Effectiveness of Postmilking Teat Dips

Abstract

Two experimental approaches were used to estimate the relative efficacy of three germicidal preparations as postmilking teat dips. In successive trials of 17 and 7 months, chlorhexidine (.2%) and a commercial iodophor (1% available iodine) each reduced the overall new intramammary infection to 4 to 5 per hundred cows per month. Compared to the incidence among control cows, reductions due to teat dipping were 81 and 90% for staphylococci, 80 and 0% for streptococci (chiefly S. uberis), and 0% for coliforms and Pseudomonas species.In short trials of the chlorhexidine, the iodophor, a hypochlorite (4% available chlorine), and tap water, we evaluated change in magnitude of the natural staphylococcal population recoverable from apical teat skin by swabbing. Reductions of 95, 87, and 67% were achieved with the respective germicides. Results from tap water were erratic but indicated a small reduction in microflora.Efficacy was examined in relation to the number of cows previously dipped with the portion of dip solution during a single milking. There was no evidence of a reduction in germicidal activity through use of chlorhexidine on 22 cows, iodophor on 19 cows, or hypochlorite on 11 cows.