[The Effect of Selective Dry Cow Treatment on the Udder Health in Swiss Dairy Farms]

The aim of the present study was to determine the effects of selective dry cow treatment (SDCT) on udder health in Swiss dairy farms compared to a blanket dry cow treatment (BDCT). Cows with a somatic cell count (SCC) of less than 250'000 cells/ml and after BDCT in the previous dry period were selected. These animals received a SDCT in the subsequent dry period. Cows with less than 150,000 cells/ml or a negative California mastitis test (CMT) received either no treatment (group oB) or an internal teat sealant (group ZV) in all teats. Cows with more than 150,000 cells/ml or a positive CMT were treated with antibiotics and teat sealants (group ZV+AB). The SCC before and after the dry period were determined. In addition, the incidence of mastitis treatments in the dry period and the first 100 days of the following lactation as well as rates of new intramammary inflammations and healing thereof were determined. Data from 115 cows were available for evaluation. The SCC postpartum of all cows after SDCT did not differ from those after BDCT in the previous year. In the group oB the SCC was significantly higher than in the previous year. While the group ZV+AB showed a significant decrease of SCC during the dry period, the other two groups showed an increase (p < 0.0001). In the group oB, the proportion of mastitis treatments increased from 0% after BDCT to 28% after SDCT without any udder treatment (p < 0.05). Due to the increasing problem of antimicrobial resistance, SDCT is a valuable alternative to the BDCT. In the present study the antibiotic consumption could be reduced by 63%, while the udder health after SDCT did not deteriorate. If cows with low SCC are dried off without antibiotics the end of lactation, it is beneficial to protect the udder during the dry period with a teat sealant.