title: Evaluation of the use of nonesterified fatty acids and β-hydroxybutyrate concentrations in pooled serum samples for herd-based detection of subclinical ketosis in dairy cows during the first week after parturition.
abstract: OBJECTIVE
  To evaluate the use of nonesterified fatty acids (NEFA) and β-hydroxybutyrate (BHBA) concentrations in pooled serum samples for herd-based detection of subclinical ketosis (SCK) in dairy cows after calving.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  1,100 dairy cows from 110 herds.
  
  
  METHODS
  Blood samples were collected from 10 healthy cows/herd in the first week after parturition. Aliquots of serum were mixed to create a pooled sample. Concentrations of NEFA and BHBA were measured to estimate prevalence of SCK. Pooled sample test results were compared with those obtained for individual samples. Linear regression and receiver-operating characteristic curve analysis were performed; Bland-Altman plots were used to evaluate agreement between methods.
  
  
  RESULTS
  Overall prevalence of SCK was 30.7%, 19.3%, and 13.6%, as determined by use of BHBA threshold concentrations of 1,000, 1,200, and 1,400 μmol/L, respectively. Pooled sample concentrations of NEFA and BHBA were significantly correlated (r = 0.98 and 0.97, respectively) with individual sample means and with the number of cows that had NEFA (R(2) range, 0.81 to 0.84) or BHBA (R(2) range, 0.65 to 0.76) concentrations above predefined thresholds. Pooled sample concentrations of NEFA and BHBA were very accurate to highly accurate for herd-based detection of SCK.
  
  
  CONCLUSIONS
  Analysis of NEFA and BHBA concentrations in pooled serum samples was useful for herd-based detection of SCK. A sample size of 10 cows/herd was deemed adequate for monitoring dairy herds for SCK. Reference criteria specific to pooled samples should be used for this type of herd-based testing.
authors.affiliation: Clinic for Ruminant Health, Faculty of Veterinary Medicine, Freie Universität Berlin, 14163 Berlin, Germany. borchardt_vetmed@hotmail.de
authors.forename: Stefan
authors.initials: S
authors.lastname: Borchardt
authors.forename: Rudolf
authors.initials: R
authors.lastname: Staufenbiel
mesh_terms: D020155:3-Hydroxybutyric Acid / Q000097:blood*; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000097:blood* / Q000175:diagnosis; D003430:Cross-Sectional Studies; D003612:Dairying; D005230:Fatty Acids, Nonesterified / Q000097:blood*; D005260:Female; D007662:Ketosis / Q000097:blood / Q000175:diagnosis / Q000662:veterinary*; D036801:Parturition; D011247:Pregnancy; D013997:Time Factors
chemical_list: D005230:Fatty Acids, Nonesterified; D020155:3-Hydroxybutyric Acid