Keeping bacteria at bay during lactation

Cows are at risk of new infections from contagious or environmental bacteria at every milking during this time.

An effective mastitis prevention programme will ensure more milk in the vat, less risk of milk penalties, less use of antibiotics and more time saved.

Bacteria in milk from infected quarters may contaminate the skin of many other teats during milking.

For example, after a liner has milked an infected quarter, bacteria may be transferred to the next 5-6 cows milked with that cup. After milking, bacteria multiply on the teat skin and may extend into the teat canal.

If the whole surface of each teat is disinfected immediately after milking, this spread can be minimised. Teat disinfection also helps to keep teat skin supple and healthy. Teat disinfection after milking reduces new infections due to cowassociated bacteria such as Staph. aureus by 50% and is also important in reducing Strep. uberis infections. It is one of the most effective cell count and mastitis control measures available, but it only works if it is done thoroughly.

Teat disinfectants must be diluted to the correct concentration for use. The active ingredients often lose their disinfectant ability with time after mixing, and if you include additives to improve skin condition (emollients) these may reduce disinfectant activity.

Any contamination with milk and other organic material also reduces activity. Correct mixing each day is best to get maximum performance. Some emollients are not suitable for use with particular disinfectants. Failure to cover the whole teat of every cow at every milking and poorly diluted teat sprays are the most common errors in teat disinfection.

Milking machines

Milking machine equipment has been designed to harvest milk efficiently and maintain healthy teats. Teats are attached to milking machines for 50-100 hours per lactation. Machines that are not functioning correctly can contribute to new mastitis infections by:

- Spreading bacteria from teat to teat and from cow to cow

- Damaging the teat ends and natural defence mechanisms of the teat canal

- Causing impact of bacteria-laden droplets into the teat canal, especially towards the end of milking

- Reducing the degree or frequency of full udder milk-out

The most common reason for milking machine problems is inadequate routine maintenance of mechanical components and rubberware.

A series of regular, systematic checks gives a simple method of finding problems and guiding preventative maintenance. If more than one person milks in your dairy, it is important to assign these checks to particular people, and ensure that the right person is alerted to any problems that are found or suspected.

Daily and weekly checks should be conducted by milking staff as part of their regular list of responsibilities.

Monthly checks should be done by the herd owner or manager or other skilled observer. Recording the results of monthly checks enables subtle changes due to wear and age to be detected more easily.

Bacteria are present in milk from all infected quarters.

They are spread to other quarters and cows by splashes or aerosols of milk that occur during stripping, by milkers’ hands, teatcup liners and by cross flow of milk between teatcups. Keeping hands and the milking area under the cows as free as possible from dirt and contaminated milk will help to reduce the risk of transferring bacteria from cow to cow.

Low pressure, high volume washing water should be used to sluice away manure. High pressure hoses should not be used directly beneath or around cows, as these can create aerosols of bacteria-laden droplets to form and settle onto cows. Clinical cases and chronically infected cows are a source of infection for healthy, young cows. If these mastitis cows are milked last, the risk of spreading infection is markedly reduced.

Wearing Gloves

Gloves should always be used, especially when searching for or dealing with clinical cases of mastitis.

A bare hand is more difficult to clean and disinfect during milking, than a gloved hand. Gloves also protect hands from the drying effects of dirt, water and manure.

Try to keep gloves clean during milking - rinse off dirt regularly and disinfect after stripping a clinical case. Change them if they become torn, and replace gloves after each milking.

Gloves, liners and equipment used to milk clinical cases will become contaminated with bacteria. Rinsing with running water for about 30 seconds provides a physical wash.

Dipping in a disinfectant solution, such as 1% iodophor or 0.02% available chlorine, provides a sanitising effect. Any physical rubbing or drying with a paper towel can speed up the rinsing/disinfectant process. Teat disinfectants are not generally recommended to disinfect hands or equipment, as they are formulated for a prolonged contact time.