Extremely wet conditions are associated with higher rates of mastitis in dairy cows. This is because the udder’s natural defences against bacterial invasion can be overwhelmed by the muddy environment. Preventing mastitis hinges on maintaining the balance in favor of the cow’s natural defences over the number of bacteria looking to invade the teat canal.
The presence of mud and manure in the environment favors the growth of environmental bacteria, such as coliforms, that can cause mastitis. In addition, moisture and mud on the teat skin interferes with the protective coating of fatty acids that are normally present on the healthy udder and teat.
This leads to the skin of the udder and teat becoming dry and more prone to small cracks. These cracks harbor bacteria which multiply and can enter the teat canal causing mastitis.
Preventing Mastitis with Teat Sanitisers
Teat sanitisers (dips and sprays) are designed to protect and disinfect teat skin. Spraying or dipping the teats after each milking with a registered teat disinfectant (with emollient) at the correct concentration is the best way to protect udder health. Good coverage of the entire barrel of all four teats – with a droplet of sanitiser hanging from the end of the teat – is important for post milking disinfection to be effective.
After milking the teat canal remains a little open for about 20 minutes. Standing the cows quietly for a short period after milking can ensure that the teat canal is closed before they are again exposed to mud.
Pre-milking teat disinfection (sanitiser applied prior to attachment of the milking machine) is an effective way of decreasing mastitis due to environmental bacteria. Pre-milking products (dip or spray) are not the same as post-milking products and must be labelled and registered as suitable for pre-milking use.
The label directions should be followed and the following tips may help:
- Excessive dirt and faeces will deactivate the disinfectant and must be removed prior to pre dipping. Fore-stripping or wiping the teats with a dry paper towel helps to remove dirt.
- The teats must be dry prior to application to ensure the disinfectant is not diluted.
- The disinfectant must remain on the teat for 15 – 30 seconds.
- Pre-dip must be removed, with a single use wipe or paper towel, before the clusters are applied to prevent residue issues.
- The use of pre-dip does not remove the need for post milking teat disinfection as they perform different functions.
Tackling Clinical Cases
During wet conditions the milking staff need to be on the alert for clinical cases at milking, particularly around calving. All cows in the colostrum herd should be hand stripped prior to milking, with treatment being warranted if clots or abnormal milk remains after 3 squirts.
Finding individual cases in the main herd can be a challenge if clots are seen on the filter sock. The milkers may have to resort to fore stripping the quarters of suspect cows. Suspect cows include those with swollen udders, udders that have not milked out properly, those treated for mastitis in the last 2 months or those cows that have a history of a high individual cell count (above 250,000). It is reasonable to consider daily foremilk stripping for the whole herd at high risk times, but the use of gloves and attention to hygiene is important to avoid causing further spread.
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Treatments are much more effective if given early in the course of disease. Antibiotics should be based on culture results and will need to be discussed with your vet. Some general tips that can help during wet conditions:
- Take a milk sample in a sterile tube from each clinical case and keep it in the fridge or freezer before antibiotics are used. The sample can be sent off for culture if the case does not respond to treatment or if an outbreak requires further investigation.
- In muddy conditions the teat ends must be thoroughly cleaned and disinfected prior to administering intra-mammary antibiotics as the chances of introducing nasty bacteria are particularly high. Take care not to insert the tip of the tube further than a few millimeters into the teat opening.
- Treat clinical cases as usual – milk them out fully then give them a full course of antibiotics.
- Known clinical cases should be milked last to prevent unnecessary cow to cow spread during milking.
- Gloves should be worn during milking and when handling clinical cases.
- Remember that treating during lactation does not ‘complete’ the cure. All cows that have had a clinical case of mastitis or a cell count above 250,000 should receive a dry cow intra-mammary at the end of lactation (see below).
When to Call your Veterinarian
Producers need to work closely with their veterinarian to effectively treat mastitis in their herd, particularly if tackling an outbreak during wet weather. The following indicators may be useful in determining if it is time to contact your veterinarian:
- Clinical cases are not responding to the antibiotic chosen – i.e. a second course of treatment is required by more than 4 out of 10 clinical cases.
- You have more than 3 clinical cases per 100 cows in a month (or 5 per 100 cows in first month of lactation).
- Large numbers of cows have individual cell counts above 250,000.
- BMCC consistently above 300,000.
- BMCC fails to lower after 10 - 14 days. It is normal during extreme wet weather for the number of mastitis cases and the BMCC to rise, however it should begin to drop if the treatment and preventative strategies are effective.
Longer Term Recovery from Mastitis
Treating clinical mastitis with antibiotics usually cures the symptoms but may not completely rid the quarter of the infection. These subclinical cases need to be tackled at drying off. Following wet conditions it is worth discussing whole herd blanket dry cow therapy with your veterinarian.
Sometimes different products are recommended for different cows based on their history.
Once a day (OAD) milking
Changing the frequency of milking for at least part of the herd is a common strategy to combat wet conditions. A summary of the main impacts of milking once a day are given below:
- Production declines between 10 and 43% are likely, with the larger losses being seen if OAD milking is instituted early in lactation. This effect is more marked in Holsteins.
- Losses in body condition and reproductive performance in early lactation may be minimized by milking OAD, but it comes at cost to production. Cow production will increase if twice daily milking is recommenced. Production losses are minimal if recommenced within 10-14 days.
- Dry matter intakes decrease marginally with OAD milking over the medium term, but this is unlikely to be particularly helpful to address a sudden feed shortage. Be aware that the opportunity to feed concentrates at the dairy during milking will be halved with OAD milking.
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Dairy Welfare
We Care Managing milking in wet conditions
- BMCC rises but this is not associated with more clinical cases of mastitis. The rise in BMCC is most marked in the first few weeks following the change to OAD milking and may cause problems with meeting premium milk quality grades, particularly in late lactation.
- The composition of milk is slightly different with higher percentages of milk fat and protein. The protein shows a higher proportion of whey.
- Overall the herds in NZ undertaking OAD milking had cows in better body condition and had higher reproductive performance as a result. They used 11% fewer CIDs and conceived on average 3 days earlier.
- It is wise to discuss a change to OAD with your veterinarian or dairy adviser.
Emergency Milking
In extreme weather conditions it may not be possible to milk for short periods. Generally, as long as milking begins at least once daily, within 3 to 4 days then milk production will recover. Cows close to dry off face the greatest risk of drying off. Cell counts will initially be high but will also improve over a few milkings.
Summary
- Concentrate on teat disinfection and hygiene at milking to minimize mastitis.
- Identify and treat all clinical cases early.
- Consider pre-milking teat disinfection in very muddy wet conditions.
- Once a day milking may be a viable short-term solution during wet conditions.
Further Resources
If you require any professional advice on mastitis please contact your veterinarian or Countdown
Downunder adviser. Additional information about milking in wet conditions can be found in the references
listed below.
Teat disinfection issues (pre and post milking):
USA extension network – Questions and answers about pre-dipping (US perspective). Available at
www.extension.org
Countdown Downunder FAQ Sheet: When should pre-milking teat disinfection be considered? Available
from technical advisers listed at www.countdown.org.au
Countdown Downunder Technote 7. Use post-milking teat disinfection – spray or dip every teat at every
milking. Available at www.countdown.org.au
OAD milking:
CowTime QuickNote 1.4 Once a day milking. Available at www.cowtime.com.au
Emergency milking:
Alternative milking arrangement during black-outs. Available at www.dairyaustralia.com.au
For further information, please visit: www.dairyaustralia/Managing-In-Wet-Conditions
Dairy Australia
Level 5, IBM Centre, 60 City Rd
Southbank Victoria 3006 Australia
