Quantitation of bovine immunoglobulins: comparison of single radial immunodiffusion, zinc sulfate turbidity, serum electrophoresis, and refractometer methods.

Laboratory methods designed to quantitate serum immunoglobulin were evaluated: single radial immunodiffusion, zinc sulfate turbidity, and serum electrophoresis. Estimation of immunoglobulin concentration in neonatle calves, using total protein measurements, was also evaluated. Single radial immunodiffusion proved useful for quantitation when either class or subclass information was needed. Zinc sulfate turbidity measurements gave accurate results for total immunoglobulin except when hemolysis was present in the sample. A correction factor for hemoglobin that will minimize errors resulting from hemolysis was presented. Serum electrophoresis was also found to be an accurate quantitation method. Large errors were encountered in attempting to estimate immunoglobulin on the basis of total protein.