24 July 2002

Teat seals oust antibiotics?

By Marianne Curtis

ANTIBIOTIC dry cow therapy could be a thing of the past for more than half the nations dairy herd after the launch of an internal teat seal later this year.

Trial results show the product to be better than antibiotics at preventing mastitis when used in suitable cows.

Speaking to delegates at the British Cattle Vet Associations summer meeting held in Newport, Gwent, last week, Bristol University researcher Andrew Bradley explained a new approach to mastitis control.

"Priorities at drying off are to remove existing udder infections and prevent new ones. Cows with somatic cell counts of more than 200,000/ml are likely to be infected with a major mastitis pathogen, so curing existing intra-mammary infections using antibiotics is a priority.

"There is no point in preventing new ones unless you have got rid of the ones already there."

But for cows with cell counts less than the 200,000 threshold, Dr Bradley questioned the use of conventional dry cow therapy. "Most antibiotic dry cow therapies fail to control coliform infections in the late dry period. The World Health Organisation and Food Standards Agency have also raised concerns about the preventive use of antibiotics in food producing animals."

Instead, low cell count cows could be treated with internal teat sealant – a non-antibiotic product with a toothpaste-like consistency – infused into teats at drying off, said Dr Bradley.

"This acts as a barrier, preventing bacteria from entering teats. It was first developed in Ireland in the early 1970s, but attracted little interest because of the rapidly expanding market for dry cow antibiotics. However, internal teat seals have been used in New Zealand since the mid-1990s."

Recent work conducted by Elizabeth Berry, researcher at the Institute of Animal Health and John Huxley at Bristol University shows promising results for the use of internal teat seals under UK conditions.

Selecting about 400 cows with cell counts less than 200,000, Dr Berry treated half with an internal teat seal and the rest were left untreated. "Untreated cows were 3.7 times more likely to have a new infection at calving than treated cows."

Teat seals also compared favourably with antibiotic dry cow therapy in Dr Huxleys study, which involved nearly 1000 cows, with yields varying between 4700 and 8500 litres. During the dry period, 11.1% of teat seal treated quarters became infected with major mastitis-causing bacteria compared with 15.4% of quarters for cows treated with a leading antibiotic dry cow tube.

"During the dry period, we saw two cases of clinical mastitis in the antibiotic group and no cases in the teat seal group." Although there was no difference in clinical mastitis cases in the first 100 days of lactation between the two groups, Dr Huxley suspects that had more cows been studied, there would have been fewer cases in the teat seal group.

Maker of the teat seal, Pfizer, expects to launch the product known as OrbeSeal this autumn, says Andrew Powell, who works for the company. "It will be a prescription only medicine available through vets and price will be a similar to dry cow therapies."

It is recommended for use on cows with average cell counts of less than 200,000/ml before drying off. NMR figures suggest just over half the UK herd falls into this category. &#42

&#8226 Suitable for low SCC cows.

&#8226 Prevent mastitis.

&#8226 Available in the autumn.