J. S. Hogan1 and K. L. Smith
The Ohio State University Department of Animal Sciences
Environmental streptococci have emerged as pathogens that uniquely affect mammary health as a primary cause of both subclinical and clinical mastitis. The bovine mammary gland appears to be most susceptible to environmental streptococcal intramammary infections during the dry period and early lactation. Resistance of cows is critical to the control of environmental streptococcal mastitis, and little doubt exists that healthy teat ends and a properly functioning immune system are critical to the maintenance of low numbers of infected quarters and the elimination of infections that do occur. As cows are bred for greater and greater milk production, their susceptibility to intramammary infection is increasing. Exposure of teat ends to the environmental streptococci can overwhelm good immunity under most conditions. Effective control of the environmental streptococci in the short term is most likely to be achieved by reducing teat end exposure. Exposure is the major risk for environmental streptococcal mastitis in current dairy herds, and we need to continually learn ways to keep cows clean, dry, cool, and comfortable.
1 For more information, contact at: The Ohio State University, Ohio Agricultural Research and Development Center, 302 Pounden Hall, 1680 Madison Avenue, Wooster OH 44691, 303-263-3801, Fax 330-263-3949, e-mail: hogan.4@osu.edu