Reduction of Mastitis Caused by Experimental Challenge with Staphylococcus aureus and Streptococcus agalactiae by Use of a Quaternary Ammonium and Halogen-Mixture Teat Dip

¹ Mastitis Research Laboratory, Hill Farm Research Station, Louisiana Agricultural Experiment Station, Louisiana State University Agricultural Center, Homer 71040

A teat-dip formulation containing sodium dichloro isocyanuric acid, bronopol, and quaternary ammonium was tested for efficacy against Staphylococcus aureus and Streptococcus agalactiae intramammary infections (IMI) using an experimental challenge model. Sixty-two Jersey cows from the Hill Farm Research Station (Homer, LA) were used in an 8-wk controlled infection trial to evaluate the teat dip. During the afternoon milking, Monday through Friday for 8 wk, all teats of each cow were immersed to a depth of approximately 25 mm in a challenge suspension containing approximately 5 x 10⁷ cfu of Staphylococcus aureus and approximately 5 x 10⁷ cfu of Streptococcus agalactiae immediately after milking machines were removed. Immediately after challenge, the distal 25 mm of two contralateral teats were dipped with the experimental teat dip; the remaining two teats served as undipped controls. The experimental teat dip reduced the number of new Staph. aureus IMI by 70.9% and reduced the number of new Strep. agalactiae IMI by 60.0%. Teat end and teat skin condition were characterized as normal and without irritation at the completion of the study. The combination of the three germicides in this experimental teat dip is unique and an effective formulation without adverse effects on condition of teat ends or teat skin.

Key Words: sodium dichloroisocyanuric acid • bronopol • quaternary ammonium • teat dip

Submitted on June 25, 2001
Accepted on October 9, 2001