Dairy Resources

Mastitis continues to be a major livestock disease afflicting the U.S. dairy industry. As the industry strives to improve milk quality to meet consumer as well as exportation demands, the legal limit for bulk tank sec will likely be reduced from 750,000/ml to 400,000/ml in the near future. It is estimated that between 10 and 20% of US dairy farms, mostly located in the Southeast, are currently at or above the 400,000/ml SCC limit and will have to adopt stricter methods for controlling mastitis in their milking herds, dry cows, and heifers.

This publication reviews the survey results of adoption rates for mastitis control measures and shows that there is much room for improvement.

Antibiotic therapy continues to play an important role in the control of mastitis in dairy cows. Lactational therapy is effective against Streptococcus agalactiae but less successful against infections caused by Staphylococcus aureus and other causes of mastitis. As a result, alternative treatment strategies have been developed, including a combination of both intramammary infusion and the parenteral administration (injection) of antibiotics to successfully cure quarters infected with S. aureus. Likewise, extended therapy, which involves prolonged drug administration, has improved cure rates against this organism. Nonantibiotic approaches to treatment have included oxytocin injections, but relapse rates after this form of therapy can be unacceptably high. Dry or nonlactating cow therapy is almost always more successful than lactational therapy because cure rates are higher and new cases of mastitis are prevented. To reduce antibiotic usage, selective dry cow therapy is becoming popular, and teat seals are appealing because they prevent new infections without having to rely on antibiotics.

Due to cows’ universal exposure to manure, which contains E. coli and other gram-negative bacteria, as well as the requirement to maintain sec as low as possible, all cows should be vaccinated with one of the coliform vaccines available on the market. These vaccines have been proven to significantly reduce clinical coliform mastitis and have been shown to be profitable when incidence of clinical coliform mastitis exceeds 1% of milking cows.

According to the National Mastitis Council, the recommended milking procedure for dairy animals is 1) provide low-stress environment, 2) check foremilk and udder for mastitis, 3) wash or predip teats with an effective disinfectant, 4) completely dry teats with a single-use towel, 5) attach milking unit within 120 sec of teat stimulation, 6) adjust milking units as necessary, 7) shut off vacuum for removing the unit, and 8) dip teats with a postdip disinfectant. One of the most critical steps in this recommended routine is checking foremilk to not only ensure there are no signs of mastitis and to maintain milk quality, but also to effectively stimulate the teats in preparation for milk collection. Thus, stripping the first three to five streams of milk (foremilk), during the premilking routine serves three important purposes including: teat stimulation which can result in optimal milk release, enhanced milk quality by removing the highest bacterial and somatic cell count milk, and identification of mastitis to allow rapid, well-informed decisions regarding further evaluation, milk culturing, and/or antibiotic therapy. This publication will discuss the purposes of forestripping for dairy animals to serve as an educational resource when creating and evaluating best milking practices.