21 December 2001

Mastitis thrives in loose-housed milker holdings

By Jessica Buss

CLINICAL mastitis and somatic cell counts are proving hard to control in loose-housed milkers with increases in stocking density, straw shortages and a warm autumn contributing to the problem.

Peter Edmondson of the Shepton Vet Group, Somerset, has been called to many farms, loose housing cows with high numbers of clinical cases and cell counts persistently high at 200,000-275,000/ml.

Careful check

Even when there is enough lying area for cows, milkers are forced to stand after milking, parlours pass a careful check and teat preparation is good, some farms are still having problems. But high straw prices are forcing some producers to cut use, he adds.

He identifies the bacteria Strep uberis as the key concern. "Without early detection and treatment, this bug will cause repeat cases of mastitis in the same cow. This makes careful fore-milking essential and pre-dipping may also help."

The warm early winter and bringing in cows early have helped this bug establish in yards, causing high bacterial counts. He, therefore, advises cleaning out yards frequently, every three or four weeks, this winter.

But Shropshire-based mastitis specialist, John Hughes believes even this may not be often enough. "After two weeks there are enough coliform and uberis bacteria on the bed to challenge any cow."

This rapid bacterial growth occurs because 8cm (3in) under the bed surface a fermentation layer forms where the temperature reaches 40-50C. That heat rises to the surface making the straw bed warm and sticky.

Recent humid weather has contributed to the problem, as it makes ventilation difficult, keeping moisture within the building. "A cow produces 70 litres of water in muck and urine a day," he adds. Drips from the ceiling are a sign of inadequate ventilation.

Cleaning out frequently will help. "Some producers complain they see mastitis after they have cleaned out the shed. This is because the shed base is cold and cows udders are chilled, so when starting a new bed insulate it with a layer of rape, pea or bean haulm and then a layer of barley straw."

He also suggests splitting sheds so they are one-third concrete. But any step between concrete and straw should be no more than 12.5cm (5in) high to keep cows udders out of slurry.

Concrete should also be scraped often, although labour cutbacks are making this difficult, adds Mr Edmondson. Failing to do so and cutting back on straw will lead to dirty cows. "When cows look dirty, they are being exposed to faeces which increases clinical mastitis risks."

Environmental

Because Strep uberis is an environmental type mastitis, herds troubled by this bug will see most clinical cases during the winter months. But more than five cases/100 cows in a month requires some action, he says.

For producers considering building straw yards to accommodate extra cows, the higher incidence of clinical mastitis should be considered in costing the project. "Although yards are cheaper to install than cubicles, consider the costs of mastitis over a long period. It is also necessary to use 2t of straw a cow each winter. This year that is costing some producers £200 a cow."

Bedding advice

Straw can be used more effectively by bedding cows twice a day, says Mr Hughes. "Cows should go on to a clean bed after each milking. But use one-third of the straw allocation in the morning and two-thirds at night when they spend longer on the bed."

For dry cows, he suggests using a layer of sand under the straw (Livestock, Dec 7). "However, milkers produce too much muck, so sand should not be used in loose yards." But it is a good alternative to straw in cubicles, advises Mr Edmondson. &#42

REDUCING MASTITIS

&#8226 Muck out yards frequently.

&#8226 Check ventilation.

&#8226 Bed up twice a day.

REDUCING MASTITIS

&#8226 Muck out yards frequently.

&#8226 Check ventilation.

&#8226 Bed up twice a day.