title: Evaluation of on-farm tools for colostrum quality measurement.
abstract: The objectives of this study were to determine the immunoglobulin G (IgG) content of colostrum on Alberta dairy farms and to determine which on-farm tool, the colostrometer or the Brix refractometer, was more highly correlated with IgG content as determined by radial immunodiffusion (RID). Colostrum samples (n=569) were collected between February and July 2012 from 13 commercial dairy farms in central Alberta, with herds ranging in size from 60 to 300 lactating cows. Immunoglobulin G content was determined directly by RID and indirectly by a colostrometer (specific gravity) and Brix refractometer (total solids). The Spearman correlation was used for the colostrometer and Brix refractometer data. According to RID analysis, 29.1% of the colostrum samples contained <50 mg/mL IgG. Concentrations ranged from 8.3 to 128.6 mg/mL IgG, with a median of 65.1 mg/mL. Third or greater parity cows had higher colostral IgG content (69.5±1.98 mg/mL) than second parity (59.80±2.06 mg/mL) or first parity (62.2±1.73 mg/mL) cows. The colostrometer data were more highly correlated with RID results (r=0.77) than were the Brix refractometer data (r=0.64). Specificity and sensitivity were determined for the colostrometer and Brix refractometer compared with a cut-point of 50 mg/mL IgG as determined by RID. The highest combined value for sensitivity and specificity occurred at 80 mg/mL for the colostrometer (84.1 and 77.0%, respectively) and 23% Brix (65.7 and 82.8%, respectively). This study indicates that although the colostrometer data are better correlated with true IgG values, the user-friendly Brix refractometer is a more specific tool to detect colostrum of adequate quality.
authors.affiliation: Department of Production Animal Health, University of Calgary, Calgary, AB, Canada T2N 4N1.
authors.forename: A L
authors.initials: AL
authors.lastname: Bartier
authors.affiliation: Department of Production Animal Health, University of Calgary, Calgary, AB, Canada T2N 4N1.
authors.forename: M C
authors.initials: MC
authors.lastname: Windeyer
authors.affiliation: Department of Production Animal Health, University of Calgary, Calgary, AB, Canada T2N 4N1. Electronic address: ldoepel@ucalgary.ca.
authors.forename: L
authors.initials: L
authors.lastname: Doepel
mesh_terms: D000416:Alberta; D000818:Animals; D001826:Body Fluids / Q000737:chemistry; D002417:Cattle; D003126:Colostrum / Q000276:immunology*; D003612:Dairying / Q000295:instrumentation*; D005260:Female; D005779:Immunodiffusion / Q000662:veterinary; D007074:Immunoglobulin G / Q000032:analysis*; D007774:Lactation; D011247:Pregnancy; D012031:Refractometry / Q000295:instrumentation / Q000379:methods; D012680:Sensitivity and Specificity
chemical_list: D007074:Immunoglobulin G
keywords: Brix refractometer; colostrometer; colostrum; immunoglobulin G; radial immunodiffusion