Clinical mastitis is caused mainly by environmental mastitis such as coliforms and Strep uberis. Staph aureus can also cause clinical mastitis but the importance of environmental bacteria causing clinical mastitis cases has increased as levels of Staph aureus have decreased.
The environment is the reservoir of infection with environmental mastitis. Infection is transmitted on or into the teats at three different times; between milkings if the cows are lying in dirty conditions or have faecal splashing onto teats after coming out of the parlour; during milking if there is poor teat preparation; or dry period infections.
Coliform infections mainly cause clinical mastitis while Strep uberis causes both clinical and subclinical mastitis and is often associated with straw bedding.
Mastitis infections can enter the udder during lactation and during the dry period. Lactation period infections occur when bacteria enter the udder during lactation, for example the spread of Staph aureus via the liner or an environmental infection if cows are lying on dirty beds.
Dry period infections are picked up when the cow is not lactating. These will almost always be environmental, such as coliforms and Strep uberis, as the risk of spread of contagious mastitis will be insignificant when a cow is not being milked.
Top tips to reduce environmental mastitis
Clean udders and teats
Udders and teats must be kept clean. The aim is to keep environmental bacte
ria away from the end of the teat. The best way to assess environmental cleanliness is to look at the teats and udder. You need to keep cows on clean, dry beds when housed. The beds are not clean enough if udders and teats are dirty when cows are housed. Tails should be trimmed and udders clipped or singed to minimise transferring dirt onto the teats. When cows are at pasture and weather conditions deteriorate, they often get dirtier than when housed.
Calving pens must be kept as clean as possible as freshly calved cows are most prone to mastitis. This is because their immune function crashes around the time of calving. This is why some
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