24 April 2025
A project involving multiple Welsh dairy farms has demonstrated why collecting data to establish the mastitis red flags specific to an individual herd can be key to reducing disease incidence.
Farming Connect enlisted ten herds ranging in scale across mid, south and west Wales to work with veterinary consultant James Breen to research the value of using data to establish mastitis and cell count (SCC) patterns and their causes.
James supported each farm with expert advice on how to reduce their incidence of clinical and sub-clinical mastitis.
Industry reports generally put the mastitis incidence in UK herds at an average of 30-35 cases per 100 cows.
Farm consultant Anna Bowen, of The Andersons Centre, calculates that in a 150-cow herd this equates to between 23-53 cases a year.
At an estimated cost of £314 for each case of clinical mastitis, the figure used in the 2024 Kingshay Dairy Costings Report, the annual financial loss to that herd would be £7,222 - £16,642.
“While achieving zero incidence of mastitis is unrealistic, there are significant financial benefits to reducing incidence, plus the welfare benefits, positives for public perception of agriculture, and the potential knock-on impacts of reducing antimicrobial usage,’’ says Anna.
The project farms supplied James with SCC and clinical mastitis data but this varied in quality and source according to the frequency of milk recording and on other factors such as whether all clinical cases were recorded.
Using this information, James ran a mastitis pattern tool for each herd to establish the predominant mastitis pattern in the last quarter, and the current, quarterly, and rolling 12-month incidence rates of clinical mastitis.
Further information on cure rates, dry period new infection rates, and incidence rates in heifers could also be calculated where the data supported it.
At every data collection stage, the farmers were made aware of where the dry period and lactation cases had originated, and the infection rates in their heifers.
Crucial to the project was sampling the milk from cows with clinical mastitis to establish the bacteria responsible for the infection.
The most common mastitis pathogen was S.uberis, followed by E.coli. Seven samples grew Aerococcus viridans, a Gram-positive bacterium of increasing importance.
The farmers had been advised how to take aseptic samples. Anna, who collated the project findings, said the process had highlighted how important it was that sampling was done in a hygienic way.
“Of the 53 samples submitted, nearly a quarter were contaminated and so were effectively wasted samples,’’ she said. “This usually happens due to poor collection technique.’’
Sampling is important because knowing the mastitis-causing pathogens on a farm means appropriate treatments can be used, she added.
The data showed that none of the farms had contagious mastitis – all showed an environmental pattern either originating in the dry period or during lactation.
The incidence of mastitis ranged from one farm with two cases per 100 cows in the spring to another with 104 cases per 100 cows in winter.
Anna says some of the differences were down to improved recording while others reflected the farm’s disease pattern.
Among the interventions recommended to specific farms by James were: housing, bedding, and the milking routine, with ventilation, manure management and stocking rates also key areas for attention.
One farm with an environmental mastitis pattern was advised to open up the ends of a shed to improve air and cow flow and increase the loafing area.
More frequent scraping was recommended together with repairs to prevent slurry from pooling and a reduction in the stocking rate among the high lactation group.
For another farm where mastitis originated in the dry period, James advised more frequent moves of dry cows at grass.
The stocking rate in the farm’s dry cow shed was too high and ventilation was insufficient therefore the farmer was advised to open up the roof ridge to improve ventilation and to bed down more frequently.
Another suggestion was to consider the use of portable cubicles to reduce the stocking rate.
Anna said mastitis incidence on some of the farms had reduced during the 12-month project but on others it had actually increased.
She pointed out that many mastitis issues take “considerable effort’’ to resolve and that time is also a factor.
“It may, for example, need a year to pass so that winter housing can be assessed, changed, and the cows can then pass through the housed period before data is available,’’ she said.
The farms that saw the most positive results were those who worked with their vets to reduce incidence.
In terms of SCC, one farm managed to reduce its rolling SCC from 310,000 cells/ml to 262,000.
Anna said SCCs had been a challenge for the farm and a reason why it had joined the project.
Putting a financial value on SCCs is difficult as it depends on the levels penalties and bonuses are imposed in individual milk contracts, and the value of those, she added.
“One of the farms has penalties imposed at a fairly low SCC, and produces a large volume of milk therefore an extra 0.5 pence per litre (ppl) is a significant sum of money and would quickly pay for the changes recommended by James,’’ said Anna.
“In contrast another has no penalties or bonuses until SCCs are exceptionally high, and is a very small herd so 0.5ppl is a much smaller sum of money. However, in a small herd there is less dilution, so stopping one cow having a high SCC or curing her during the dry period may have a big impact on the herd’s overall bulk milk SCC.’’