title: Brix refractometry in serum as a measure of failure of passive transfer compared to measured immunoglobulin G and total protein by refractometry in serum from dairy calves.
abstract: A series of trials were conducted to evaluate Brix refractometry (Brix %) for the assessment of failure of passive transfer (FPT) in dairy calves compared to: (1) serum IgG (reference standard) when measured by radial immunodiffusion (RID) or a turbidometric immunoassay (TIA), and (2) serum total protein refractometry (STP). For the serum samples tested with TIA, STP, and Brix % (n = 310; Holstein calves), the median concentrations were 21.3 g/L IgG, 58 g/L STP, and 9.2%, respectively. For the serum samples tested with RID, STP and Brix % (n = 112; Jersey calves), the mean concentrations were 38 g/L IgG, 68 g/L STP, and 10.2%, respectively. For samples tested with only Brix % and STP (n = 265; Holstein calves), median STP and Brix % were 50 g/L STP and 8.5%, respectively. Correlations between Brix % and RID, and between Brix % and TIA were equal (r = 0.79, respectively). Brix % and STP were positively correlated (r = 0.99). Brix % estimated serum IgG concentrations determined by TIA and RID (r(2) = 0.63, 0.62, respectively). When FPT was defined as serum IgG < 10 g/L, Brix % ≤ 8.5% showed optimal sensitivity (100%) and specificity (89.2%) to predict FPT. At the same IgG cut-point, an STP value of ≤ 52 g/L showed a similar sensitivity (100%) and specificity (80.4%) to predict FPT. Brix refractometry predicted successful transfer of passive immunity in dairy calves, but further evaluation as a diagnostic tool for the diagnosis of FPT is warranted.
authors.affiliation: Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853.
authors.forename: D
authors.initials: D
authors.lastname: Hernandez
authors.affiliation: Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853.
authors.forename: D V
authors.initials: DV
authors.lastname: Nydam
authors.affiliation: Department of Population Medicine, University of Minnesota, St. Paul, MN 55108.
authors.forename: S M
authors.initials: SM
authors.lastname: Godden
authors.affiliation: Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853.
authors.forename: L S
authors.initials: LS
authors.lastname: Bristol
authors.affiliation: Department of Population Medicine, University of Minnesota, St. Paul, MN 55108.
authors.forename: A
authors.initials: A
authors.lastname: Kryzer
authors.affiliation: Department of Population Medicine, University of Minnesota, St. Paul, MN 55108.
authors.forename: J
authors.initials: J
authors.lastname: Ranum
authors.affiliation: Department of Biomedical and Diagnostic Sciences, University of Tennessee, Knoxville, TN 37996. Electronic address: dschaefe@etk.edu.
authors.forename: D
authors.initials: D
authors.lastname: Schaefer
mesh_terms: D000818:Animals; D001798:Blood Proteins / Q000032:analysis; D002417:Cattle; D007112:Immunity, Maternally-Acquired; D007118:Immunoassay / Q000379:methods / Q000662:veterinary*; D005779:Immunodiffusion / Q000379:methods / Q000662:veterinary; D007074:Immunoglobulin G / Q000097:blood*; D009391:Nephelometry and Turbidimetry / Q000379:methods / Q000662:veterinary*; D012031:Refractometry / Q000379:methods / Q000662:veterinary*; D012680:Sensitivity and Specificity
chemical_list: D001798:Blood Proteins; D007074:Immunoglobulin G
keywords: Brix refractometer; Calf; Failure of passive transfer; Immunoglobulin; Serum total protein