On-farm bacteriology can play a big role in driving down antibiotic use further and faster. Dairy Farmer reports.
Despite considerable progress being made to reduce the incidence of mastitis and the use of antimicrobials to treat infections, mastitis still represents a drain on dairy businesses. This means there is also the opportunity to reduce infections further to reduce costs and increase efficiency.
The 2022 Kingshay Dairy Costing report showed the average incidence of clinical cases at 30 cases per 100 cows, down from 39 in 2019, a reduction of 23%. The top 25% of farms recorded 16 cases per 100 cows.
This is significant progress that farmers can be rightly proud of, says dairy vet Matthew Dobbs, chief executive of Agsenze, the UK distributors of the Mastatest system.
Cases had been stubbornly holding at about 40 per 100 cows for many years, so things are moving in the right direction. However, it is important to keep striving to reduce cases further as clinical mastitis is still costing the average farm more than 10,000 per year and accounts for 9% of all culls.
Kingshay also reports a significant reduction in the use of antibiotics on dairy farms, particularly the antibiotics critically important to human health. However, in the past two years, the rate of the decline has plateaued.
Mr Dobbs says: If further progress is going to be made in both reducing the incidence and cost of clinical mastitis and further cutting the use of antibiotics on-farm, then new technologies which increase the precision of diagnosis and treatment will play an increasingly important role.
The objectives should be to reduce the cases of mastitis while also reducing the number of cases which are treated with antibiotics, which is where on-farm bacteriology will help better decisions to be made.
There is no universally effective intra-mammary antibiotic, with the effectiveness depending on the class of bacteria causing the infection. Bacteria can be classified into gram-negative and gram-positive strains, which respond differently to antibiotic treatments.
Mr Dobbs says up to 50% of mastitis on UK dairy farms is either caused by gram-negative bacteria, such as E. coli, or does not have an identified bacterial cause.
Treating these mastitis cases with antibiotics may be unnecessary as they typically resolve without any intervention, yet in many cases antibiotics are used as routine for no benefit.
For cows with a gram-positive mastitis infection, such as Strep. uberis or Staph. aureus, knowing the antibiotic the particular strain is most sensitive to will improve cure rates as the farms vet can make a better-informed decision about the most effective antibiotic to use.
Mr Dobbs says: If bacteriology is not carried out, it is difficult to refine treatment protocols. Where bacteriology has been used in the past, it has been a time-consuming process, requiring samples to be sent away for testing, with results often back on-farm too late.
The simple Mastatest on-farm system overcomes these drawbacks, allowing a sample to be tested with data back on-farm and simultaneously sent to the vet in less than 24 hours for prompt and accurate treatment decisions.
The test automatically processes milk samples using a simple cartridge system and an electronic eye which takes images of the samples as time passes.
The images are sent to the Cloud, where they are analysed and interpreted, with results in the farmer and vets inbox within 24 hours.
The results include the bacterial species present or confirmation of no bacteria being present and its sensitivity to common antibiotics. These data are used to generate and report a recommended treatment plan, based on a protocol devised by the farms vet.
Mr Dobbs says: Farmers and vets have timely data available to determine if antibiotics should be used and from the sensitivity profile, which antibiotic will be most effective.
This will allow more robust treatments and help drive down unnecessary use of antibiotics, reducing the amount of milk withheld and discarded.
The system can also be used to make better decisions about selective dry cow therapy.
