THE EFFECT OF DISCONTINUATION OF POSTMILKING TEAT DISINFECTION IN LOWSOMATIC-CELL COUNT HERDS .2. DYNAMICS OF INTRAMAMMARY INFECTIONS

Results of a 20 month split-udder trial on the effect of discontinuati on of postmilking teat disinfection on intramammary infections (IMI) w ith major and minor pathogens in seven dairy herds with a low somatic cell count are described. The incidence of Escherichia coli IMI was fo und to be significantly lower, whereas the incidence of IMI with Staph ylococcus aureus and minor pathogens was significantly higher in quart ers for which postmilking teat disinfection was discontinued than in d isinfected quarters. It was concluded that discontinuation of postmilk ing teat disinfection decreased the incidence of E. coli IMI, accompan ied by a, from a practical point of view, acceptable rise in somatic c ell count. However, the possible increase in the incidence of S. aureu s IMI calls for careful monitoring of the dynamics of IMI with contagi ous pathogens, when postmilking teat disinfection is discontinued in a n attempt to reduce E. coli mastitis.