Enzyme-linked immunosorbent assay, single radial immunodiffusion, and indirect methods for the detection of failure of transfer of passive immunity in dairy calves.
BACKGROUND
Confirmatory tests for failure of transfer of passive immunity (FTPI) in dairy calves require direct measurements of the serum immunoglobulin G concentration. Enzyme-linked immunosorbent assay (ELISA) has advantages over single radial immunodiffusion (SRID) in terms of cost and time.


OBJECTIVE
To evaluate the agreement between ELISA and SRID, and to compare the diagnostic performance of ELISA with indirect methods, in the detection of FTPI in calves.


METHODS
One hundred and fifteen dairy calves (aged 0-10 days) from 23 calf-rearing facilities.


METHODS
Prospective, observational study. The agreement between SRID and ELISA was determined by the Bland-Altman method. Fixed bias (SRID - ELISA) was calculated. For comparison of the diagnostic performance of ELISA with indirect methods, sensitivity, specificity, and area under the curve (AUC) of receiver operating characteristic (ROC) curves were calculated at cut-off values of 500 and 1,000 mg/dL.


RESULTS
The agreement between SRID and ELISA was 94%. Fixed bias (SRID - ELISA) was 140 +/- 364 mg/dL. The AUC and sensitivity of ELISA at the cut-off value of 1,000 mg/dL were higher than those of indirect methods (P<.004). The specificity of ELISA at the cut-off value of 1,000 mg/dL was not higher than that of indirect methods, except for serum total protein concentration assay.


CONCLUSIONS
ELISA exhibited good diagnostic performance and good agreement with SRID. ELISA is an adequate method for both screening and confirmatory tests for FTPI in dairy calves at the cut-off value of 500 mg/dL.
Lee
S-H
SH
Department of Clinical Pharmacology and Therapeutics, University of Ulsan College of Medicine, Seoul, Korea.
Jaekal
J
J
Bae
C-S
CS
Chung
B-H
BH
Yun
S-C
SC
Gwak
M-J
MJ
Noh
G-J
GJ
Lee
D-H
DH
D000818:Animals; D000831:Animals, Newborn / Q000276:immunology; D019540:Area Under Curve; D002417:Cattle / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary*; D005260:Female; D007112:Immunity, Maternally-Acquired / Q000276:immunology*; D005779:Immunodiffusion / Q000379:methods / Q000662:veterinary*; D007074:Immunoglobulin G / Q000097:blood*; D011237:Predictive Value of Tests; D012372:ROC Curve; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D007074:Immunoglobulin G