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Completeness of the Disease Recording Systems for Dairy Cows in Scandinavia

30 September 2012

Disease-recording systems in Denmark, Finland, Norway and Sweden are designed to ensure that the data for veterinary-visited cases is complete but researchers there found that is not the case for clinical mastitis in Nordic countries, leading them to conclude that the number of clinical mastitis cases in dairy cows is underestimated.

In the Nordic countries, Denmark, Finland, Norway and Sweden, the majority of dairy herds are covered by disease recording systems, according to Cecilia Wolff of the Swedish University of Agricultural Sciences and co-authors there and at the Norwegian School of Veterinary Science, the University of Copenhagen, the University of Helsinki and Sweden's National Veterinary Institute. In a paper published recently in BMC Veterinary Research, they explain that the recording systems are generally based on veterinary registration of diagnoses and treatments.

Disease data are submitted to the national cattle databases where they are combined with, for example, production data at cow level, and used for breeding programmes, advisory work and herd health management.

Previous studies have raised questions about the quality of the disease data, the researchers say, and the main aim of their study was to examine the country-specific completeness of the disease data, regarding clinical mastitis diagnosis, in each of the national cattle databases. A second aim was to estimate country-specific clinical mastitis incidence rates.

Over four months in 2008, farmers in the four Nordic countries recorded clinical diseases in their dairy cows. Their registrations were matched to registrations in the central cattle databases.

The country-specific completeness of disease registrations was calculated as the proportion of farmer-recorded cases that could be found in the central database. The completeness (95 per cent confidence interval) for veterinary-supervised cases of clinical mastitis was 0.94 (0.92, 0.97), 0.56 (0.48, 0.64), 0.82 (0.75, 0.90) and 0.78 (0.70, 0.85) in Denmark, Finland, Norway and Sweden, respectively.

The completeness of registration of all clinical mastitis cases, which includes all cases noted by farmers, regardless of whether the cows were seen or treated by a veterinarian or not, was 0.90 (0.87, 0.93), 0.51 (0.43, 0.59), 0.75 (0.67, 0.83) and 0.67 (0.60, 0.75), respectively, in the same countries.

The incidence rates, estimated by Poisson regression in cases per 100 cow-years, based on the farmers' recordings, were 46.9 (41.7, 52.7), 38.6 (34.2, 43.5), 31.3 (27.2, 35.9) and 26.2 (23.2, 26.9), respectively, which was between 20 per cent (DK) and 100 per cent (FI) higher than the incidence rates based on recordings in the central cattle databases.

Wolff and co-authors concluded that the completeness for veterinary-supervised cases of clinical mastitis was considerably less than 100 per cent in all four Nordic countries and differed between countries. Hence, the number of clinical mastitis cases in dairy cows is underestimated. This has an impact on all areas where the disease data are used.

Reference

Wolff C., M. Espetvedt, A-K. Lind, S. Rintakoski, A. Egenvall, A. Lindberg and U. Emanuelson. 2012. Completeness of the disease recording systems for dairy cows in Denmark, Finland, Norway and Sweden with special reference to clinical mastitis. BMC Veterinary Research, 8:131. doi:10.1186/1746-6148-8-131

Further Reading

You can view the full report (as a provisional PDF) by clicking here.


September 2012

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