Abstract

The main objective of this study was to investigate whether the alpha-lactalbumin (alpha-LA) content; of bulk milk is related with sortie known inflammatory markers and milk quality traits. An additional objective was to study whether combining alpha-LA, haptoglobin (Hp), and serum amyloid A (SAA) in an acute phase index (API) could be useful as an alternative marker for bulk milk quality. For the dairy industry, it is of great importance to receive high quality bulk milk for manufacture of liquid milk and dairy products. The somatic cell count (SCC) is currently used as an indirect marker for bulk milk quality, but because it is somewhat; insensitive and unspecific, interest exists in alternative markers. Bulk milk samples were analyzed for alpha-LA, SCC, polymorphonuclear leukocyte count, Hp. SAA, fat, lactose, total protein and casein contents, casein number, protein composition, proteolysis, and coagulating properties. No significant differences were found in SCC, polymorphonuclear leukocyte count, Hp, or SAA between milk samples containing low, medium, or high concentrations of alpha-LA. Differences between alpha-LA groups were, however, found in some milk quality traits because high alpha-LA concentration was related to low concentrations of alpha(s1)-, alpha(s2)-, and beta-caseins and high concentrations of lactose and beta-lactoglobulin. A high API was related to low lactose content and casein number. Samples with high SCC contained less casein and had a lower casein number than milk with a low SCC, and proteolysis was significantly higher in high SCC milk than in low SCC milk. Neither alpha-LA nor API proved to be a better marker than SCC for the quality traits investigated, and alpha-LA was not; considered to be a useful inflammatory marker in bulk milk.

Keywords

bulk milk quality; somatic cell count; alpha-lactalbumin; acute phase protein

Published in

Journal of Dairy Science
2010, volume: 93, number: 10, pages: 4577-4581
Publisher: ELSEVIER SCIENCE INC

Authors' information