W2B-023 Biology matters-2.txt
Coliform mastitis a major killer

THE BOVINE mortality survey carried out by the Veterinary Science Division identified coliform mastitis, or acute environmental mastitis, as one of the major killers of adult dairy and suckler cows in Northern Ireland.

Unlike ordinary mastitis, the udder infection in the coliform version has been shown to be the result of exposure to bacteria that survive and, in the right conditions, multiply within the cow's environment.

It is most common during the winter months when cattle are housed, particularly from December to March, and often in milking herds which practice teat dipping and dry cow therapy.

The affect herds are usually well-managed, the husbandry is good and the cows are mainly housed in cubicles and fed silage.

SIGNS AND SYMPTOMS:

Typically, the condition occurs in freshly-calved cows in their fourth or fifth lactation. It is uncommon in calved heifers.

The bacteria involved are mostly the same as those excreted in cow faeces and E. coli are the most commonly isolated species - hence the general term coliform mastitis. Because these bacteria produce toxins, the affected animal is often suddenly very ill, after being quite normal at the last milking or feeding time.

The cow will be very depressed, sometimes down and unable to rise with a low body temperature - this can be confused with milk fever. There will be swelling or one of more of the mammary quarters with a watery mastitis.

The overall survival rate is usually only 50 per cent and urgent attention will be required from a veterinary surgeon who will use aggressive therapy, often including intravenous fluids, to save the life of the cow.

Quarter sampling, for culture and drug sensitivity at a laboratory, will indicate the best form of antibiotic treatment for use in future cases.

Recent evidence also suggests that stripping out of the infected quarter, every two or three hours, to remove the E. coli and its toxin, is a helpful procedure. Ironically, the infected quarter, although lost to the present lactation, will return to almost full production in the next lactation, provided the cow survives.

CONTROL MEASURES

Calving boxes: Obviously, it is important to reduce the level of faecal contamination in the cow's immediate environment.

Because freshly-calved cows have a depressed immune system, they are known to be more susceptible to coliform mastitis.

Consequently, it is essential to clean out calving boxes at regular intervals, certainly at least two-three times during the winter months and particularly after a coliform mastitis has occurred, as this indicates that the environment is heavily contaminated with E. coli

Cubicles: It is equally important to keep the the of the cow's environment as clean as possible.

Scrape out the backs of cubicles and passageways at least twice a day and bed down the cubicles at lease three times a week with sufficient material to make the cows use them.

Unfortunately, the bacteria can multiply in dirty, damp bedding, particularly if it is the type of material that could act as a compost, for example, materials such as sawdust, mushroom compost, chopped paper and peat. These will require more attention than biologically inactive materials such as crushed limestone, sand and rubber mats.

However, all of these are useless if they are contaminated and are continually damp because the ventilation within the cubicle house is inadequate. Dry bedding in a well-ventilated house with slotted roofs and Yorkshire cladding will inhibit the multiplication of E. coli.

Before and after milking: In the parlour, make sure that the cow's teats are cleaned and dried before milking.

Drying is particularly important, as washinh without it just produces a heavily contaminated drip at the end of each teat.

Also, make sure that the milking machine is cleaned adequately after each milking with a temperature that exceeds 85Deg C to ensure the destruction of coliform bacteria.

High Total Bacterial Counts (TBCs) are a sure sign that one, or all, of these tasks are not being done properly.

Finally, infection can also take place immediately after milking, particularly when the teat canal is still open and the cow leaves the parlour to lie in a dirty cubicle.

Closure of this canal takes 20-30 minutes and if the cow can be kept on her feet for this period, say at the silo face because she is hungry, then disease incidence will fall.

Reducing the concentrate levels in the parlour and closing the cows out of the silo for one-two hours before milking will have the desired effect.

CONCLUSIONS:

1. Coliform mastitis is caused by faecal organisms.

2. The condition is life-threatening, so seek immediate veterinary help.

3. Control measures should be aimed at reducing the environmental levels of E. coli.

4. Keep cows on their feet after milking.
