[Drying off cows: a comparative study with two dry cow products].

From September 1998 to September 1999, at drying off 397 cows on 73 Dutch farms were treated, with two antibiotic containing dry cow products (cloxacillin; penicillin-neomycin). Farms and cows were selected on an increased bulk milk somatic cell count (BMSCC) and individual cow somatic cell count. The objective of the trial was to compare the efficacy of both products under field conditions. Both products proved to be highly effective against streptococci and penicillin sensitive staphylococci. Because of the low incidence of infections caused by Escherichia coli and penicillin resistant staphylococci no conclusions could be drawn on differences in activity for these two pathogens. No significant differences were found between the two products in cure rate of existing infections at drying off, incidence of new infections during the dry period, incidence of clinical mastitis during the dry period and the course of the individual cow cell counts during the trial.