부산대학교 도서관

Staphylococcus (S.) aureus is an important pathogen in cheese producing dairy goat farms. The aim of this study was to investigate whether somatic cell count (SCC) and PCR analysis of S. aureus in bulk tank milk (BTM), and/or SCC in udder half milk samples could indicate intramammary infection (IMI) with S. aureus. Milk samples (n = 1042) were collected from lactating udder halves of 521 lactating does from 16 herds in mid to late lactation. From the same herds 29 BTM samples were collected. Udder half samples were cultured on blood agar plates and the SCC was measured by California mastitis test (CMT) and DeLaval cell counter (DCC-SCC). Bulk tank milk samples were analysed by PCR for presence of S. aureus and by DCC-SCC. In 15% of the udder halves bacteria was found and of these 80% had CNS and 8% had S. aureus. Udder halves infected with S. aureus had significantly higher DCC-SCC and CMT than udder halves not infected (P<0.0001) and udder halves infected with CNS (P<0.01) and higher DCC-SCC than udder halves infected with other bacteria (P=0.0004). There was a significantly higher risk for a doe to have S. aureus IMI in at least one udder half if the CMT was high in one udder half and low in one udder half (P=0.04) compared to does with low CMT in both udder halves. Significant associations between BTMSCC, S. aureus positive BTM, or IMI with S. aureus could not be found. However, 6 out of 8 herds with S. aureus IMI were PCR positive for S. aureus at least once. A difference in CMT between milk from udder halves within a doe can be used as an indicator for S. aureus IMI at goat level. On udder half level, milk SCC, measured with DCC or CMT, can be used to detect S. aureus IMI. (C) 2015 Elsevier B.V. All rights reserved.