title: Validation of a new point-of-care assay for determination of β-carotene concentration in bovine whole blood and plasma.
abstract: BACKGROUND
  β-Carotene is an important precursor of vitamin A, and is associated with bovine fertility. β-Carotene concentrations in plasma are used to optimize β-carotene supplementation in cattle, but measurement requires specialized equipment to separate plasma and extract and measure β-carotene, either using spectrophotometry or high performance liquid chromatography (HPLC).
  
  
  OBJECTIVE
  The objective of this study was to validate a new 2-step point-of-care (POC) assay for measuring β-carotene in whole blood and plasma.
  
  
  METHODS
  β-carotene concentrations in plasma from 166 cows were measured using HPLC and compared with results obtained using a POC assay, the iCheck-iEx-Carotene test kit. Whole blood samples from 23 of these cattle were also evaluated using the POC assay and compared with HPLC-plasma results from the same 23 animals. The POC assay includes an extraction vial (iEx Carotene) and hand-held photometer (iCheck Carotene).
  
  
  RESULTS
  Concentrations of β-carotene in plasma measured using the POC assay ranged from 0.40 to 15.84 mg/L (n = 166). No differences were observed between methods for assay of plasma (mean ± SD; n = 166): HPLC-plasma 4.23 ± 2.35 mg/L; POC-plasma 4.49 ± 2.36 mg/L. Similar good agreement was found when plasma analyzed using HPLC was compared with whole blood analyzed using the POC system (n = 23): HPLC-plasma 3.46 ± 2.12 mg/L; POC-whole blood 3.67 ± 2.29 mg/L.
  
  
  CONCLUSIONS
  Concentrations of β-carotene can be measured in blood and plasma from cattle easily and rapidly using a POC assay, and results are comparable to those obtained by the highly sophisticated HPLC method. Immediate feedback regarding β-carotene deficiency facilitates rapid and appropriate optimization of β-carotene supplementation in feed.
authors.affiliation: Department of Physiology and Pathophysiology, Institute of Nutritional Science, University of Potsdam, Nuthetal, Germany. jraila@uni-potsdam.de
authors.forename: Jens
authors.initials: J
authors.lastname: Raila
authors.forename: Francis
authors.initials: F
authors.lastname: Enjalbert
authors.forename: Ralf
authors.initials: R
authors.lastname: Mothes
authors.forename: Andrea
authors.initials: A
authors.lastname: Hurtienne
authors.forename: Florian J
authors.initials: FJ
authors.lastname: Schweigert
mesh_terms: D000818:Animals; D002417:Cattle / Q000097:blood*; D002851:Chromatography, High Pressure Liquid / Q000662:veterinary; D005260:Female; D019095:Point-of-Care Systems; D015203:Reproducibility of Results; D019207:beta Carotene / Q000097:blood*
chemical_list: D019207:beta Carotene