The associations of management parameters, herd
characteristics, and individual cow factors with bovine
mastitis have been subject of many studies. The present
study aimed to evaluate the association between milk
composition parameters, including fat, protein, lactose,
urea, and specific immunoglobulin levels, at the time
of experimental bacterial inoculation of the mammary
gland and subsequent shedding dynamics of Staphylococcus
aureus. Sixty-eight cows were experimentally
infected with S. aureus and closely monitored for 3 wk.
Mixed model analyses were used to determine the influence
of management and herd characteristics (farm
and experimental group), individual cow factors (days in
milk, milk yield, and quarter position), and a challengerelated
parameter (inoculation dose) in combination
with either the milk components fat, protein, lactose and
urea, or the S. aureus-specific antibody isotype titers at
the time of bacterial inoculation, on the number of S.
aureus reisolated from milk after inoculation. A positive
association was observed between the milk fat percentage
and the number of S. aureus reisolated from quarter
milk, and a negative relationship between the S. aureusspecific
IgG1 titer in milk and the number of S. aureus.
These findings should be considered in the development
of a vaccine against S. aureus-induced bovine mastitis.