Open AccessEvaluation of Digital and Optical Refractometers for Assessing Failure of Transfer of Passive Immunity in Dairy Calves
Author(s) -
Elsohaby I.,
McClure J.T.,
Keefe G.P.
Publication year - 2015
Publication title -
journal of veterinary internal medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.356
H-Index - 103
eISSN - 1939-1676
pISSN - 0891-6640
DOI - 10.1111/jvim.12560
Subject(s) - refractometer , refractometry , medicine , optics , refractive index , physics
Background Failure of transfer of passive immunity ( FTPI ) is the underlying predisposing risk factor for most early losses in dairy calves. Refractometers, either optical or digital, can be used to assess FTPI as a part of calf health monitoring program on dairy operations. Objectives To evaluate the performance of and differences between digital B rix and optical refractometers for assessing FTPI in dairy calves. Animals Two hundred H olstein calves from 1 to 11 days of age. Methods A cross‐sectional study was designed to measure serum I g G concentration by radial immunodiffusion ( RID ) assay, digital Brix and optical refractometers. The correlation coefficients ( r ) between the 2 refractometers were plotted against each other and against the measured I g G concentration from RID . The S e, S p, and accuracy of digital B rix and optical refractometers for assessing FTPI using previously recommended cut‐offs were calculated. A receiver operating characteristic curve was created and used to identify the optimal cut‐off for this dataset. Results The RID I g G concentration was positively correlated with digital B rix ( r = 0.79) and optical ( r = 0.74) refractometers. The best combination of S e (85.5%), S p (82.8%), and accuracy (83.5%) of digital B rix refractometer was at 8.3% B rix. For optical refractometer, the best combination of S e (80%), S p (80.7%), and accuracy (80.5%) was at 5.5 g/dL. Conclusions and Clinical Importance Both refractometers exhibited utility in assessing FTPI in dairy calves.