The objectives of the present study were to investigate the change in the number of
viable pathogens during preservation of milk obtained from cows with subclinical mastitis
and the association between the decreasing ratio of viable bacteria during preservation
and the somatic cell count (SCC) and the values of lingual antimicrobial peptide (LAP),
lactoferrin (LF) and lactoperoxidase (LPO). After preservation of milk at room temperature
for 0, 0.5, 1, 2, 3, 4 and 5 hr, the bacterial colonies in the milk were counted to
determine the number of colony forming units (CFUs). Fresh skim milk was used to determine
the values of LAP, LPO and LF. Bacteria were not detected in 19.4% of milk samples, and
this percentage increased up to 30% after 5 hr of preservation. The number of
Staphylococcus aureus and Streptococcus uberis in milk
did not change significantly during the 5-hr incubation, whereas significant decreases
were observed in the number of coliforms, coagulase-negative staphylococci, yeasts and
Corynebacterium bovis. High SCC significantly decreased CFUs of
S. aureus and yeast after preservation of milk for 4 to 5 hr. High LF
concentration in milk was associated with decrease in CFU of S. aureus
during 4-hr preservation. These results suggest that the viable counts of some pathogens
in milk decreased during preservation at room temperature after collection, which may be
attributed to the leukocytes and antimicrobial components present in milk.
The present study was undertaken to clarify the factors that reduce the viable pathogen
count in milk collected from the udders of subclinical mastitic cows during preservation.
Milk was centrifuged to divide somatic cells (cellular components, precipitates) and
antimicrobial peptides (soluble components, supernatants without fat layer); each fraction
was cultured with bacteria, and the number of viable bacteria was assessed prior to and
after culture. In 28.8% of milk samples, we noted no viable bacteria immediately after
collection; this value increased significantly after a 5-hr incubation of milk with
cellular components but not with soluble components (48.1 and 28.8%, respectively). After
culture with cellular components, the numbers of bacteria (excluding
Staphylococcus aureus and Streptococcus uberis) and
yeast decreased dramatically, although the differences were not statistically significant.
After cultivation with soluble components, only yeasts showed a tendency toward decreased
mean viability, whereas the mean bacterial counts of S. uberis and
T. pyogenes tended to increase after 5-hr preservation with soluble
components. These results suggest that most pathogens in high somatic cell count (SCC)
milk decreased during preservation at 15 to 25°C, due to both the cellular components and
antimicrobial components in the milk. Particularly, the cellular components more potently
reduced bacterial counts during preservation.
We determined the clinical signs and blood ionized calcium (iCa) levels in dairy cows with peracute coliform mastitis (PCM). The clinical scores at the onset of the disease (day 0) and on day and subsequent days were significantly (P <0.01) higher than those of healthy cows. We found a positive correlation (r = 0.894, P <0.01) between iCa and total calcium (TCa) concentrations in the blood of healthy cows ; however there was no correlation from day 0 to day 3 in the blood of PCM cows. Multiple regression analysis revealed that the concentration of iCa was correlated with rectal temperature, hematocrit value, platelet count, and albumin level of PCM cows at the onset of disease (r =-0.804, r = 0.6576, r = 0.6182, r=0.284, P <0.01, respectively). There was no correlation between the TCa concentration and these parameters for PCM cows at day 0. Low blood iCa concentration at day 0 for PCM cows was related to symptoms of septic shock involving hypothermia, activation of the blood coagulation system, and dehydration.
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