From March 23-25 Royal GD will be present at the annual conference of the Society for Veterinary Epidemiology and Preventive Medicine (SVEPM) in Belfast. Gerdien van Schaik, president of the SVEPM, will chair the conference and our experts Irene Bisschop, Anouk Veldhuis and Inge Santman-Berends will present their studies.
Irene Bisschop: ‘The association between longevity and animal health in Dutch dairy herds’
This study evaluated the association between longevity and cattle health. Anonymized near census data was available for 16,200 Dutch dairy herds (~98% of the dairy herds) between 2016 and 2020. Herds were divided into six groups based on their longevity i.e. high or low, increasing or decreasing, stable median longevity and varying longevity. Cattle health parameters were analysed with multivariable population-averaged models that included longevity and other management factors as explanatory variables. Herds with a high longevity were associated with lower mortality, a higher antibiotic use in cows and a higher percentage of cows with a high somatic cell count (HSCC). The latter can be explained by a larger share of older cows. Herds with a low longevity had a higher mortality, a lower percentage of HSCC cows, lower antibiotic use in cows and higher antibiotic use in calves. In conclusion, longevity was associated with cattle health.
Anouk Veldhuis: ‘Bayesian diagnostic test evaluation and true prevalence estimation of Mycoplasma bovis in dairy cattle’
The true prevalence of dairy cattle herds with M. bovis infections in the Netherlands is unknown. Previous attempts to estimate prevalences were hampered by the absence of a diagnostic test that was validated under field conditions. This study estimated sensitivity and specificity of two commercial serum ELISAs and the true M. bovis herd prevalence using different latent class models. A total of 7,305 serum samples from 415 randomly chosen dairy herds were collected in winter 2019 and investigated for presence of antibodies against M. bovis using the BIO-K-302 ELISA from Bio-X. Serum samples from 100 of these herds were also tested with a second ELISA from IDvet. A Bayesian latent class model using the paired test results estimated an BioX sensitivity of 15.8% (95% BPI; 13-19) and a specificity of 99% (95% BPI; 98-99). IDvet sensitivity and specificity was estimated at 94.3% (95% BPI; 91-97) and 99% (95% BPI; 98-99), respectively. Then, a hierarchical Bayesian logistic model, applied on test results of all 415 herds, estimated an apparent herd-level prevalence of 46.5% (95% BPI; 42-52) and a true prevalence of 74.7% (95% CI: 63-85). Large dairy herds and herds that introduced cattle from other herds had a higher probability of having seropositive cattle than smaller dairy farms or closed farms. The large difference in test sensitivity of the two tests is expected to be caused by time since infection. Bio-X only detects recent infections while IDVet also detects older infections.
Inge Santman-Berends: Sound-control: stimulating output-based surveillance
Within Europe, Royal GD undertakes a variety of forms of collaboration. This may be aimed at the development of new methodologies, while other projects may focus on the sharing of knowledger and encouraging collaboration, so-called COST Actions. One of these projects is SOUND control (Standardizing OUtput-based surveillance to control cattle Diseases of cattle in the EU).
SOUND control looks at the possibilities to evaluate the results of various animal disease control programmes in an output-based manner. Each country has its own control programme for endemic diseases such as bovine viral diarrhea (BVD) and infectious bovine rhinotracheitis (IBR) for example, tailored to the local situation. Read the article in Update magazine, edition: November 2021
More information: www.svepm2022.org