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Dry cow therapy

Course: Transition Cow Management | Last Updates: 1st June 2017

 
Andrew Bradley
Clinical reader in Dairy Production Medicine and director of Quality Milk Management Services
Bristol University
Biography >>
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Drying off is the single biggest investment most farmers makes in udder health in a year and provides the best opportunity to cure existing infections and set a cow up for a productive subsequent lactation.

What is the dry period?

The dry period gives the cow a metabolic and physical rest from milking and may include the use of dry cow therapy (a long-acting intramammary antibiotic), with or without a teat sealant.

To ensure cows calve in with a healthy udder, cleanliness during the drying-off process and in the dry period itself are essential. Close attention to somatic cell count (SCC) and clinical mastitis records is also a must to monitor the success of a farm’s drying-off strategy, while also helping target management changes where necessary.

With increasing global pressure for farmers to implement responsible use of antibiotics, records are also a vital tool in helping producers and vets establish how selective dry cow therapy could be implemented.

Role of antibiotics in the drying off period

The dry period is the best opportunity in the lactation cycle to remove infection, with cure rates from intramammary antibiotic use much higher than during the milking period.

You can reasonably expect high SCC cure rates of at least 85% across all pathogens when environmental management is good.

At present, many dairy farmers will use dry cow therapy across all cows at drying-off. However, antibiotics use is increasingly scrutinised due to resistance issues. The main concerns are over preventative use.

Use of antibiotics on low somatic cell count (SCC), uninfected cows at drying-off is prophylactic and farmers need to think carefully about how to justify using them in such a way.

However, antibiotics should always be used where necessary and this is when close attention to records comes into play.

Reviewing drying-off strategy

Looking at records with a vet will give a good indication of how successful a farm’s dry cow management is and whether management improvements or savings in medicine use can be made.

It is essential to look at how good a farm is at preventing infection in the dry period and also examine cure rates. This is especially important considering a cow will give 5-15% less milk a quarter if it becomes infected in the dry period.

Cows that record an SCC of more than 200,000/ml within the first month after calving are likely to have been infected in the dry period.

This data can be referenced against records to see whether it is a new infection or a failed cure. What can confuse things is the fact a cow may have cured, but become reinfected during the dry period. That’s where good environmental management is important.

Key targets:

  • Less than 10% of animals should calve in with high SCC (including heifers).
  • Of cows that are dried off with a high SCC (>200,000 cells/ml), 85% should calve in with low SCC (cure rate).
  • Of cows that are dried off with a low SCC (<200,000 cells/ml), less than 10% should calve in with a high SCC (new infection).

Recording clinical mastitis incidence is also crucial and well worth the effort. Look at the number of cases in the first 30 days of calving as these infections are likely to have originated in the dry period. Less than one in 12 cows should get mastitis in this period. Two in 12 suggests a problem likely originating in the dry period. The DairyCo Mastitis Control Plan data shows probably 50% of herds have above one in 12 and 30% above two in 12 cases.

Culturing a proportion of high SCC animals and clinical mastitis cases from early lactation will provide an understanding of the causal pathogens. Attention can then be paid to prevention.

Targeted use of antibiotics

Good records are an important tool when considering targeting dry cow therapy at cows that need it. If records suggest a farm is good at preventing infection, further discussion should be had with a vet to establish if and how selective dry cow therapy could be used.

Targeted use is usually based around an SCC threshold, which will be farm specific and depend on the needs of the herd, performance and pathogens present.

In a lot of herds 200,000cells/ml is used as a cut-off. When a cow has recorded less than 200,000cells/ml in the last three milk recordings (before drying off) and she has had no clinical mastitis, she is unlikely to be infected and an antibiotic may not be necessary.

A teat sealant should then be used on every cow. Sealants have an important role to play in preventing infection in the dry period.

A natural keratin plug usually forms at the end of the teat after drying off, however not all cows develop this plug and it can take several days, even weeks for the plug to form in some cows, which leaves the udder exposed to infection.

A teat sealant provides an effective barrier, however it must be administered correctly. Antibiotic persistency can also vary and should be considered carefully depending on dry period length. This is also where sealants can help.

Drying-off technique

Whether using an antibiotic and sealant or sealant alone, cleanliness should be the primary focus at drying off. This is even more important when using a sealant on its own because if bacteria are pushed into a low SCC, uninfected quarter there is a significant risk of severe and even toxic mastitis.

If antibiotics are infused poorly, issues can still arise – though the consequences are less likely to be seen until the next lactation.

The drying-off process should always be a dedicated task and not take part during milking time or in an environment with a lot of dust and water. It is an important job and should not be rushed. Bring cows back into the parlour and then follow a step-by-step process:

  • Wear a clean pair of disposable gloves and ideally put a fresh pair of gloves on between cows.
  • Clean off any gross udder contamination and pre-dip/spray with a teat disinfectant, ensuring 20-30 seconds’ contact time.
  • Wipe teats dry starting with the teats furthest away from you (far to near). The main principle to follow is never to reach past a clean teat.
  • Scrub teats with surgical spirit and cotton wool, again starting with the teats furthest away from you (far to near).
  • Even if cows have just been milked, foremilk every quarter to remove any pathogens in the teat canal. Start with the teats closest to you (near to far).
  • Scrub teats again with surgical spirit and cotton wool, concentrating on the teat end, and ensuring cotton wool is visibly clean after the final scrub. Start with the teats furthest away (far to near).
  • When using dry cow therapy, infuse into the closest teats first (near to far) and massage up into the udder. Clean again with surgical spirit and then put in the sealant.
  • When using a sealant, always start with the teats closest to you to avoid contaminating clean teats. The sealant should sit in the teat canal and not be massaged up into the udder. To prevent this, grip across the top of the teat, insert the nozzle fully and put the sealant in.
  • Post-dip teats and let cows stand for half an hour on a scraped loafing yard. This will allow teats to close. Also avoid doing other jobs such as trimming tails or feet at the same time.

Environment in dry period

A cow is five to 10 times more susceptible to infection just after drying off and close to calving compared to when she is in milk, which means careful environmental management is crucial.

The basic principles of regular bedding and scraping, managing a dry, clean environment and avoiding poaching of ground and adopting fly control all apply. Also group dry cows away from the parlour to avoid the milking stimulus and don’t put fresh cows in the sick pen to avoid infection pressure.

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