Measurement of neonatal equine immunoglobulins for assessment of colostral immunoglobulin transfer: comparison of single radial immunodiffusion with the zinc sulfate turbidity test, serum electrophoresis, refractometry for total serum protein, and the sodium sulfite precipitation test.

This research article discusses the evaluation of four different methods to measure the adequacy of colostral immunoglobulin, or IgG transfer in newborn horses (foals). These methods include: zinc sulfate turbidity test, serum electrophoresis, total serum protein refractometry and sodium sulfite precipitation test. The study found varying degrees of effectiveness and reliability among these methods.

Zinc Sulfate Turbidity Test

• The researchers found that the zinc sulfate turbidity test gave acceptable results in determining the levels of immunoglobulin G (IgG), a key immune system protein transferred from mother to foal via colostrum (first milk).
• A notable limitation was observed in this method: the test resulted in higher than expected values when serum samples were hemolyzed (broken down). As a workaround, the researchers found application of a correction factor for such samples to be helpful.

Serum Electrophoresis

• Serum electrophoresis was assessed as a satisfactory method to estimate IgG content. This method effectively separates proteins based on their size and electrical charge, enabling the specific detection and measurement of IgG levels.

Total Serum Protein Refractometry

• The total serum protein refractometry method was found to have some inconsistencies. This method measures all protein content in the serum and was theorized to indirectly indicate IgG levels.
• However, the research found that total protein values might not reliably indicate IgG content. The researchers observed that following suckling, total protein values decreased in some foals despite an adequate transfer of IgG.

Sodium Sulfite Precipitation Test

• The sodium sulfite precipitation test was found least reliable among the four. This test attempts to measure IgG concentration by inducing a precipitation reaction with sodium sulfite.
• The results of this method were too unpredictable and therefore deemed unreliable for accurately determining neonatal IgG concentration.