Effect of 2 different pre-milking teat sanitation routines on reduction of bacterial counts on teat skin of cows on commercial dairy farms.

Pre-milking teat sanitation should reduce the load of bacteria on the teat skin before milking and it is a widely accepted practice used to ensure collection of high-quality milk. However, different procedures are on offer and the question is how do the different procedures compare. This was the basis of an investigation by Dr C Baumberger and colleagues, which was published in the Journal of Dairy Science, Volume 99 of 2016, page 2915 to 2929, with the title: Effect of 2 different pre-milking teat sanitation routines on reduction of bacterial counts on teat skin of cows on commercial dairy farms.

The objective of their study was to compare the reduction in bacterial populations of teat skin after pre-milking preparation using either pre-dipping with 0.5% iodine followed by drying (conventional; CONV) or using a semi-automated teat scrubber that uses chlorine dioxide (teat scrubber; TS). Ten farms which use a commercial teat scrubber system were enrolled in the study. Forty cows per farm were respectively assigned to the CONV or the TS pre-milking udder preparation. Teat skin swabs were collected before and after udder preparation and analyzed for total bacterial count (TBC), Streptococcus species (spp.), Staphylococcus spp. and gram-negative bacteria (GNB). The reduction in each bacterial group by CONV and TS was defined as the difference in the number of bacteria measured before and after udder preparation.

Before udder preparation, Staphylococcus spp. (15000 cfu per mL) and Streptococcus spp. (12600 cfu per mL) were the most numerous bacteria. The gram-negative bacteria were less numerous (1550 cfu per mL). The difference between CONV and TS in capacity to reduce bacterial count was not the same on all farms: Compared with teats prepared using TS, teats prepared using CONV preparation had greater reduction of TBC on three farms, of Streptococcus spp. on two farms and of Staphylococcus spp. on one farm. On all other farms, the reduction in TBC, Streptococcus spp. and Staphylococcus spp. did not differ due to teat preparation method. The use of TS resulted in greater reduction in GNB of teats on three farms, but the reduction in GNB was greater for teats cleaned by CONV on one farm. For the other six farms, the reduction in GNB did not differ between the two methods.

The results from this study show that 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. It is therefore suggested that the methods should be meticulously employed to ensure effectiveness.