Effect of External Teat Sealant on the Prevention of Intramammary Infection for Milking Cows: A Randomized Cross-Over Design Study

This study clarified the effectiveness of external teat sealant (ETS) in preventing intramammary infections during lactation, using a cross-over study of two experiments (3 cows × 2 periods each) on a dairy farm. In Experiment 1, the control (Group A) received pre-dip and post-dip treatments, while the experimental group (Group B) received ETS application instead of post-dip treatment. In Experiment 2, Group C was treated the same as Group B, and Group D received ETS treatment only. After the intervention, teat ends were tested using ATP swabs, and milk collections from the first and last foremilk (Samples 1 and 2, respectively) were conducted over 4 days (8 times in total). In Experiment 1, the ETS application group exhibited lower ATP (<i>p</i> < 0.01) and bacterial counts (BC1, <i>p</i> = 0.02) compared to the control. Conversely, no differences in variables were observed in Experiment 2. The isolation rate of <i>Staphylococcus</i> spp. (>500 colony forming units) from Sample 2 in Groups C and D was significantly higher than that in groups A and B (<i>p</i> < 0.01). Replacing post-milking teat disinfection with ETS does not decrease viable bacterial counts and actually increases the proportion of <i>Staphylococcus</i> spp. ETS application is thus not an effective substitute for teat orifice disinfection.