B Catry

Risk factors for ceftiofur resistance in Escherichia coli from Belgian broilers.

A cross-sectional study on 32 different Belgian broiler farms was performed in 2007 and 2008 to identify risk factors for ceftiofur resistance in Escherichia coli. On each farm, one E. coli colony was isolated from 30 random birds. Following susceptibility testing of 14 antimicrobials, an on-farm questionnaire was used to obtain information on risk factors. Using a multilevel logistic regression model two factors were identified at the animal level: resistance to amoxicillin and to trimethoprim-sulfonamide. On the farm level, besides antimicrobial use, seven management factors were found to be associated with the occurrence of ceftiofur resistance in E. coli from broilers: poor hygienic condition of the medicinal treatment reservoir, no acidification of drinking water, more than three feed changes during the production cycle, hatchery of origin, breed, litter material used, and treatment with amoxicillin. This study confirms that not only on-farm antimicrobial therapy, but also management- and hatchery-related factors influence the occurrence of antimicrobial resistance.

Prevalence of respiratory pathogens in diseased, non-vaccinated, routinely medicated veal calves

The prevalence of respiratory pathogens in diseased veal calves was determined in 24 respiratory disease outbreaks in 15 herds in Belgium. Bacteria were cultured from nasopharyngeal swabs and seroconversion against viruses and Mycoplasma bovis was determined on paired sera. At the individual calf level, Mycoplasma species, Mannheimia haemolytica and Pasteurella multocida, were isolated from 70.5 per cent, 21.5 per cent and 26.0 per cent of swabs, respectively. At the herd level, the presence of M bovis could be confirmed in 84.6 per cent of the herds examined. Seroconversion against bovine viral diarrhoea virus (BVDV) was present in 71.4 per cent of herds, parainfluenzavirus type 3 in 53.3 per cent, bovine respiratory syncytial virus in 40.0 per cent, bovine adenovirus type 3 in 46.7 per cent, bovine coronavirus in 30.0 per cent, and bovine herpesvirus type 1 in 26.7 per cent. At postmortem examination, Mycoplasma species could be cultured from 61.9 per cent of pneumonic lungs (n=21). Sixty per cent of calves tested were positive for BVDV (n=20), and 20.0 per cent were positive for bovine respiratory syncytial virus (n=16).

Efficacy of metaphylactic florfenicol therapy during natural outbreaks of bovine respiratory disease.

The efficacy of an injectable formulation of florfenicol (300 mg/mL) as metaphylactic control of naturally occurring bovine respiratory disease (BRD) was evaluated in two double-blind randomly controlled field studies on two Dutch veal calf herds (A and B). Cattle aged not older than 3 months and in the direct presence of calves with clinical respiratory disease were randomly allocated to treatment with 40 mg/kg florfenicol subcutaneously (s.c.) a positive control treatment (12.5 mg/kg tilmicosin p.o. twice daily for five consecutive days in herd A, and 12.5 mg/kg doxycycline p.o. twice daily for five consecutive days in herd B), or a negative control (one placebo saline s.c. administration on D0). The predominant respiratory pathogens present in pretreatment respiratory samples from affected animals were Mycoplasma bovis and Pasteurella multocida in outbreaks A and B, respectively. Metaphylactic administration of florfenicol resulted in a statistically significant weight gain, decreased rectal temperature for five consecutive days after treatment and decreased metaphylactic failure percentages compared with both positive and negative control groups. In summary, these studies demonstrated that a single s.c. injection of florfenicol is effective and practical for control of the bacterial component of BRD in veal calves.

Flux-conservative thermodynamic equations in a mass-weighted framework

A set of equations, ready for discretization, is presented for the purely thermodynamic part of atmospheric energetics along a vertical column. Considerations of kinetic energy budgets and detailed turbulence laws are left for further study. The equations are derived in a total mass-based framework, both for the vertical coordinate system and for the conservation laws. This results in the use of the full barycentric velocity as the vector of advection. Under these conditions, the equations are derived from first principles on the basis of an a priori defined set of simplifying hypotheses. The originality of the resulting set of equations is twofold. First, even in the presence of a full prognostic treatment of cloud and precipitation processes, there exists a flux-conservative form for all relevant budgets, including that of the thermodynamic equation. Secondly, the form of the state law that is obtained for the multiphase system allows the flux-conservative form to be kept when going from the hydrostatic primitive equations system to the fully compressible system and projecting then the heat source/sink on both temperature and pressure tendencies.

A new sub-grid scale lift formulation in a mountain drag parameterisation scheme

A new sub-grid scale lift formulation in a mountain drag parameterisation scheme is presented. The main novelty is a new approach to make the lift force act on an estimate of the geostrophic wind vector (instead of acting on the local near-surface wind vector). The goal of this new formulation is to avoid the envelope orography which is otherwise still needed in the ALADIN/ARPEGE Numerical Weather Prediction (NWP) model. The validation of this new lift formulation inside the ARPEGE/ALADIN parameterisation for sub-grid scale orographic effects takes place on three prediction scales with their proper tools: (1) semi-idealised tests performed by ALADIN on an idealised flow over a complex orography to yield momentum budgets; (2) regional scale tests using the operational Central European version of ALADIN to produce verification scores over Central Europe; and (3) global scale tests using the ARPEGE-NWP model to render statistically significant scores over the different continents. The new lift formulation is able to mimic the additional change in wind direction due to an envelope orography, while avoiding its unfavourable effects e.g. on the simulated precipitation. The updated parameterisation scheme has become resolution independent and the impact of the parameterisation disappears somewhere between a horizontal mesh size of 2.5 and 5 km. Finally, the operational performance of the new scheme in the ARPEGE/ALADIN system is demonstrated.

Fatal meningitis in a calf caused by Mannheimia varigena.

n Abstractn n n Mannheimia varigena was identified as the etiologic agent of meningitis in a young Belgian White Blue heifer calf. Species identification of the bacterium was done by phenotyping and molecularly confirmed by tDNA-PCR. Standard bacteriological examination might fail to differentiate species belonging to the genus Mannheimia.n n

Hydrallantois in the mare--a report of five cases.

Hydrallantois in the mare is a very rare condition, and clinical reports help to gather information to elucidate its pathogenesis, treatment options and prognosis. Five different cases of hydrallantois in the mare are reported in this article, all with the involvement of placentitis. The five mares were presented because of acute distention of the abdomen, dyspnoea, stiff gait and a lack of appetite. After a gradual release of the excessive amount of allantoic fluid, an abortion was induced in all five mares. The foals were either born dead or euthanized. The mares recovered quickly. One mare conceived within the same season, one remained barren despite several cycles of natural breeding, and no data were available on the other three mares. In this series, the condition is reported for the first time in two Shetland ponies, both pregnant with foals sharing a close genetic background. In both cases, the condition led to hyperlipidemia. The condition as it occurs in nulliparous mares is also discussed. Finally, the possible involvement of placentitis in the pathogenesis is emphasized.

An Interlaboratory Trial to Assess Repeatability and Reproducibility of Microbiological Procedures for Diagnosing Intramammary Infections in Dairy Cows

An interlaboratory trial was organised to assess the effect of bacteriological procedures on the repeatability and reproducibility of diagnosing intramammary infections in dairy cows. Forty milk samples (15 were duplicates) of which the majority were from quarters with an elevated somatic cell count (CMT positive) were distributed to 6 laboratories in Flanders (Belgium). Isolation procedure guidelines mentioned a volume of 0.01 ml of milk to be plated on an a-selective blood agar (5% bovine blood) with a standardised loop. Reading was performed after 24 and 48 hours of incubation at 37°C. Final results of species identification were reported using the following codes: (1) beta-hemolysin producing staphylococci, (2) other staphylococci, (3) streptococci, enterococci, aerococci, lactococci, (4) Gram negatives (5) Corynebacterium species (6) others (7) contaminant (8) contaminated (more than 2 different species) and (9) negative. Additionally, if 20 or less colony forming units (CFU) were isolated the exact number was reported. Otherwise colony count was reported as +. Repeatability was evaluated on the 15 duplicate milk samples. Kappa statistic was calculated to assess species identification repeatability and the coefficient of variation was calculated to assess colony count repeatability. Reproducibility was evaluated on the 25 single milk samples. Pairwise kappa statistic was calculated to assess species identification reproducibility. The geometric mean colony count (GMCC) per laboratory was calculated on these samples for which all laboratories reported the same identification code (including negative samples). Kappa statistic calculated on the 15 duplicate milk samples varied from 0.68 to 0.83, indicating a good (>0.6) to very good (>0.8) species identification repeatability. Coefficients of variation varied from 26.7 to 94.0%, indicating poor colony count repeatability. Pairwise kappa statistics between laboratories varied from 0.28 to 0.75. This large variation could be explained by the large variation of GMCC (0.14 1.54 CFU / 0.01 ml). The pairwise kappa statistic was low between laboratories with a large difference in GMCC and high between laboratories with a small difference in GMCC. Also, the smaller the GMCC the higher the proportion of negative results and the larger the GMCC the higher the proportion of samples with 2 or more than 2 different species. In conclusion, species identification repeatability was good but colony count repeatability and reproducibility were poor. The poor reproducibility could be explained by the differences in GMCC between laboratories. Since the number of CFU is associated with the plating volume, colony count repeatability and reproducibility could be improved by improving standardisation of plating volume procedures. Abstracts – Poster presentations at 11th ICPD 277