You've reached the Virginia Cooperative Extension Newsletter Archive. These files cover more than ten years of newsletters posted on our old website (through April/May 2009), and are provided for historical purposes only. As such, they may contain out-of-date references and broken links.

To see our latest newsletters and current information, visit our website at

Newsletter Archive index:

Virginia Cooperative Extension - Knowledge for the CommonWealth

The transition period may be too late in the dry period to prevent new mastitis infections

Dairy Pipeline: August 2001

Gerald M. (Jerry) Jones
Extension Dairy Scientist,
Milk Quality & Milking Management

E. coli and environmental streptococci are most likely the cause of most mastitis infections in well managed udders with low somatic cell counts. Data from English herds showed that over half of clinical mastitis caused by coliforms became established in the udder during the dry period. Any infections that are established during the dry period are likely to persist and result in clinical mastitis. The English study found that new E. coli infections detected at calving had become established by three weeks before calving. Consequently, although a herd may have treated every cow at drying off, moving cows into a transition group housed in an area with cleaner and drier environment, and feeding small amounts of grain containing vitamin E and selenium may be helpful but also may be too late. Environments with muddy or denuded lots, dirty and wet bedding, poor ventilation, or access to wet areas such as ponds, streams, or shade trees from the time of drying off until entering the transition group may have caused these new infections. These don't show up until 30-60 days after calving. Here's some things to review. Check breeding records and allow 50-70 day dry periods. Dry off early any cows producing less than 20 lb. milk per day or that has a somatic cell count above 200,000 or score of 4 or above. Properly administer a dry cow treatment proven effective against environmental infections. Culture cows after calving and request antibiotic sensitivity test results to assist you in determining if an antibiotic might be ineffective in your herd. Prior to treatment, dip teats and allow 30 seconds before drying thoroughly, scrub teat ends with alcohol, partially infuse treatment only into the teat canal, and teat dip again. Consider giving E. coli vaccine. Body condition score cows at drying off and work with a nutritionist to feed a ration that is formulated for your herd's conditions. Consider rotational grazing for dry cows. Implement an effective fly control program which includes elimination of fly breeding sites in decaying feed or manure that has accumulated in exercise yards, calf pens, and box stall and use backrubbers or dust bags, feed additives, ear or tail tags, and parasitic wasps as appropriate. Keep dry cows separate from bred heifers.

Visit Virginia Cooperative Extension