A teat disinfectant containing a phenolic combination was evaluated in a natural exposure study in two dairy research herds. Premilking teat disinfection was compared with a negative control using a split-udder experimental design. In both herds, premilking and postmilking teat disinfections with the phenolic combination were significantly more effective in preventing new intramammary infection (IMI) than was postmilking teat disinfection only. Clinical mastitis and new IMI by Streptococcus uberis, Streptococcus dysgalactiae, Gram-negative pathogens, and coagulase-negative Staphylococcus species were significantly lower in quarters of cows with teats predipped and postdipped than in quarters with teats postdipped only. No chapping or teat skin irritation was observed. Premilking teat disinfection with the phenolic combination in association with good udder preparation and postmilking teat disinfection can further reduce the occurrence of new IMI by numerous mastitis pathogens during lactation.
Summary
Adherence of an encapsulated (UT 101) and a non‐encapsulated (UT 102) strain of Streptococcus uberis to a bovine mammary epithelial cell line (MAC‐T) and to extracellular matrix proteins (ECMP) including fibronectin, collagen and laminin was investigated. S. uberis was co‐cultured at 4 °C with MAC‐T cell monolayers. Both strains of S. uberis adhered to MAC‐T cells. However, the non‐encapsulated strain of S. uberis adhered better to MAC‐T cells than the encapsulated strain. Preincubation of MAC‐T cells with lipoteichoic acid (LTA) and/or treatment of S. uberis with antibodies directed against the carboxyl‐terminal half of type 24 M protein reduced adherence of both strains of S. uberis to MAC‐T cells. Adherence to ECMP was measured by incubating bis‐carboxyethyl‐carboxyfluorescein acetomethyl ester (BCECF‐AM) labelled S. uberis in 96‐well plates coated with fibronectin, collagen or laminin. Both strains adhered to ECMP, however, the encapsulated strain adhered better to ECMP than the non‐encapsulated strain. Results of this investigation demonstrated that both strains of S. uberis evaluated were capable of adhering to bovine mammary epithelial cells and to ECMP. Adherence of S. uberis to mammary epithelium may be an extremely important mechanism in the establishment and progression of bovine intramammary infections.
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