Microbiological quality and somatic cell count of ewe milk with special reference to staphylococci

Abstract

A total 1502 useful half udders of 762 Churra ewes from eight herds were aseptically sampled in midlactation to study both the bacteriological isolates and the SCC of milk. Corynebacteria, enterococci, micrococci, staphylococci, and streptococci represented 11.2, 2.9, 1.4, 78.9, and 3.1% of all isolates, respectively. Within staphylococci, novobiocin-sensitive species (71.1%) were much more frequently isolated than novobiocin-resistant ones (7.8%). Staphylococcus epidermidis was the most prevalent species (53.2% of the isolates). Log SCC of uninfected half udder milk was 4.86. Isolates of novobiocin-resistant coagulase-negative staphylococci, micrococci, and corynebacteria were associated to low values of log SCC (4.85 to 5.20). In contrast, infection by novobiocin-sensitive coagulase-negative staphylococci, streptococci, and enterococci organisms was related to a sharp inflammatory response with log SCC means between 5.92 and 6.32. The species that showed the highest log SCC were Pasteurella haemolytica (7.62), Streptococcus agalactiae (7.28), and Staphylococcus aureus (6.68). High prevalence of infections by novobiocin-sensitive staphylococci together with high SCC related to such infections show a relevant role of these organisms in ewe mastitis. Consequently, implementation of staphylococcal mastitis control programs would be of great interest in dairy ewe herds to improve microbiological and hygienic quality of milk.