitivity/resistance of the Cooperia isolate used was determined by treatment of one pen of infected calves with a macrocyclic lactone and the other pen with a benzimidazole at the completion of the study. The macrocyclic lactone treatment (n=40) did not remove the parasites (FECRT=8.8%), while treatment with a benzimidazole was very effective (FECRT=98.1%). This study demonstrated that C. punctata has a significant effect on cattle productivity, both reduced weight gain and decreased feed intake compared to controls.     

Rumenocentesis: a suitable technique for analysis of rumen juice pH in cattle?

In the United States, rumenocentesis has been recommended especially for early diagnosis of subacute rumen acidosis (SARA). The objective of the current study was to evaluate health risks due to the technique ofrumenocentesis and to measure pH in ruminal juice using a commercial indicator paper (Pehanon) and a pH electrode (reference method). After 11 dairy cows underwent rumenocentesis, the clinical status of those animals was evaluated daily, and cows were slaughtered as well as pathologically--anatomically examined on day 7. During the observation period, the following pathological clinical signs were evident: forced inspiration (3 cows), transient episode of hyperthermia (2 cows), increased tension of the abdominal wall (8 cows) and positive foreign body tests (3 cows). One cow had to be culled on day 7 because of severe generalised septic peritonitis spreading from the site of rumenocentesis. At slaughter, hematoma formation in the area of the puncture site was found in 9 out of 10 cows. It was concluded that the severe complications encountered with this technique do not legitimate rumenocentesis as a routine procedure for collection of rumen juice samples in cows under Swiss conditions. The correlation between the pH reference method and the commercial indicator paper was the high (r = 0.926).     

[The role of reproductive biology in SDGs] Global warming and cattle reproduction: Will increase in cattle numbers progress to global warming?

The livestock industry produces a large amount of greenhouse gases (GHG) that cause global warming. A high percentage of GHG emissions are derived from cattle and has been suggested to be a factor in global warming. With the global increase in the consumption of livestock products, the number of farm animals has increased. In addition, the reduction in productivity and reproductive capacity of cattle has resulted in accelerated GHG emissions. In a high-temperature environment, the pregnancy rate decreases, leading to an increase in animals that do not contribute to production. Consequently, GHG emission per unit product increases, thereby accelerating global warming. To reduce this environmental impact, it is important to improve the breeding efficiency of cattle by the use of reproductive technology and, thus, reduce the number of non-productive animals. Thus, reproductive biology plays a major role in mitigating global warming related to the livestock industry.     

Does reactive badger culling lead to an increase in tuberculosis in cattle?

The conclusion from the randomised badger culling trial was that localised badger culling not only fails to control but can actually increase the incidence of bovine tuberculosis in cattle. Professor Simon More and colleagues from University College Dublin question that conclusion, arguing that the data do not provide sufficient evidence to rule out alternative hypotheses.     

The cattle major histocompatibility complex: is it unique?

Major histocompatibility complex (MHC) class I genes encode highly polymorphic molecules that are expressed on virtually every cell type, and have been identified in all but the most primitive vertebrates. They play a number of crucial roles in the immune response to infectious disease. Most information regarding MHC genes has been generated from humans and mice but, because of the great variability found in the MHC system, it is not always possible to extrapolate from these to other species. Many strategies have evolved to maximise the ability of the MHC to protect individuals and populations against pathogens. Cattle MHC class I genes exhibit a number of unusual features. Evidence from mapping studies, haplotype and phylogenetic analyses suggests the presence of six classical class I loci, in contrast to the more usual two or three, and these are expressed in various combinations of one, two or three on different haplotypes. Although it remains difficult to assign alleles to loci, it appears that none of the loci are expressed on all haplotypes. There is currently limited information relating to polymorphism, but various approaches suggest diversity is high, and may vary between breeds/populations. Functional consequences of variable MHC haplotype composition are discussed. Identifying unique features of the MHC in cattle will lead to new insights into evolution of the immune system.