Mastitis is a common disease on dairy farms. From a disease perspective, mastitis has the second largest economic impact to dairy farmers.
Mastitis is the inflammation of the mammary gland (udder). The most common cause is a bacterial infection, although trauma can also be involved.
Mastitis develops from microorganisms invading the udder through the teat canal. They migrate up the teat canal and colonise the secretory cells. The colonised organisms produce toxic substances harmful to the milk producing cells.
Historically, the most common way mastitis spread was between cows through the milking process, known as 'contagious mastitis'. The most common way to spread it now is the 'environment mastitis' from housing and environment.
In the UK the average cost per mastitis case is £250-£300. More severe cases can result in much higher costs such as E-coli infections.
Milking Routine
The aim is to remove milk efficiently from the cow with minimal risk to udder health. The routine must be practical and labour efficient with the milker understanding the scientific reasoning for each step in the process to achieve this aim. Routine must include practices that limit the spread of contagious mastitis in the parlour.
Ideal Milking Routine...
Foremilk cows
Dry wipe clean teats
Wash and dry dirty teats
Pre-dip, allowing a 30 second contact time and wipe off
Attach the milking unit within one minute of teat preparation
Check machine sits squarely on the udder
When milked out, shut off vacuum and remove cluster
Teat dip once cluster is removed
Cows to remain standing for 30 minutes
Why Foremilk?
Early detection of mastitis
Stimulates the milk let down reflex
Removes bacteria that may have entered the teat canal since the last milking
Teat Preparation
Goal is for clean dry teats
Dry wipe clean teats
Wash and dry dirty teats
Avoid communal udder cloth
Predipping is the gold standard
If water is used to wash teats it should be sanitised as contaminated water can be a source of Pseudomonas and Nocardia mastitis infections.
Ensure only teats are washed and not the udder. When the udder gets wet, water drains back down onto the teats after they have been dried (magic water).
This increases the risk of liner slip and if sucked in through the top of the liner can contaminate milk or create impact forces which will increase the risk of new environmental infections.
Disinfection with 60ppm Iodine or 200ppm sodium hypochlorite is beneficial. In no circumstances should a communal udder cloth be used as this spreads infection from cow to cow.
Disinfectant in water for washing and dried with paper towels will keep total bacteria count lower than washing alone.
Milkers Hands
Milkers hands can spread mastitis bacteria from cow to cow. Hands cannot be disinfected so it is advisable to wear gloves.
50% of milkers hands infected before milking
100% of hands infected during milking
Gloves reduce the risk of transferring infection
Gloves must be rinsed throughout milking
Predipping
Disinfects the teat
Reducing the number of bacteria in bulk milk
Reduces the incidence of environmental mastitis
Minimum contact of 20-30 seconds is allowed
Thoroughly wipe off the teat before the milking unit is applied to avoid any chemical contamination of milk
Mastitis Detection
Foremilking
Change in the behaviour of the cow
Palpation of the udder
Observation of quarter swelling
In-line mastitis detectors
Checking the milk sock or filter at the end of milking
Udder examination is one way to check for subclinical mastitis cases.
Palpation of the udder
Palpate the udder immediately after milking when it is soft
Skin
Grasp the skin between the thumb and forefinger - it should be pliable and easily separated from the underlying tissue. If not, it suggests there is an oedema of the udder associated with infection or recent calving.
Udder Tissue
Palpate each quarter with both hands, one either side of the quarter. The udder should have a fine grain feel, if there are lumps, coarse grain or hard udder then it suggests a sub-clinical case.
Lymph Nodes
The mammary lymph nodes lie in-between the hind quarter known as the perineal region. Normally the lymph nodes are inapparent but will enlarge and feel nodular when infected.
In all cases of clinical mastitis, it is advisable to collect sterile pre-treatment milk samples for bacterial identification. This will allow the identification of pathogens causing clinical mastitis so that specific control measures can be implemented. It is preferable to process fresh samples, but they can be stored in the fridge for up to 5 days or frozen before going to the lab.
Mastitis Cows
Ideally, mastitis cows should be milked last to avoid the risk of residues entering bulk supply and eliminating any spread of infection. Often there are no facilities to separate, so if milked during the milking process, they should be milked into a dump bucket or dump line. Cluster used for dump line should be disinfected between use.
Post Milking
Post milking teat disinfection:
Kills bacteria on teat after milking
Reduces new infection rate
Allows for inadequacy in the milking routine
Improves teat skin condition
No effect on existing udder infections
Must be carried out after every milking
Dipping - fully immerse in the solution using 10ml per cow per milking
Spraying - need 2 rotations around the udder, one clockwise and the other anti-clockwise, 15ml solution used.
Automatic teat spray systems - can be unreliable and provide poor coverage of the teat and use high volumes of teat dip.
Milking Order
Preferable milking order:
Fresh calvers
High yielders
Medium yielders
Low yielders
High cell count cows
Mastitis and other treated cows
Bactoscan
Bactoscan and Total Bacteria Count (TBC):
Bactoscan is more accurate and faster, with results 3-4 times higher than the TBC Psychrotrophs are bacteria which grows under refrigerated conditions and are picked up by Bactoscan but not TBC. These are dust organisms and can be associated with poor or damp bedding.
Sources of bacteria in milk are: mastitis organisms from the udder, environmental contamination and dirty milking plant.
Environmental contamination can be measured with the Coliform count, >20/ml requires better udder preparation.
Milking Equipment
If not washed and disinfected correctly, milk films may build up inside the system. This allows thermoduric bacteria to multiply. These bacteria withstand pasteurisation, i.e. temperatures over 63°C. Levels over 175/ml suggest a wash-out problem.
If you would like more advise or are worried about mastitis within your herd, contact your DN Sales Specialist for more information.
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