Intramammary inoculation of the dairy cow with Staphylococcus aureus and Staphylococcus epidermidis during the nonlactating period

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Abstract
SUMMARY: The susceptibility of nonlactating mammary glands to intramammary inoculation with staphylococci was determined. Susceptibility was determined by inoculation of bacteria through the teat canal directly into the gland sinus. In experiment 1, Staphylococcus aureus (Newbould 305, ATCC 29740) was inoculated into glands at various intervals throughout the nonlactating period. During the first month, 35 of 52 inoculated glands became infected (67.3%). During the month before parturition when 37 glands were inoculated, 36 became infected (97.3%). In experiment 2, Staphylococcus epidermidis (A-44) was inoculated into mammary glands. During the first month of the nonlactating period, 35 glands were inoculated and only 6 glands became infected (17%). During the month before parturition, 36 of 38 inoculated glands became infected (94%). It appears that the mammary gland is susceptible to staphylococcal infection during the nonlactating period, because all glands became infected when they were inoculated during the month before parturition.