Great Britain has significantly decreased the rate of MAP infections among the country’s dairy herds. This ongoing effort is succeeding because of the involvement of dairy producers, veterinarians, dairy manufacturers, and governmental animal health authorities. The result is improved animal health, improved farm economics and efficiency, and improved food safety for consumers. A detailed analysis of data spanning 10 years has been recently reported in the journal Preventive Veterinary Medicine.
Figure: The pooled ATV (average test, meaning milk ELISA, value) for JD (Johne’s disease) tests carried out during ‘whole herd’ tests in the 154 studied herds, by year. NJMP Phase 1 and 2 refers to the National Johne’s Management Plan Phases 1 and 2.
The article is written for technical specialists and has an unusually high number of acronyms to keep straight. However, by all the many measures used to track MAP infections, dairy herds in Great Britain have fewer MAP-infected dairy cattle today than they did a decade ago.
ABSTRACT
Effective management of cattle infected with Johne’s Disease (JD) is crucial to minimizing transmission and within-herd prevalence. Within Great Britain (GB), the voluntary National Johne’s Management Plan (NJMP) requires farmers and a certified vet to conduct a risk assessment to determine the herd risk, examine the herd JD status and formulate a management plan. Individual milk ELISA tests for JD antibodies are widely used to monitor infection. The JD Tracker application, available within the dairy data management software InterHerd+ and other web-based environments, is being used by farmers and veterinarians to facilitate the practical use of milk ELISA data to aid JD-related management decisions. The JD Tracker application uses a herd’s milk ELISA data to calculate a collection of ‘JD parameters’ that are indicative of the current JD status of the herd alongside contemporary and retrospective drivers linked to transmission and maintenance of infection. Herein, we use milk ELISA data from 154 regularly testing herds to review the temporal trends in JD parameters from 2013 to 2022. Since 2015, JD Tracker parameters have improved in these herds, most notably average test value (ATV) and within-herd prevalence (%Pos30). Trends in driver parameters suggest that farmers are progressively less likely to serve repeat test-positive (J5) cows and are more readily removing them. The data also reveal that the burden of JD is disproportionately greater in herds with higher ATV. In 2022, the 25 % of herds with the highest ATVs accounted for 42 % of positive tests and 42 % of repeat ELISA positive (J5) cows. Retrospectively, it is not possible to identify with certainty factors that directly contributed to the trends in JD parameters, but it is notable that the introduction of the NJMP was coincided with the improving JD situation. In 2019, participation in the NJMP or an equivalent scheme became mandatory for dairy farms to be compliant with the food and farms standards assurance scheme Red Tractor, with the result that JD management plans are now completed by 95 % of UK dairy farms. As far as we know, the UK is unique in its development of a tool (the JD Tracker) which adds utility to milk ELISA data using specifically designed JD parameters. Anticipated further work includes the development of a national database of JD testing herds and application of the JD Tracker at national scale to enable more comprehensive industry-level monitoring of JD within GB dairy farms.
COMMENTS
This article demonstrates that Johne’s disease control is achievable at the national level when stakeholders at every level of the supply chain, including consumers (taxpayers), are engaged. Programs that depend too heavily on governmental funding often are unsustainable because of the long-term necessity of continued financial support in the face of declining budgets for animal health.