Measurement of bovine (<i>Bos taurus</i>) serum albumin by different methods and the comparison of protein fractions determined by capillary zone electrophoresis and agarose gel electrophoresis

Serum albumin measurement is an important parameter routinely evaluated in clinical biochemistry within the livestock industry. It plays a crucial role in assessing the nutritional and health status of animals, as well as in aiding the diagnosis of various pathological conditions as a complementary tool. Several laboratory methods are available for albumin measurement; however, some methods have been documented to overestimate the concentration of serum albumin <i>versus</i> the proposed gold standard of serum protein electrophoresis. The primary aim of the study was to analyze the agreement between albumin measurement in bovine serum samples by the capillary zone electrophoresis (CZE), agarose gel electrophoresis (AGE), bromocresol green (BCG), and purple (BCP) methods. In addition, AGE and CZE methods were also compared for quantitation of globulin fractions. Lastly, reference intervals were established using all methods using the American Society for Veterinary Clinical Pathology (ASVCP) guidelines. Serum samples from 55 clinically normal Brangus cattle (5 ± 1.5 years old) were examined by the four methods. For the albumin method comparison, all methods were significantly correlated (<i>r</i> = 0.55-0.91, <i>p</i> < 0.0001) and the bias between methods ranged from 0.01-0.22 g/dL. For AGE and CZE methods, all protein fractions were significantly correlated (<i>r</i> = 0.85-0.91, <i>p</i> < 0.0001) except for the alpha 1 fraction (<i>r</i> = 0.21, <i>p</i> = 0.12). Five fractions were quantitated using AGE method: albumin, alpha 1, alpha 2, beta, and gamma globulins. For the CZE method, six fractions were resolved with the sub fractionation of beta 1 and beta 2 globulin fractions. The evaluated methods showed good agreement in determining albumin levels in cattle. Although CZE offers higher resolution, it requires careful interpretation and precise definition of fractions. Therefore, methodological choice and consideration of analyzer-specific reference intervals are essential for accurate results.