title: Innate immunity and carbohydrate metabolism alterations precede occurrence of subclinical mastitis in transition dairy cows.
abstract: BACKGROUND
  This study examined whether activation of innate immunity and alterations of carbohydrate and lipid metabolism precede development of subclinical mastitis (SCM).
  
  
  METHODS
  Blood samples were collected from the coccygeal vein from 100 Holstein dairy cows at -8, -4, disease diagnosis week, and +4 weeks postpartum. Six healthy cows (controls - CON) and six cows that showed clinical signs of SCM were selected for serum analyses. All serum samples were analyzed for acute phase proteins (APP) haptoglobin (Hp) and serum amyloid A (SAA); proinflammatory cytokines including interleukin 1 (IL-1), IL-6, and tumor necrosis factor (TNF) and serum lactate, BHBA, and NEFA concentration. Data of DMI, milk production, and milk composition were recorded and analyzed.
  
  
  RESULTS
  The results showed that cows with SCM had greater concentrations of SAA, TNF (P < 0.01), and lactate before expected day of parturition (P < 0.05) compared to CON cows. Cows with SCM showed greater concentrations of lactate starting at -8 weeks (P < 0.05) and TNF starting at -4 weeks prior to the expected day of parturition (P < 0.01). Interestingly, at -4 weeks, concentrations of IL-1 and Hp were lower in cows with SCM compared to healthy cows (P < 0.01) followed by an increase during the week of disease diagnosis (P < 0.05). Subclinical mastitis was associated with lower DMI, at -4 weeks before calving, milk production (P < 0.05) and increased somatic cell counts (SCC) (P < 0.01).
  
  
  CONCLUSIONS
  Results of this study suggest that SCM is preceded by activated innate immunity and altered carbohydrate metabolism in transition dairy cows. Moreover the results support the idea that Hp, lactate, and SAA, at -8 weeks, and TNF and IL-1 at -4 weeks can be used as early indicators to screen cows during dry off for disease state.
authors.affiliation: Department of Agricultural Food, and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5 Canada.
authors.forename: Elda
authors.initials: E
authors.lastname: Dervishi
authors.affiliation: Department of Agricultural Food, and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5 Canada.
authors.forename: Guanshi
authors.initials: G
authors.lastname: Zhang
authors.affiliation: Department of Agricultural Food, and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5 Canada.
authors.forename: Dagnachew
authors.initials: D
authors.lastname: Hailemariam
authors.affiliation: Department of Agricultural Food, and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5 Canada.
authors.forename: Suzana M
authors.initials: SM
authors.lastname: Dunn
authors.affiliation: Department of Agricultural Food, and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5 Canada.
authors.forename: Burim N
authors.initials: BN
authors.lastname: Ametaj
keywords: Acute phase proteins; Blood metabolites; Cytokines; Dairy cows; Subclinical mastitis; Transition period