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.     

Refractometry as a measure of the immunoglobulin status of the newborn dairy calf: comparison with the zinc sulfate turbidity test and single radial immunodiffusion.

Immunoglobulins were quantitated by single radial immunodiffusion in 34 female Holstein-Friesian calves which had been kept with their dams for the first 24 hours of life. The mean immunoglobulin G1 (IgG1) concentration was 1.063 g/dl; IgG2, 0.093 g/dl; IgM, 0.171 g/dl; and IgA, 0.125 g/dl. Both serum total protein as measured by refractometer and zinc sulfate turbidity measured at 498 nm gave good correlations with total protein, which were significant, P less than 0.001. Plasma total protein had a slightly poorer correlation with total immunoglobulins, presumably due to variable fibrinogen content. Plasma total protein gave a better correlation with total immunoglobulins than did any of the immunoglobulin classes individually. Total protein by refractometer underestimated naturally occurring or added immunoglobulins by one-third.     

Effect of temperature on the sodium sulphite precipitation test for assessment of goat serum immunoglobulin

Total serum immunoglobulin concentrations of apparently normal indigenous goats were estimated by a sodium sulphite precipitation test which utilized 3 concentrations of the salt (i.e. 14%, 16%, 18%). A total of 210 goat serum samples comprising five phenotypically different breeds were examined. Immunoglobulin precipitation was greatly influenced by the incubation temperature. Using different concentrations of the sodium sulphite salt solution, serum samples incubated at either 4°C or 38°C consistently gave clear and rapid precipitation reaction in all samples with immunoglobulin concentrations of over 15 mg/ml.

Tests carried out at normal tropical room temperature (28°–30°C) gave inconsistent results and only 52% gave clear precipitation. Neither breed nor sex had any statistically significant effect on either the precipitation rate or the immunoglobulin values (P < 0.05).

It was concluded that this test if performed at either 4°C or 38°C can be used under field conditions to evaluate immune status of neonatal goats in the tropics.