A recent survey by Farmers Weekly revealed almost a third of dairy farmers are concerned about selective antibiotic use at drying off. However, as one Dorset farmer has found, targeting antibiotics towards cows that need it can help cut costs and reduce chronic cell counts.
Global pressure for farmers to use antibiotics responsibly may be the headline reason to tackle their use on farm, but targeted use could also bring big cost and herd management benefits.
Blanket use of antibiotics at drying-off is one area the industry is increasingly being challenged to address and is one herd manager Richard Anning decided to tackle head on.
“We wanted to jump in first as we knew more buyers want reduced antibiotics use and we wanted to try to reduce use where we could,” he explains.
As a result, last year Mr Anning and Velcourt assistant farm manager Will Betts in consultation with their vet, Mike Kerby, of Delaware Vets, decided to just use a teat sealant at drying off on low cell count cows at Evershot Farms’ Melbury Dairy.
By doing so they have been able to direct cost savings towards treating cows with chronic high somatic cell counts (SCCs) in the 440-head herd. Consequently, in just 12 months the number of chronic SCC cases has reduced from 23-27% to 16% and Staph aureus has virtually been eliminated.
Melbury Dairy improvements
- 80% Cure rate of chronic high SCC cows in dry period
- 90% go into dry period low and come out low (three-month rolling) versus 67% a year ago
- 160,000 is the bulk milk cell count, down from 200,000 cells/ml to
- 16% chronics cow – was 23-27%
Evershot Farms runs three herds totalling 1,000 cows, with all cows managed on a 56-day dry period at Melbury Dairy.
With the view to rolling the concept out to all dairies, the decision was made to trial the concept at Melbury.
Low mastitis rates of 23-27 cases for every 100 cows, coupled with good record-keeping meant the unit was geared up to tackle the issue.
Following discussions with Mr Kerby and close examination of individual cow data, cows with average SCC readings of 150,000 cells/ml, no mastitis and no readings of more than 200,000 cells/ml in the past three milk recordings were chosen to just receive a sealant at drying off.
Cows with a 200,000-400,000 average cell count receive an antibiotics tube and sealant.
Mr Anning says careful drying-off protocol has been vital since moving to the sealant only approach.
“Cleanliness is crucial as you don’t want to put any more bacteria in there, as once it is sealed, it is not coming out. I learned a lesson as the first cow died of E coli,” explains Mr Anning.
Mr Kerby agrees: “If you are dirty and you use an antibiotic, it might save your bacon, but if you use a sealant only, you could get a nasty shock. You need to use the sealant properly and put it in the teat and not massage it up into the udder,” he says.
At drying off, cows are dipped with methylated spirit after milking and wiped with cotton wool. Teats are cleaned from front to back of the udder and sealant is infused working back to front.
Gloves are worn at all times. Far-off drys are at grass from April to October and housed on green-bedded cubicles in the winter. Transition cows then move on to a loose-bedded straw yard.
Management has always been geared towards preventing a build-up of chronic SCC animals, which could infect others and increase bulk SCC levels.
This is achieved through automated cluster flushing, some culling, good ventilation and milking routine and maintaining dry beds. A high stocking rate during the dry period means attention to every aspect is particularly important.
However, the herd had always struggled with bulk milk tank cell counts “grumbling” at about 200,000/ml, leaving them exposed to milk price penalties, says Mr Kerby.
“Several times, bulk SCC went over the threshold by a small amount – it was too close for comfort. We wanted to get a 150,000 cells/ml rolling average,” he explains.
These higher-than-desirable cell counts were largely due to a number of chronic high-SCC, Staph aureus-carrier cows.
Attempts to cure these animals during lactation had proved unsuccessful, so the decision was made to partition cost savings from targeted dry cow therapy to treat these animals in the dry period, which generally yields better results.
Now, cows with an average SCC of more than 400,000/ml will have their milk sampled to identify the pathogen.
They will then receive an appropriate injectable antibiotic at drying off, together with an intramammary tube and sealant.
Mr Anning says the results have been marked. “It’s worked brilliantly as it has been targeted. Last year we were doing a lot of milk samples and we had a lot of Staph aureus, but now we are doing hardly any [sampling] and it is now more C. bovis, which is easier to treat,” he says.
The farm is now achieving cure rates of 80% for chronic cows in the dry period, the number of chronics has fallen significantly and bulk milk SCC has dropped 20% (see “Improvements” left).
The team also takes a similar targeted approach to treating clinical mastitis and test milk from infected quarters regularly. This allows antibiotics tubes to be selected based on the causal pathogen.
This helps achieve better cure rates, meaning cows are less likely to have chronic high cell counts.
As the pool of chronic SCC cows has reduced, the number just receiving teat sealant at drying off has increased to 40-50%.
Considering the additional cost of testing and injectable antibiotics, overall costs have subsequently reduced by about £350, with savings set to increase further as chronic cases continue to drop.
Further SCC reduction
Mr Anning says it took nine months for the effects to become apparent, but the benefits have made him want to push bulk SCC down further.
“We have reduced staph carriers with a combination of culling, specific treatments and cluster flushing to prevent spread,” says Mr Anning, who says he has not had to cull for SCC recently.
“Now we have fewer cows to sample, I want to target cows with SCC of more than 200,000/ml for targeted treatment.”
Mr Betts believes monthly team meetings and making herd data available on a practical basis is crucial to the success of the strategy and has been convinced this approach should be rolled out to the farm’s 350-cow herd at Golden Cross.
“It is beneficial to our costs and focuses us on specific issues. It also benefits cow health and welfare by allowing more attention to detail on an individual cow basis which will mean cows will last longer and be more productive,” he says
Mr Kerby says all farmers could benefit from thinking about how they use antibiotics at drying off.
“Don’t shy away from it, even if other aspect aren’t perfect. Attention to detail, use of records, bacterial sampling and primarily scrupulous drying-off procedure is key to success.”
Mr Kerby encourages farmers to work with their individual farm vet to implement a specific programme that works for the farm and herd.
The dry period represents the biggest opportunity for farmers to make an improvement in udder health and set a cow up for a productive subsequent lactation.
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