A Comparative Study of Colorimetric and Atomic Absorption Methods for Measuring Copper in sera of Sheep

Abstract Copper deficiency is a significant issue in the livestock industry, particularly in small ruminants. This study compared two common methods for measuring serum copper: atomic absorption spectrometry (AAS) and colorimetry. Blood samples were collected from the jugular vein of 150 healthy female sheep, all over two years old with at least one calving history. Sera were stored at -30°C before analysis. Copper levels were measured using both AAS and colorimetry, and ceruloplasmin levels were assessed in 35 samples using a commercial kit. Results showed that copper levels measured by colorimetry (0.97 ± 0.15 ppm) were slightly higher than those by AAS (0.75 ± 0.21 ppm), with no significant correlation between the methods (r = -0.157, P = 0.06). Ceruloplasmin averaged 4.52 ± 1.85 mg/dL. Its correlation with copper measured by AAS was weak, inverse, and non-significant (r = -0.23, P = 0.6), while a moderate, direct, and significant correlation was observed with colorimetric values (r = 0.47, P = 0.001). Given the ease of use, lower cost, and stronger correlation with ceruloplasmin, colorimetry may serve as a reliable alternative to AAS for evaluating serum copper levels in sheep.