The DairyCo Mastitis Control Plan – The UK National Scheme
As in many other parts of the developed world, dairying in the UK has undergone a radical restructuring over the past 40 years. Total cow numbers have reduced, as have the number of producers, whilst cow yields have increased. In England and Wales there are approximately 10,500 producers milking 1.8 million dairy cows producing on average 7,600 litres of milk per year. From a level in excess of 600,000 cells/mL in the late 1960s, bulk milk somatic cell counts in milk sold off-farm have now, in 2013, fallen to an all-time low and are currently running below 200,000 cells/mL.
National Mastitis Control Schemes
National schemes, programmes and campaigns have been used for mastitis control in dairy cows for many years. An early example in the 1960s was the Five Point Plan in which a basic set of measures was proposed that were considered to have a beneficial effect on clinical and subclinical mastitis. At that time, control plans were relatively straightforward, because with mastitis incidence and prevalence at very high levels (e.g. in the UK the incidence rate of clinical mastitis was around 150 cases per 100 cows per year), and contagious pathogens being responsible for the majority of mastitis that occurred, the scope for improvement using relatively simple measures was huge. Since then, levels of production have escalated, cow genetics have progressed and management systems have changed dramatically, thus the management of mastitis has become much more challenging. In general, environmental pathogens have become increasingly important and the prevention of environmental infections is often more complicated than reducing the transmission of contagious pathogens; environmental management often requires more detailed, close-to-farm evaluations and farm-specific advice.
Implementing mastitis control on a national basis requires knowledge, motivation, widespread participation, excellent communication, financial backing, industry and political cooperation and, most of all, a dogged determination to succeed. Some very successful schemes have been set up in other countries, for example, Countdown Downunder (Australia), the SAMM Plan (now Smart SAMM, New Zealand), the Dutch Udder Health Program and the Norwegian Mastitis Control Program. A scheme was launched in Great Britain in 2009 led by a collaboration of the national dairy levy board (DairyCo) and a team of researchers and veterinary surgeons. This scheme was not proposed as the only or necessarily the ‘best way’ to approach mastitis control, but was developed to allow a coordinated approach to mastitis control on a national scale.
The history of mastitis control in the UK
The first coordinated approach to controlling bovine mastitis in the UK began in the 1960’s with the development of the Five Point Plan from research conducted at the National Institute for Research in Dairying at Reading. As the name suggests, the Plan was comprised of five key points, namely, the identification and treatment of clinical cases, routine antibiotic dry cow therapy for every cow at drying-off, post-milking teat disinfection, culling of persistently infected cows and regular maintenance of the milking machine.
Uptake of the plan resulted in rapid progress in the control of clinical and sub-clinical mastitis as illustrated in Figure 1. This came about primarily through better control of contagious mastitis pathogens (i.e. those adapted for survival within the host mammary gland). The incidence rate of clinical mastitis fell from more than 150 cases per 100 cows per year to just 40 cases per 100 cows per year between 1967 and 1982. At the same time, the national bulk milk somatic cell count reduced from over 600,000 cells/ml to 400,000 cells/ml. The introduction of EC Milk Hygiene Directive (92/46) in 1991, imposing an upper limit of 400,000 cells/ml in bulk milk for human consumption, coupled with incentives offered to dairy farmers to produce milk of higher quality with a low somatic cell count, further reduced the prevalence of infected cows in the UK.
somatic cell count from the early 1970s to 2011
- From the early 1980s until recently the incidence rate of clinical mastitis in the UK has been difficult to determine. Several small-scale studies between 1998 and 2002 estimated the mean figure at approximately 35 to 50 cases per 100 cows per year (not dissimilar to that seen 15 to 20 years earlier). These studies identified Escherichia coli and Streptococcus uberis as the most common causes of clinical mastitis, with contagious pathogens being significantly less important. These studies demonstrated what was being indicated anecdotally – that environmental pathogens were becoming more important in the aetiology of mastitis in the UK.
This increased perception of the importance of the environment in mastitis control led, in the late 1990s, to the Department for the Environment, Food and Rural Affairs introducing the ‘Six Point Plan’ for mastitis control, with the sixth point being the management of the cow’s environment.
The individual incidence rate of clinical mastitis cases (cases per
100 cows per year) from 97 dairy herds across England and Wales
In 2004 DairyCo, concerned about the lack of information about mastitis in the UK and a perceived lack of progress in its control, commissioned research to review mastitis in the UK and develop a national plan for mastitis control. This research surveyed clinical mastitis incidence and aetiology across almost 100 herds in the UK, revealing a significant proportion of herds experiencing very high rates of clinical mastitis (see above) and demonstrating a significant shift in clinical aetiology since earlier surveys as illustrated in Figure 3.
- Proportion of clinical mastitis cases by classical category during
the last 40 years
Development of the DairyCo Mastitis Control Plan
A major problem with research into endemic diseases such as mastitis is that their multi-factorial nature means that any control programme has to involve a number of simultaneous management changes. A change in just one risk factor alone may improve mastitis control only marginally, not at all or may even increase the risk of mastitis from a different pathogen. For example there is evidence in the literature to suggest that some control measures directed against contagious mastitis pathogens (those that spread from cow-to-cow) may in fact increase the risk of environmental mastitis.
Whilst there is an extensive literature identifying specific risk factors for, and interventions to control bovine mastitis, there was a need to test whether risk factors associated with clinical mastitis were indeed causal rather than explanatory and whether or not a control plan that used these risk factors could be implemented and be effective at reducing the incidence of mastitis in commercial herds in the UK.
To this end, a randomised clinical trial was carried out on 52 commercial dairy herds in England and Wales in 2004/5. The aim was to determine whether a well-specified mastitis control plan (The DairyCo Mastitis Control Plan), implemented in herds with an increased incidence of clinical mastitis, would reduce the incidence of disease as well as the incidence of increased somatic cell counts in individual cows. Two veterinary specialists (members of the Royal College of Veterinary Surgeons) developed a clearly defined plan for the diagnosis and control of bovine mastitis based on an extensive review of the research literature.
Twenty-six herds (intervention herds or Plan herds) were allocated at random to receive the Plan from the start of the study period, with the other 26 herds receiving the Plan after one year.
After one year, the incidence of cows affected with clinical mastitis had increased by 19% in control herds but had decreased by 4% in the intervention (Plan) herds. The proportional change in incidence of clinical mastitis in the individual herds is illustrated in Figure 4.
Figure 4: An illustration in the proportional change in incidence rate of clinical mastitis (IRCM) in the first year following the implementation of the Mastitis Control Plan. The intervention (Plan) herds are shown in red and the control herds are shown in blue
Results from statistical modelling (to include potential confounding factors) showed a significant 22% reduction in the proportion of cows affected with clinical mastitis on the intervention (or Plan) farms compared with the control farms. Significant reductions were also shown in the incidence of clinical mastitis and new infections as measured by change in somatic cell counts.
Further exploration of the study data demonstrated that the degree of compliance with the Plan recommendations had a significant impact on outcome as illustrated in Figure 5. The eight intervention herds with the highest level of compliance (>66% of recommendations implemented) made a total of 80 management changes, a mean of 10 per farm, compared to just 4.2 management changes for herds with the lowest level of compliance (<33% of recommendations implemented).
Figure 5: An illustration of the impact of differing compliance, in intervention herds, on the relative reduction in the incidence rate of cows affected (IRCA) with clinical mastitis
The principles of the DairyCo Mastitis Control Plan
The DairyCo Mastitis Control Plan is certainly not the only way to control bovine mastitis, but it aims to use research evidence wherever possible and involves all areas of farm management in a ‘manageable’ way. Recommendations are applied in a hierarchical manner according to both the robustness of the evidence to support their utility in mastitis control and based on the patterns of disease evident on the farm.
Farms are categorized according to the patterns of disease. This is based on both clinical mastitis and somatic cell count data, with the aim of defining both the main mode of transmission of mastitis, as either contagious or environmental, and the predominant source of new intramammary infection as either the dry or lactating periods. Following this categorization, recommendations are then made using the Plan with the aim of initiating a rolling process of review and refinement as outlined in Figure 6.
Figure 6: An illustration of the approach tot the implementation of the DairyCo astitis Control Plan
Rollout of the DairyCo Mastitis Control Plan
Following the initial research that led to the development of the Mastitis Control Plan, a pilot study was initiated with a small group of farmers and their veterinary surgeons. The lessons learned in this small pilot study were then applied as the scheme was launched nationally in 2009.
The rollout of the scheme involved the training of veterinarians and consultants in the principles and delivery of the Plan. This training was spread over two days separated by approximately 6 weeks. On the first day, delegates are introduced to the plan and the resources developed to assist the process and are then tasked to visit and begin implementation of the Plan on one farm with a view to discussing their experiences and approach when returning on the second day.
A number of paper and electronic resources as well as a website (www.mastitiscontrolplan.co.uk) and discussion forum were developed to support plan users. These included the electronic version of the Mastitis Control Plan, a cost calculator and decision support tools to inform treatment and culling decisions on the farm. In addition, a searchable database of licenced Plan Users is available in the form of an interactive map on the DairyCo website allowing farmers to identify practitioners trained in delivery of the Plan.
Open meetings and discussion groups are used by the DairyCo Extension officers to promote the plan to farmers and outcomes of the plan are supported by various other DairyCo publications.
Resources developed to support users in implementation of the DairyCo Mastitis Control Plan
In the initial three years of the rollout of the National Scheme Plan, users were provided with telephone support and help in interpreting data. They were also expected to attend a refresher course on a topic of their choice on an annual basis at which further in-depth training was offered. It also offered the opportunity to share experiences and enabled the organisers to collate feedback.
In the first three years, over 250 Plan Users were trained and a Plan was implemented on almost 1,000 dairy farms representing more than 10% of the total dairy cow population.
Figure 7: Interactive map of Plan Users available on the Mastitis Control Plan website
Patterns of disease in the national herd
Analysis of data from herds in the first three years of implementation of the Plan suggested that less than 10% of herds were experiencing problems associated with the contagious spread of mastitis pathogens. Instead, the vast majority were faced with the challenges of managing environmental mastitis. More in-depth analysis of those herds demonstrating environmental patterns of disease suggested that the primary source of new infection was the dry period in approximately 50% of cases and lactation in the remainder, with very few herds having mixed patterns of disease.
The impact of the DairyCo Mastitis Control Plan
Whilst it was acknowledged that it would be difficult to measure outcomes of Plan implementation when rolled out in a national scheme, data were collected prospectively from Plan users and processed electronically by the authors. Key performance indicators were developed in consultation with DairyCo which comprised incidence rates of clinical mastitis and apparent infection rates calculated from somatic cell count (SCC) data. Farms were monitored over time and the year before Plan implementation was considered the ‘baseline’ year for each farm to determine the Plan effect. Analysis of available data suggested that the reduction in mastitis appeared to be very similar to that found in the original development of the Plan and as in the original research success appeared to be clearly related to compliance with the recommendations as illustrated in Figure 8.
Figure 8: The impact of the mastitis control plan on new infection rates (as measured by SCC) in lactation in herds defined as having environmental, lactation based patterns of disease.
(DE FIGUUR IS TERUG TE VINDEN IN DE EXCELL-FILE)
The DairyCo Mastitis Control Plan – beyond the initial phase
Following the first three years of the national scheme, DairyCo has remained committed to developing and refining the Mastitis Control Plan. The authors remain involved, and whilst the level of support for Plan Users has inevitably reduced, a steady stream of new users are coming forward and the Plan continues to be implemented on farms on a regular basis. The year 2013 has seen a number of developments with Plan Users now being encouraged to submit their plans and supporting data (anonymously) to inform the on-going research at the University of Nottingham into factors influencing disease incidence on farms. In addition, late 2013 will see the first major update and revamp of the Plan with a refinement of the existing components and the integration of new research findings.
