23 February 1996

BETTER HOUSING KEEPS MASTITIS BUGS AT BAY…

Environmental mastitis refuses to go away. Improved cow housing is the answer. Jessica Buss reports

MILK producers must improve cow housing to reduce environmental mastitis incidence.

This was the message from Leicestershire vet Peter Orpin who reports that 20% of toxic mastitis cases are fatal.

Mr Orpin claims that many cases occur soon after calving. "In one large herd 20% of cows suffered clinical cases of mastitis, and half of these were in the first month of lactation," he says. "This results in lost production and cows failing to achieve expected lactation yields. This was not due to poor dry cow therapy but more likely infected calving yards."

Schering-Plough vet Tony Fraser cites recent survey results to show that the incidence of environmental mastitis is as high as it was 25 years ago. In the same period total clinical cases have reduced to 25% of the initial number mainly due to the five-point plan for mastitis control.

Environmental mastitis

"The cost of environmental mastitis depends on the seriousness of the case and many factors need to be considered," says Mr Fraser. These include discarded milk, loss of yield, vet treatment and culling and this could add up to £3250 a year for a typical 100-cow herd.

The two bacteria that cause environmental mastitis, s.uberis and E.coli are ever present in housing, bedding and slurry, he adds.

Mr Orpin warns that in straw yards bulling cows stir up bedding. To avoid environmental mastitis it is important yards are mucked out every six weeks to stop heat building up and prevent bacteria growing.

Improving ventilation also helped by keeping the humidity down, for mastitis bugs like moist conditions.

Mr Orpin also warns against overcrowding. "An extra five cows in a yard designed for 75 will increase the mastitis incidence."

Environmental mastitis is also a problem in cubicle housed cows especially when cows or heifers refuse to lie in them.

Cubicle design

"Cows are trying to tell you something about the cubicles when they refuse to lie in them. When a heifer has a bad experience in a cubicle she may not lie down for a week," says Mr Orpin.

"Although lime is useful, a vast amount cannot help a cubicle that has a dung pat on it. Cubicle design must also be right."

There is often speculation that low cell count herds could be more susceptible to environmental mastitis. But he emphasis that in high cell count herds it is often two cows contributing 40% of the cells, and in fact most of the rest of the cows in these herds also have low cell counts.

Persistently high cell count cows with a history of repeated mastitis should be culled.

Dry cow therapy at the end of lactation clears up any udder infections including those that remain after the treatment of clinical cases.

Mr Orpin adds that to expect a 100% cure of mastitis from three milking cow tubes is unrealistic, if cows were treated for 10 days cure rates would improve – but this would be uneconomic in terms of drug costs and milk discard. Your doctor would not prescribe antibiotics for three days but we expect this to be enough for cows.

Faster milking, higher yielding cows with large teat sphincter size are more prone to environmental mastitis. It is important the sphincter closes before the teat comes into contact with bedding. He suggests feeding cows after milking to keep them standing for 20 to 30 minutes.

"Mastitis incidence also appears to be related to cow stress. One that has suffered a difficult calving, twins or milk fever or that is bulling is under stress, she will struggle to beat infection," says Mr Orpin. &#42


&#8226 Reduce cow stress.

&#8226 Use dry cow therapy.

&#8226 Provide adequate bedding.

&#8226 Muck out yards every six weeks.

&#8226 Do not overcrowd housing.

&#8226 Improve ventilation.


IMPROVING CONTROL

Faster milking, high yielders with large teat sphincters are more prone to environmental mastitis – keep them standing for 20 minutes post-milking.

Good ventilation helps reduce the humidity favoured by mastitis bugs.