Mastitis control in bred dairy heifers using dry cow therapy and teat sealant to prevent new infections and to cure existing ones

Abstract

Objective: Is use of dry cow therapy, teat sealant, or dry cow therapy + teat sealant more effective in controlling heifer mastitis and decreasing SCC than no treatment? Materials and Methods: At 2 mo prepartum, 304 mammary quarters of 76 pregnant Holstein heifers were randomly assigned to (1) dry cow therapy, (2) teat sealant, (3) dry cow therapy + teat sealant, or (4) untreated control. Before treatment, mammary secretion samples were collected and stored for bacteriological analysis. After calving, infection data were compared with data collected prepartum, and treatment means were separated using SAS 9.3. Results and Discussion: Compared with cure rate in untreated controls (55.2%), treatment with dry cow therapy (100%), teat sealant (85.7%), or dry cow therapy + teat sealant (96.1%) resulted in greater cure rates and lower SCC in quarters infected prepartum with Staphylococcus aureus or coagulase-negative staphylococci. Prevention rates against all new intramammary infections (IMI) were similar for control quarters (95.9%), dry cow therapy (92.2%), teat sealant (97.9%), and dry cow therapy + teat sealant (95.9%). Implications and Applications: Although the IMI prevention rates were similar across treatments, the majority of heifers did have at least one quarter infected with Staph. aureus or coagulase-negative staphylococci, which dry cow therapy has been shown to be very effective in curing as well as decreasing future SCC. In problem herds, an udder health program should incorporate treating all quarters with dry cow therapy to cure existing IMI plus teat sealant to prevent new IMI, under supervision of the herd veterinarian.