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Staph Mastitis: Herd Control Program

Clell V. Bagley DVM, Utah State University


Mastitis caused by Staphylococcus aureus is a major problem for some dairy herds. It causes high Somatic Cell Counts (SCC), reduces milk quality, and may cause a loss of milk market. It limits milk production for the herd, reduces efficiency, and continues to spread to other cows. Most herds have some Staph infected cows. But the Staph infection tends to spread and become much worse with poor milking-preparation procedures, frozen teats, severe malfunction of the milking machine, and deficiency of vitamin E or selenium. It is probably not possible to eradicate this organism from a herd, but it is extremely important to keep it under control. Staph is the most common form of contagious mastitis. The reservoir of infection is the udder of infected cows, and the organism is spread from infected to clean cows, primarily during milking preparation and the milking process. It is easily carried on hands or equipment from one udder to another. Cows infected with Staph are often not evident and special testing is needed to identify them. Not all will have a high SCC (30% may be below 300,000). There is great variation from herd to herd in the severity of mastitis, response to treatment, and benefit of vaccination.