INTERNAL TEAT SEALANTS FOR DAIRY COWS: A REPLACEMENT FOR A MECHANISM OF INNATE IMMUNITY

CARNEIRO D. V., VAZ A. K.(1)

(1)CAV/UDESC,  Department. MVPT, Lages, SC, Brazil

When the mammary gland of dairy cows stops producing milk in the interval between two lactations, a keratin plug is formed in the teat canal. This plug has bacteriostatic properties and blocks the entry of microorganisms in the gland. Many cows, especially high production animals, delay the formation of this plug for over two weeks. To prevent infections during this period, antibiotic treatment after the last milking before the dry period is used in all cows, but this can lead to residues in milk and increase antibiotic resistance. To imitate this innate immunity mechanism, internal tet sealants, based on paraffin and bismuth subnitrate, were developed. They are applied into the teat canal immediately after drying off, and remain in place during the dry period (usually 60 days). The objective of this study was to evaluate the effect of one  sealant (MASTBLOCK, IRFA Química e Biotecnologia) on the rate of self-cure during the dry period. We compared the effect of this sealant when used alone, in association with an antibiotic (gentamicin) and the antibiotic alone. All mammary quarters (N=105) were infected with mastitis-causing bacteria at drying off. In each cow, one quarter was infused with the sealant alone (T1, N=24), one was infused with antibiotic  followed by the sealant (T2, N=29), and  two received antibiotic only (T3, N=52). Milk cultures were done one week before drying off, at drying off, 8 and 21 days after the beginning of the next lactation. Self-cure rate was not significantly different (p>0.01, Fischer's Exact Test) among T1 (87,5%), T2 (93,1%) and T3 (90,4%). These results suggests that there is no difference among the use of an antibiotic or an internal teat sealant, under the conditions of this study.

KEY WORDS: cow, mastitis, keratin plug

CORRESPONDENCE TO:

A.K. Vaz, Caixa Postal 281, 88502-970 Lages, SC, Brasil. Email adilvaz@cav.udesc.br