Udder Health
Written with help from Steve Cranefield, Mastitis Specialist
The ultimate aim of mastitis control is to limit the number of bacteria on the cow’s teats and to reduce the risk of bacteria entering the udder through the teat canal. Although this sounds simple, mastitis is the end result of complex interactions between the cow, bacteria, environment, milking machine and the farmer. The relative importance of these factors varies from farm to farm so it is important that your plan is specific to your farm.
There are two key elements to reducing mastitis
One - eliminate existing infections
Infected cows are the source of infection for other cows during lactation.
Cull long term infected cows:- We need to make more use of historic records to identify and cull chronically infected cows. Too often clinical mastitis records are incomplete and/or poor use is made of historic herd test information so it is only the recent high SCC cows that are culled. Also, mandatory culls (e.g. a high empty rate) often take precedence over culling for mastitis.
Drying off strategies:- We should all aim to achieve consistently low SCC throughout the season to reduce the need for antibiotic dry cow therapy at dry-off. Cows with an ISCC of <150,000 cells/ml and heifers with a ISCC of < 120,000 cells/ml can be regarded as uninfected and new infection can be prevented with teat sealants although strict hygiene is critical when these are administered.
Two - prevent new infections
There are 3 key areas of importance during milking that will reduce the mastitis risk:
A. Identify and treat mastitis cows early
Routine stripping of the herd (e.g. a quarter at every milking) will identify infected cows quicker to minimise the spread of infection.
B. Ensure your cows have good teat skin condition all year round
Teat spraying is still the most important single thing you can do to reduce the spread of mastitis. The reason for this is that every time you apply cups to a cow you are passing bacteria to the teats of the next cow to be milked. These bacteria can then enter the teat canal and cause mastitis
Bacteria from milking an infected cow will contaminate the cluster for the next five cows that are milked by that cluster. Teat spray trials in New Zealand and overseas all show a 50% reduction in the new infection rate if teat spray is mixed and applied correctly. Healthy teat skin has a fatty acid layer that slows bacterial growth reducing the mastitis risk. If teat skin is dry the fatty acid layer is lost and bacteria will multiply in the cracked skin. It is critical to achieve good teat condition in your herd all year round. This requires addition of sufficient emollient and ensuring full coverage of all teat surfaces at every milking all season. This should be a key focus and constantly assessed throughout the season. Pre-milking teat spraying the colostrum cows will assist to improve milk let down, improve teat condition and reduce bacteria on the teats.
C. Adopt efficient milking routines to minimise teat end damage
All bacteria that cause mastitis have to enter through the teat canal. Having a normal intact teat end is the best defense against entry of mastitis bacteria. The teat skin should be smooth and supple and the teat canal should just be visible as a pin point hole about 1mm in diameter.
Teat ends can be damaged from the physical action of the milking machine allowing bacteria to grow and enter the teat canal. Teats may be examined and classified as normal, rough or very rough / cracked.
Adopting efficient milking routines will help reduce the mastitis risk from teat end damage caused by over-milking.
MaxT (maximum milking time) is a strategy which defers residual milk to the next milking, where it can be harvested more efficiently. Cows are milked to a pre-determined end-point — either to a fixed time point, or to a set milk flow rate threshold, whichever comes first.
Cows will tell you they have mastitis!
If you assess your cow’s teats once a month you can learn why there is mastitis in the herd and monitor the results of change. Farmers are encouraged to assess 50 cows for teat skin condition and teat end damage once a month through the season as an early indicator of problems. The targets are:
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Teat skin condition - target > 95% supple.
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Teat end damage - target > 90% normal.
If any of these risk factors are lower than the target then farmers should look for rectify possible causes or seek expert advice to avoid mastitis.
Get in touch with the Teatwand team for more information and to connect with Steve our expert.