E coli is a major economic cause of mastitis on the modern dairy farm.
Infection can range from a mild sub-acute clinical to a severe life-threatening illness. Severely-affected cows show such symptoms as high temperature, inflammation of the udder (usually just one quarter), lack of appetite, dehydration, diarrhoea and abnormal milk.
Death can result from endotoxin released by the bacteria overwhelming the cow. Mild cases show as a mastitis with thin or serum-like ‘milk’ and large white flakes, although the appearance of the milk is not diagnostic for E. coli mastitis it is suggestive.
This bacteria is one of the most common found in the gut and is consistently passed out into the environment in the faeces.
General cleanliness, correct stocking densities and a comfortable clean dry bed all have a beneficial effect not only in preventing E coli and other forms of environmental mastitis, but also on the incidence of lameness. Good drainage and ventilation reduce humidity and lead to dry conditions that have a major effect on the coliform bacteria, drying kills 80%-plus within minutes.
The quality and management of bedding is of great importance. Straw that has become wet in storage or was baled at a high moisture content has reduced absorbency and can predispose to mastitis.
When straw is used in cubicles, slaked lime or powdered ground limestone can be used to help keep the bed dry. Of these the limestone is the cheaper and is probably gentler on the teats. Sawdust can predispose to environmental mastitis.
Sand is a good inert bedding material, which minimises all bacterial growth. It is important to use the correct type of sand, which must be free-flowing and not compact into a solid mass. The correct depth of sand must be used and this should be at least 4in/10cm, to avoid it being uncomfortable. Care should be taken when considering sand as it can cause substantial damage to certain types of slurry handling systems.
Cubicles should be checked at least twice daily to remove contamination. And passageways should be scraped at every milking to reduce contamination of the beds by dirty feet and splashing of teats.
Teat hygiene and preparation must be fastidious. Dry teats are essential for milking, a dry wipe should in most cases be all that is required; washing should only take place if the teats are dirty and they should then be thoroughly dried. It has been a benefit in some herds to pre-disinfect and wipe the teats before milking.
Post-milking teat disinfection is recommended, though in some cases dipping appears to have increased the incidence of coliform infections.
One of the simplest recommendations is to keep cows standing in a clean area for 30 minutes after milking to allow for adequate teat end closure, so creating a physical barrier to contamination. This is not possible in some systems but can be achieved by ensuring that fresh feed is ready for the cows on return to the shed.
On farms with continuing problems, vaccination can be a useful tool for prevention; this can be discussed with your vet and should be noted in your herd health plan.