Effect of 2 different premilking teat sanitation routines on reduction of bacterial counts on teat skin of cows on commercial dairy farms

Premilking teat sanitation reduces the load of bacteria on teat skin before milking and it is a fundamental practice used to ensure collection of high-quality milk. The objective of this study was to compare reduction in bacterial populations of teat skin after premilking preparation using either predipping with 0.5% iodine followed by drying (conventional; CONV) or using a semiautomated teat scrubber that uses chlorine dioxide (TS; FutureCow, Longwood, FL). Ten farms currently using a commercial teat scrubber system were enrolled. Cows (n = 40 per farm) were assigned to CONV (n = 198) or TS (n = 196) premilking udder preparation. Teat skin swabs were collected before and after udder preparation and analyzed for total bacterial count (TBC), Streptococcus spp., Staphylococcus spp., and gram-negative bacteria (GNB). Reduction (RED) of each bacterial group was defined as the difference in the number of bacteria measured before and after udder preparation. Before udder preparation, Staphylococcus spp. (15,036 cfu/mL) and Streptococcus spp. (12,621 cfu/mL) were the most numerous microflora. Gram-negative bacteria were less numerous (1,538 cfu/mL). A significant treatment by farm interaction was identified for RED of all bacterial counts. Compared with teats prepared using TS, teats prepared using CONV preparation had greater RED of TBC on 3 farms, of Streptococcus spp. on 2 farms, and of Staphylococcus spp. on 1 farm. On all other farms, RED in TBC, Streptococcus spp., and Staphylococcus spp. did not differ based on teat preparation method. Use of TS resulted in greater RED of GNB of teats on 3 farms, but RED in GNB was greater for teats cleaned by CONV on 1 farm; for the other 6 farms, RED of GNB did not differ between methods. For all bacterial counts, an effect of chlorine dioxide concentration used in the teat scrubber was observed. Results from this study suggest both CONV and TS can effectively reduce bacterial counts, but farm conditions and management practices can have a significant effect on the effectiveness of teat disinfection.