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Virginia Cooperative Extension - Knowledge for the CommonWealth

Dry cow therapy is still a very important component of mastitis prevention and control

Dairy Pipeline: February 2002

Gerald M. (Jerry) Jones
Extension Dairy Scientist,
Milk Quality & Milking Management
(540) 231-4764;

The value of dry cow therapy has been the elimination of existing infections, especially new ones, at drying off and preventing new infections that develop during the dry period. Scientists from Compton Institute for Animal Health in the United Kingdom, in a paper published in Journal of Dairy Science's January issue, set out to determine if widespread use of dry cow therapy was still warranted and whether it could result in development of antibiotic resistance. They randomly assigned 236 cows from two Institute herds, with somatic cell counts averaging 150,000, and 54 cows from two organic herds, averaging 250,000 SCC, into dry treated and no dry treatment groups. Cows from the Institute herds were free of major infections, but Staphylococcus aureus was found in the herds going organic. About 2% of untreated cows developed clinical mastitis during the dry period, due to Streptococcus uberis. There were more new infections at calving in untreated cows (most were S. uberis and coliforms, but the Institute herds also had some S. aureus infections). The authors (E.A. Berry and J.E. Hillerton) concluded that dry cow therapy provides protection against new infections (reduced new infection rate by 80%) during the early dry period in herds with low somatic cell counts and low prevalence of infection. Also dry cow therapy prevented new S. aureus infections in higher SCC herds. In the latter herds, there were no spontaneous cures of S. aureus in untreated cows and only a 25% cure in older cows with high SCC in the treated group. Dry cow therapy is still a very effective measure for preventing new mastitis infections during the early dry period (against both S. aureus and Str. uberis). Although it was not reported in this study, dry cow therapy may be effective in curing new infections that develop before the dry period. Herds with higher SCC may have infections caused by S. aureus and as a result may want to consider dry treating bred heifers because some are infected before calving. Before administering any treatment into the teat, make sure that the teat end is CLEAN. After they have been milked, teat dip and dry after 30-45 seconds. Scrub teat ends with an alcohol pad. Avoid contaminating the infusion cannula; only insert it partially into the teat. Teat dip again before turning into a clean and dry environment.

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