My approach to reducing clinical mastitis

This is the first of two articles on approaches to reducing clinical mastitis and somatic cell counts that this author has used for many years. It has proved successful provided the farmer engages in the process. Of course, there are other successful approaches that can be taken. This article will not discuss Mycoplasma or Prototheca mastitis.

Clinical mastitis should be reduced for many reasons; improving animal welfare as it is a very painful condition, reduce medicine use especially antibiotics, protect milk quality (somatic cell count, Bactoscan and medicine residues) and for economic reasons as mastitis is an expensive disease.

There are many dairy herds that have low levels of clinical mastitis. Mastitis can be measured using the percent of the herd affected per month or the mastitis rate which is the number of cases per 100 cows per year where one case is one quarter infected once. This author prefers the mastitis rate as an easy way to quantify disease.

Some herds with excellent management have a mastitis rate as low as 10 to 15. The target is often quoted as 30. Targets should be set for individual herds and based on what is an acceptable and achievable level of disease.

There are many herds that still have high mastitis rates and may not be aware that this is a problem especially if their mastitis data is not analysed. Some farmers accept higher rates while others are constantly looking at ways to reduce incidence.

Causes of mastitis – Mastitis can be broken down into various categories;

• clinical and subclinical
• Contagious and environmental
• Lactation period infections (LPI) and dry period infections (DPI)

Clinical mastitis is mainly caused by environmental mastitis, such as coliforms and Streptococcus uberis. Staphylococcus aureus can cause clinical mastitis, but the importance of the environmental bacteria has increased. Levels of Staph. aureus and other contagious bacteria have decreased as dairy companies require lower cell counts.

The environment is the reservoir of infection with environmental mastitis. Infection can be transferred onto the teats at three different times;

1. Between milkings if the cows are lying in dirty conditions or have faecal splashing up against teats after coming out of the parlour
2. During milking if there is poor teat preparation or poor hygiene
3. During the dry period

Coliform infections mainly cause clinical mastitis while Strep. uberis causes both clinical and subclinical mastitis. Both can cause lactation and dry period infections. Staph. aureus is contagious, causes clinical and subclinical mastitis and enters only during lactation.

Practical steps to control clinical mastitis

1. Accurate diagnosis of the cause of clinical mastitis
2. Review current mastitis management
3. Agree and implement a control plan
4. Monitor and review progress

1. Accurate diagnosis of the cause of clinical mastitis

Individual farms can have a combination of mastitis problems. It is essential that the specific mastitis problem is properly identified. This requires data analysis and bacteriology testing. This approach is no different to a modern motor car being plugged into a computer at the garage to a precise diagnosis of an engine problem.

Most progressive dairy farmers keep computerised records allowing in-depth analysis at the touch of a button. It’s advisable to check accuracy of records as if these are incomplete then data analysis could be misleading. Data analysis is invaluable for identifying the cases of clinical mastitis. Areas that should be examined include the following.

Quantify levels of clinical mastitis using the mastitis rate or percent of cows with mastitis per month. Is the rate high, on target or low? Some farmers with low rates want to reduce this further.

Herd cell count. If the herd cell count is low, for example under 150,000/ml, this suggests that there is a low level of contagious mastitis present and so clinical cases are most likely due to environmental bacteria.

Percent of cows affected. If over 25% of the herd has had one or more cases of clinical mastitis this suggests problems with environmental mastitis.

Percent of cows with clinical mastitis within 30 days of calving. Dry period infections are suspected if more than 8% of cows have clinical mastitis within 30 days of calving. That is more than 1 in 12 cows calved. It is useful to analyse different lactation numbers as maiden heifers, which do not commonly receive internal teat sealants, can have problems with dry period infections.

Recurrence rate where mastitis recurs in the same quarter, e.g. back left quarter in January, March and April. If more than 10% of quarters recur there could be problems with Strep. uberis or Staph. aureus infections, or problems with mastitis treatment or detection.

Seasonality.There can be times when there are peaks of mastitis. This could be related to calving pattern, housing, weather conditions, management changes etc.

Housing.There can be differences in mastitis incidence between barns which might be due to the accommodation or the group of animals housed (e.g. lactation 1 compared to old cows) or stage of lactation (fresh or end of lactation cows).

Mastitis mortality. How many animals died and was this due to toxic or gangrenous mastitis?

Bacteriology is useful in confirming initial views of the likely cause of mastitis. Ideally bacteriology is carried out on all clinical cases. This data then can ensure that the correct control measures are being implemented. This data also can help with treatment protocols.

Bacteria can be linked to specific issues. For example; Pseudomonas is commonly associated with contaminated water supplies, Strep. uberis with straw bedding, Klebsiella with wood bedding products and yeast mastitis with poor intramammary infusion hygiene. There are some herds with very limited or no bacteriology results.

The advisor should have a good idea of the likely problems areas after reviewing mastitis data and bacteriology. An advisor will be at a significant disadvantage if the farm has poor mastitis records.

2. Review current mastitis management

It is advisable to have a standard approach to ensure that all aspects of mastitis management are investigated. The temptation might be to focus on the key areas identified from data analysis and discussions with management and then find later that there were other important areas were overlooked.

It is important to carry out a complete assessment of mastitis management covering all areas using a systematic approach. This author will check environment, milking routine, treatment, dry cow therapy, milking machine function etc.

This author likes to arrive about two hours before milking and sit down the owner and manager in an office and get them to talk about their mastitis problems and concerns. During this time the key points of mastitis will be discussed. Very often there is confusion between clinical and subclinical mastitis. It is important for them to understand the basics of mastitis, when infections enter the udder and the differences between the different bacteria.

Management are asked what they think has caused the problems, the changes that they have tried and how successful these have been. It is helpful to know details about the farm staff, their attitude, experience and limitations. Background information on mastitis management is collected at this meeting before the actual farm visit starts.

Then it’s time to put boots on for the farm visit where observations, tests and questions will be asked to staff. This part of the visit might is likely to take between three to four hours for a simple herd of 200 cows. For large dairies with multiple parlours and various teams of staff, the visit might take one to two days.

Photos and video recording can be useful for identifying problem areas and remembering what was seen. Photos can be powerful in highlighting problems in the report. Video recording the milking routine is helpful. A camera can be set up and left recording and reviewed later to see what happens when the milkers are on their own!

Various tests will be carried out and might include;

• Assessing teat preparation by wiping teat ends with white towel just before unit attachment
• Percent of teats covered with post dip
• Liner cleanliness and/or swabbing
• Teat scoring immediately after milking
• Scoring legs, teat and udder cleanliness
• Examining milk filters
• Milking machine testing. Some advisors might get a specialist to test the parlour
• Examination of on farm culturing if the farm has its own lab
• Bedding samples for bacterial assessment
• Etc.

A range of other observations will be made such as milking machine checks such as liner slip, under or overmilking etc. Milking routine. Walking around all the housing and areas where animals live. The maiden heifer environment and their calving facilities. Observing cows being dried off and mastitis treatments carried out is very useful etc. All aspects of mastitis management will be checked.

This author prefers to carry out parts of the farm visit on his own so that he can wander around and investigate fully and discuss problems with milkers and others without management present. Opinions and comments from the staff are welcomed. About half of the visit time will be spent in the parlour for smaller herds which might only have one or two cow barns.

During the visit a range of samples might be collected. Herds are encouraged to sample and test all cases of clinical mastitis. Bulk tank analysis of sample might be suggested, especially coliform counts which indicate levels of faecal contamination. Low levels indicate good teat preparation and parlour hygiene which will reduce mastitis risk.

Readers should refer to m2 article ‘Top tips to reduce environmental mastitis’ (Number 19. November 2017) which describe key aspects to control environmental mastitis.

3. Agree and implement a control plan

At the end of the visit this author will sit down with the manager and discuss the findings. Products used and work currently carried out that have no benefit to the herd are highlighted and it is suggested that these can be stopped or discarded. Farmers can be sold products or told to carry out additional tasks that have little benefit. They do this in the hope that they will help resolve the problem. This can save valuable time and money.

The key findings responsible are described and demonstrated as appropriate. If the freestalls are dirty, take them to see these. If there is a teat damage, go into the parlour and show damaged teats. This is very powerful. Explanation of how and why these are causing mastitis problems are given. It is important that management understand this so that they will make changes.

This author then asks management to suggest possible solutions. The aim is to get management to come up with the same solutions as the author. This means that management take ownership of these changes. The likelihood of change being implemented will be higher than telling a farmer to do A, B and C. By the end of the visit management will hopefully have come up with the correct solutions to the key problem areas with assistance of the author.

An action plan is agreed, and timescales are put in place. For herds with a two or three staff implementing a plan is straightforward. For larger herds this can be a more complex task; for example, a herd of 12,000 cows milked through four large rotary parlours four times a day with a pool of 110 milkers where there is a high staff turnover.

The importance of training cannot be overestimated. This could include milking routine, sterile milk sample collection, environmental management, administration of antibiotic dry cow therapy and internal teat sealants along with treatment protocols. Various surveys around the world show that farm staff all like to learn and understand why certain tasks are important and this makes them feel valued and part of the farm. Objections, misconceptions and questions can be dealt with at training sessions.

Training should be ongoing. It can be a mix of classroom and practical demonstrations. For example, describe how to dry off a cow, administer dry cow therapy and an internal teat sealant at a classroom session. Explain the key steps and what can go wrong. The trainer will demonstrate this procedure on real cows and then get each member of staff to dry off some cows to prove they can do this correctly.

Use of standard operating procedures (SOP) is important so that everyone knows what they should do and what is expected from them. This is very important in large herds with a lot of staff. The same milking routine, treatment protocols should be followed all the time. Training will be needed for many SOPs.

At the end of this process, the key mastitis management changes should be implements, SOPs drawn up and staff fully trained. A written report is produced to highlight the key points. This will include photos and key data. The report should be concise and clear and can be shared with all farm staff.

4. Monitor and review progress

Some advisors might leave management to carry on from here. Farms want a long-term solution; they are busy places with lots of challenges and issues to be resolved. It is important to stay involved until a long-term solution has been achieved and even then, many farms still want input into their mastitis management even if it just to reassure them that everything is
alright.

A phone call to the manager is made about seven to ten days after the first visit to check that the report has been received, to deal with any questions and to check on progress with the action plan.

A follow up visit date will be arranged for a month or two later. A request is made for monthly mastitis records to be sent over which are analysed and a summary sent back to the farm. Positive feedback is sent over if progress is being made then. Often a card or email addressed to the farm staff is greatly valued. If no progress has been made or if things are starting to get worse then another farm visit is arranged.

Persistency and diplomacy are often required for mastitis investigations. Farms are busy places and other areas must take priority and so some progress might be lost and that is why it is important to work with the farmer to achieve his goal.

Mastitis investigations can take a significant amount of time, but the long-term success is great, not only for owners but managers and staff. I remember being on a farm where the milkers were so happy as they had no cows under treatment for mastitis. Some herds have mastitis rates of 15, or 1% of the herd per month, and still want to get lower. High mastitis rates are no longer acceptable in today’s world of dairying.

Text and illustrations: Peter Edmondson, Udderwise Ltd.