| Summary: | Mastitis is one of the major causes of economic loss in dairy industry and mainly
caused by a bacterial infection. The objectives of this study were to determine the
molecular prevalence of S. aureus subclinical mastitis and to determine the acute
phase response of haptoglobin (Hp), serum amyloid A (SAA) and o l-acid
glycoprotein (AGP) in serum and milk with relation to somatic cell count (SCC) during
experimentally induced subclinical mastitis in goats. A total of 111 goats were
screened for mastitis using the California Mastitis Test (CMT). Phenotypic
identification of S. aureus was done. The genotypic identification was conducted by
Polymerase Chain Reaction (PCR) to detect the nuc gene. Ten goats were included and
divided into two group of five goats each. 1 ml inoculum containing 1.2 x 108 cfu of S.
aureus was inoculated intracisternally into the mammary gland of five goats. The five
other goats were infused with 1 ml of sterile phosphate- buffered saline to serve as a
control. Serum and milk concentrations ofHp, SAA and AGP were evaluated pre- and
post-inoculation (6, 24, 48 and 72 hours) using ELISA kits. The SCC was measured
by direct microscopic method. The SCC was assessed by direct microscopic method.
The prevalence of S. aureus subclinical mastitis was 42% (8/19). Serum and milk Hp
concentrations increased significantly up to 72 hours compared to the control
(P<0.05). The mean concentration ofHp was significantly higher (P<0.05) in the milk
than the serum. Serum SAA elevated but significantly (P<0.05) at 6 hours only in
infected group. Whereas, the concentration of SAA in milk of infected group was
significantly increased (P<0.05) at 6, 24 and 72 hours than in controls. Serum AGP
concentrations reached peak levels at 48 hours post inoculation. Milk AGP
concentration was significantly increased at 24 hours (P<0.05) and remained
significantly elevated until 72 hours compared to the control. A significant correlation
between milk Hp concentration and SCC was observed (r= 0.56, P< 0.05). There were
no associations between milk SAA and AGP concentrations with SCC. It can be
concluded from this study that Hp is a more sensitive indicator for subclinical mastitis
and maybe useful for early detection S. aureus subclinical mastitis.
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