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

Christopher D. Calloway Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211.
present address is the Department of Veterinary Clinical Sciences, College of Veterinary Medicine, University of Illinois, Urbana, IL 61802.

Search for other papers by Christopher D. Calloway in
Current site
Google Scholar
PubMed
Close
 DVM
,
Jeff W. Tyler Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211.

Search for other papers by Jeff W. Tyler in
Current site
Google Scholar
PubMed
Close
 DVM, PhD, DACVIM
,
Ronald K. Tessman Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211.

Search for other papers by Ronald K. Tessman in
Current site
Google Scholar
PubMed
Close
 DVM
,
Douglas Hostetler Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211.

Search for other papers by Douglas Hostetler in
Current site
Google Scholar
PubMed
Close
 DVM, MS
, and
Julie Holle Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211.

Search for other papers by Julie Holle in
Current site
Google Scholar
PubMed
Close

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 endpoint 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. (J Am Vet Med Assoc 2002;221:1605–1608)

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 endpoint 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. (J Am Vet Med Assoc 2002;221:1605–1608)

All Time Past Year Past 30 Days
Abstract Views 433 0 0
Full Text Views 1322 1029 70
PDF Downloads 467 216 21
Advertisement