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.
8.1 - Wear gloves when milking
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.
8.2 - Use running water and disinfectant solution to remove infected milk
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.
8.3 - Draft out clinical cases into a separate mob, and milk them last
SmartSAMM recommends that cows with newly detected clinical mastitis should be drafted out and milked last, after the milking herd has been milked.
Cows under treatment with antibiotics should also be milked last, in a separate mastitis herd, once the vat has been disconnected from the milkline.
The whole milking machine should then be washed with a full hot water wash to remove any residues of milk contaminated with bacteria or antibiotics. If it is not possible to run a separate herd, make sure that treated cows are well marked, that they are drafted out of the herd at each milking, and then milked last, once the delivery line has been disconnected from the vat.
See Guideline 4 for more on MRS T - Marking, Finding, Separating and Treating cows with clinical mastitis.
8.4 - Reduce the risk of spreading infection by identifying infected cows and milking them last
It may be feasible and more time efficient to run a separate herd for clinical cases and/or high SCC cows.
See Technote 8 for more on the value of running seperate herds to reduce infection.