Environmental Pathogens and Intramammary Infection During the Dry Period

Rate of coliform and streptococcal intramammary infection during the dry period was studied in 168 dry periods. Coliform infection rate was influenced by stage of dry period, parity, and season during which dry periods occurred. Effects of dry cow therapy, immunization, or induced inflammation on coliform infection rate were minimal. Coliform infections originating in the first 50% of the dry period and persisting to lactation were predominantly other than Escbericbia coli, whereas the majority originating in the last 50% of the dry period and persisting to lactation were Escbericbia coll.