19 December 2018



neil evans with farmers at sdct event

A switch from blanket antibiotic treatment at drying off to targeting only cows that need it has cut antibiotic use at a Welsh dairy farm by more than a third.

Drying off has traditionally involved using intramammary antibiotics across all cows to treat and prevent new infections developing during the dry period.

But many milk buyers are now setting new standards on the use of antibiotics in dry cows, including requiring farmers to put strategies in place for adopting selective dry cow therapy (SDCT).

Neil and Diane Evans, who run a high yielding flying herd of 180 Holstein Friesians on an all-year round calving system, had been tubing all cows at drying off with antibiotics until they trialled SDCT as part of a Farming Connect project.

“Antibiotics cover a multitude of sins, you know you are safe if the cow has had antibiotics at drying off, but the world moves on,’’ says Mr Evans, of Holebrook Farm, Wrexham.

Holebrook Farm is a Farming Connect Focus Site and, as such, a trial was put in place to study the effectiveness of SDCT in the herd.

Rhys Davies, Farming Connect Dairy Technical Officer for North Wales, who designed and oversaw the project, said Mr Evans had previously considered implementing SDCT but was nervous about taking the leap.

During the trial, which began in March 2018, Mr Evans was supported by his veterinary practice, LLM Farm Vets, to assess cell count records and to select cows suitable for SDCT.

“Full monthly recording data, together with accurate mastitis treatment records, are essential when reviewing Somatic Cell Counts (SCCs) during current and previous lactations,’’ Mr Davies explained.

To work out which treatment to apply to individual cows, clinical mastitis samples are collected from the cows and analysed at LLM’s laboratory. The results identify the mastitis-causing pathogens.

The farm’s vet Sarah Hampson, who led a Farming Connect workshop on SDCT at Holebrook Farm, says testing establishes which treatment approach is needed.

SDCT was ruled out in cows with a lactation average SCC of more than 100,000 cells/ml, or those that had a case of clinical mastitis in the latter stages of her lactation.

Mrs Hampson recommends a cautious approach to SDCT, especially when it is first implemented.

“It is selective for a reason. In cases where there have been disasters it has been when farmers have gone straight in without checking individual mastitis levels.’’

If in any doubt, use antibiotics, she adds. “If there is infection and you are only using sealant you will put a plug on the infection.

“SDCT should not be used in cows with staph aureus, until the cause has been addressed.’’

As milk buyers often require incremental reductions in antibiotic use, a cautious start is sensible if goals are to be achieved, she suggests.

For the trial at Holebrook Farm, every cow treated with dry cow antibiotic was also given a sealant and cows with low cell counts had a sealant only.

Teat end scoring was carried out on all cows at drying off - any animals with teat damage or warts were treated with both antibiotic and sealant regardless of SCC values.

Average infection rates in the next lactation show minimal difference in cell count between cows on sealant and those with antibiotics.

On average, of the cows given sealant alone, 76% experienced a cell count drop and 24% a cell count rise.

Of those administered antibiotic dry cow therapy, 72% had a cell count drop and 28% a cell count rise.

According to Mr Evans, the only freshly calved clinical case of mastitis treated was a cow that had been given dry cow antibiotics.

“As you would expect, the cows selected for antibiotic dry cow therapy had a significant drop in cell count and shows the value of treating udder issues in the dry cow period,’’ says Mrs Hampson.

Dry cow antibiotic tube use between March and August 2018 reduced by 39.5% - the equivalent of tubing 28 fewer cows with 112 dry cow tubes - compared to the same period in 2017.

For cows that averaged a low SCC during the lactation but spiked at 200,000 cells/ml or higher during a single recording, a new method of identifying subclinical mastitis in individual quarters was used.

QScout analysis pinpoints quarters with elevated cell types and cell type ratios; it enables accurate, quarter-level diagnosis which means only these need to be treated during lactation and at drying off.

The results are instant and highlight individual quarters with high cell count just prior to drying off, says Natalie Parker, a vet technician at LLM, who carried out the testing and the weekly drying off of cows throughout the trial  at Holebrook Farm.

“As a precaution, all four quarters were treated with a dry cow tube and sealant during the trial but the aim in future is to only tube and seal offending quarters with both treatments,” she adds.

Record keeping of treated cows, especially of infected quarters, is key to establishing if there is a pattern, Mrs Parker advises.

Good advice and support from a vet is key to successful SDCT, says Mr Evans. “The training side of it is important, to make sure you are doing it properly and selectively.

“The benefit of the project is that it has been done properly by the LLM VetTech service. The protocols are really important.’’

SDCT is now part of his drying off protocols. “We will continue to have some level of input from our vet practice, it is an investment worth making for peace of mind,’’ Mr Evans suggests.

In Wales, Farming Connect is running a series of workshops in conjunction with local vet practices, on appropriate antibiotic use, keep an eye out for these on our events page.

Rhys Davies encouraged farmers to attend.

“These will consider the practical steps farmers and vets can take to demonstrate more responsible use of antibiotics,’’ he says.





Meticulous cleanliness is crucial at drying off as it is commonplace for infection to be introduced at this stage.

Not administering teat sealant hygienically risks a mastitis breakdown, warns Mrs Parker.

“If you lose a cow after SDCT it is usually because you have introduced infection at this point,’’ she says.

“Sealants are not cheap but if you get a speck of dirt on the tube, for instance if a cow kicks out and it touches her leg, don’t use it change it for a new one . You must consider the value of the cow compared to the value of that tube.’’

Not only should cows be as clean as possible, but the treatment area and the person must be clean and dry too.

Additional labour is useful, and the job shouldn’t be rushed, advises Mrs Parker. “Don’t dry off on a day when you have to rush, the last cows to be treated are as important and valuable as the first.’’

To start the process, pre-dip cows and wipe with an individual anesthetic, working from the teats furthest away to closest.

Individually wipe teat ends with cotton wool soaked in surgical spirit, nearest teat first; once one teat is wiped, tube and work from the closest teat to furthest away.

For cows identified as needing sealant only, administer sealant utilising the correct infusion technique, taking care not to massage into the udder by holding the top of the teat.

Administer antibiotic tubes to cows identified as needing treatment followed by sealant.

Dip all teats.

Apply tape to the tails of treated cows to ensure easy identification at calving.

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