Evaluation of 1.6/100 Phenol as a Premilking and Postmilking Teat Dip in Preventing New Bovine Intramammary Infections

摘要

We evaluated the effectiveness of a 1.6/100 phenol- based teat dip using both a teat skin assay and natural exposure field trial. A teat skin assay was conducted to ascertain the concentration of phenol + phenate to be used in the field study. One percent and 0.5/100 iodine, and 0.5, 1.1, and 1.6/100 phenol + phenate were compared using Escherichia coli and Staphylococcus aureus. Log- arithmic reductions for S. aureus were 2.2 and 2.8 for 0.5 and 1/100 iodine, and 1.3, 2.1, and 2.8 for 0.5, 1.1, and 1.6/100 phenol + phenate, respectively. Logarithmic reductions for E. coli were 3.3 and 3.8 for 0.5 and 1/100 iodine, and 1.2, 1.9, and 2.6 for 0.5, 1.1, and 1.6/100 phenol + phenate, respectively. A concentration of 1.6/100 phenol + phenate was chosen as experimental teat dip, and 0.5/100 iodine served as control. The field study was con- ducted at Beltsville (n = 185) and Clarksville (n = 100) dairy herds using a split herd design. Teat dips were used premilking and postmilking for 12 mo. The num- ber of new intramammary infections (IMI) for the Belts- ville herd in iodine and phenol + phenate teat dipped cows were: 29 and 35 for major pathogens, and 81 and 72, for minor pathogens. For the Clarksville herd, num- ber of new intramammary infections in iodine and phe- nol + phenate teat dipped cows was 9 and 10 for major pathogens, and 50 and 60 for minor pathogens. Rates of IMI per quarter day per lactation were not different for either herd or when herd data were combined. The number of clinical mastitis cases per 100 cows per month were similar in both treatments. The incidences of new IMl and clinical mastitis were similar using both dips.