Efficacy of barrier-type postmilking teat germicides against intramammary infection

Two barrier tear dips were evaluated for efficacy in preventing new IMI by Staphylococcus aureus and Streptococcus agalactiae during experimental exposure trials, and two barrier dips were evaluated during natural exposure trials. Dipping in an experimental product containing nicin as germicide using experimental exposure demonstrated no difference in rate of new Staph. aureus IMI (10.2%) compared with that of controls (7.1%) or in the rate of new Strep. agalactiae IMI (13.6%) compared with that of controls (11%). Testing of an experimental .55% chlorhexidine gluconate barrier dip using experimental exposure resulted in an increased rate of new Staph, aureus IMI compared with that of controls (4.8 vs. 1.7%, respectively), but no difference in the rate of new Strep. agalactiae IMI in dipped quarters (6.1%) compared with that of controls (3.3%). Dipping with a commercial .3% iodine barrier dip during natural exposure increased the number of new coagulase-negative staphylococcal and total IMI by 56.6 and 30.6%, respectively, compared with a 1% iodophor dip without barrier. Use of an experimental .3% iodine barrier dip during natural exposure demonstrated no difference in total rate of new IMI (18.4%) compared with that of controls (20.3%); however, after germicide concentration was increased to .5% iodine and further tested, the reformulated product reduced new IMI by 43.1%. Under the conditions of these trials, the barrier teat dips tested were no more efficacious than no teat dip or using a nonbarrier product.