Effectiveness of Dry Cow Therapy Comprising Antibiotic Treatment, Internal Teat Sealant, and α-Tocopherol Against New Intramammary Infections in Cows

The aim of this study was to evaluate the preventive effectiveness of dry cow therapy based on antibiotic, internal teat sealant, and α-tocopherol administered separately or in various combinations at drying-off The study was performed on 322 uninfected quarters of 95 cows originating from three dairy herds. The new intramammary infection rates after calving were measured to evaluate the effectiveness. The quarters were divided into six groups differing in treatment, namely: control group (group C, n = 40) and five treatment groups. Treatment groups were arranged as follows: group A (antibiotic alone, n = 81), group AS (antibiotic + sealant, n = 40), group AST (antibiotic + sealant + α-tocopherol, n = 40), group T (α-tocopherol alone, n = 40), group S (sealant alone, n = 81). New infection rate amounted to 47.5% in group C. The treatment in group AST significantly prevented from the occurrence of new intramammary infections (12.5%, P < 0.05), especially those caused by major pathogens. Antibiotic treatment alone (group A) did not prevent from new infections (34.6%, P > 0.05), although the use of the sealant alone (group S) decreased the risk of new infection (24.7%, P < 0.05). A decrease in new infection rate (25%, P < 0.05) was also observed in AS group treated with the combination of the sealant and antibiotic. α -tocopherol supplementation alone (group T) had no overall effect on new infections (35%, P > 0.05). Increased α-tocopherol level (P < 0.05) was detected after calving in the quarters from cows that received α-tocopherol injections. In conclusion, the combination of antibiotic, internal teat sealant, and α-tocopherol used in dry cow therapy showed a significantly better preventive effect against new intramammary infections, than the therapeutics administered separately.