Short communication: Repeatability of differential goat bulk milk culture and associations with somatic cell count, total bacterial count, and standard plate count

• Published in: Journal of dairy science 2010-06, Vol.93 (6), p.2569-2573
• Main Authors: Koop, G., Dik, N., Nielen, M., Lipman, L.J.A.
• Format: Article
• Language: English
• Subjects: Animal productions; Animals; bacterial contamination; bacterial culture; Biological and medical sciences; bulk milk; Cell Count; cell culture; dairy goat; Dairy Products - microbiology; Dairy Products - standards; Dairying - methods; Enterobacteriaceae; Female; food contamination; Food Handling; Food industries; Fundamental and applied biological sciences. Psychology; goat milk; Goats; Milk - cytology; Milk - microbiology; Milk - standards; milk analysis; Milk and cheese industries. Ice creams; milk composition; milk quality; plate count; repeatability; Reproducibility of Results; somatic cell count; Staphylococcus aureus; Terrestrial animal productions; total bacterial count; Vertebrates
• ISSN: 0022-0302; 1525-3198
• DOI: 10.3168/jds.2009-2705

The aims of this study were to assess how different bacterial groups in bulk milk are related to bulk milk somatic cell count (SCC), bulk milk total bacterial count (TBC), and bulk milk standard plate count (SPC) and to measure the repeatability of bulk milk culturing. On 53 Dutch dairy goat farms, 3 bulk milk samples were collected at intervals of 2 wk. The samples were cultured for SPC, coliform count, and staphylococcal count and for the presence of Staphylococcus aureus. Furthermore, SCC (Fossomatic 5000, Foss, Hillerød, Denmark) and TBC (BactoScan FC 150, Foss) were measured. Staphylococcal count was correlated to SCC (r=0.40), TBC (r=0.51), and SPC (r=0.53). Coliform count was correlated to TBC (r=0.33), but not to any of the other variables. Staphylococcus aureus did not correlate to SCC. The contribution of the staphylococcal count to the SPC was 31%, whereas the coliform count comprised only 1% of the SPC. The agreement of the repeated measurements was low. This study indicates that staphylococci in goat bulk milk are related to SCC and make a significant contribution to SPC. Because of the high variation in bacterial counts, repeated sampling is necessary to draw valid conclusions from bulk milk culturing.