EFFICACIES OF TEAT GERMICIDES CONTAINING 0.5-PERCENT CHLORHEXIDINE AND 1-PERCENT IODINE DURING EXPERIMENTAL CHALLENGE WITH STAPHYLOCOCCUS-AUREUS AND STREPTOCOCCUS-AGALACTIAE

Two germicides, one containing 0.5% chlorhexidine and one containing 1 % iodine, were tested for efficacy against new intramammary infections (IMI) caused by Staphylococcus aureus and Streptococcus agalactiae. T he model for the experimental challenge in the trials that were design ed to test the efficacy of the two postmilking teat dips was recommend ed by the National Mastitis Council. The 0.5% chlorhexidine product re duced the number of new IMI caused by Staph. aureus by 73.2% and reduc ed the number of new IMI caused by Strep. agalactiae by 53.9%. The 1% iodine product reduced the number of new IMI caused by Staph. aureus b y 75.6% and reduced the number of new IMI caused by Strep. agalactiae by 53.5%. In both trials, the incidence of clinical mastitis was also reduced in dipped quarters compared with control quarters. Use of the two teat dips over the trial periods had no effect on the condition of teat skin or teat ends.