Comparison of refractometers and test endpoints in the measurement of serum protein concentration to assess passive transfer status in calves

Christopher D. Calloway, Jeff W. Tyler, Ronald K. Tessman, Douglas Hostetler, Julie Holle

Research output: Contribution to journalArticle

85 Scopus citations

Abstract

Objective - To evaluate 3 refractometers for detection of failure of passive transfer (FPT) of immunity in calves, and assess the effect of refractometric test endpoints on sensitivity, specificity, and proportion of calves classified correctly with regard to passive transfer status. Design - Prospective study. Animals-90 calves. Procedure - Blood samples were obtained from calves that were < 10 days old. Serum IgG concentration was determined by use of a radial immunodiffusion assay. Accuracy of 3 refractometers in the prediction of serum IgG concentration was determined by use of standard epidemiologic methods and a linear regression model. Results - At a serum protein concentration test end-point of 5.2 g/dL, sensitivity of each refractometer was 0.89 or 0.93, and specificity ranged from 0.80 to 0.91. For all refractometers, serum protein concentration test endpoints of 5.0 or 5.2 g/dL resulted in sensitivity > 0.80, specificity > 0.80, and proportion of calves classified correctly > 0.85. Serum protein concentrations equivalent to 1,000 mg of IgG/dL of serum were 4.9, 4.8, and 5.1 g/dL for the 3 refractometers. Conclusions and Clinical Relevance - The refractometers, including a nontemperature-compensating instrument, performed similarly in detection of FPT. Serum protein concentration test endpoints of 5.0 and 5.2 g/dL yielded accurate results in the assessment of adequacy of passive transfer; lower or higher test endpoints misclassified larger numbers of calves.

Original languageEnglish (US)
Pages (from-to)1605-1608
Number of pages4
JournalJournal of the American Veterinary Medical Association
Volume221
Issue number11
DOIs
StatePublished - Dec 1 2002

ASJC Scopus subject areas

  • veterinary(all)

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