Copper speciation in dairy cattle with different productivity levels

There are almost no studies in the field of speciation of trace elements in the body of farm animals, in particular cattle. In this regard, the purpose of this study was to examine the species composition of copper in dairy cows depending on their productivity level. From the total number of Red Steppe breed cows (n = 90), 2 groups were formed: cows with low-normal milk yield values (n = 17)-group I (low-productive animals, average daily milk yield up to the 25th percentile); cows with high-normal values (n = 23)-group II (highly productive animals, average daily milk yield above the 75th percentile). Regardless of the productivity level, the content of chemical elements in the blood serum was in the range of normal physiological values. However, it was reliably established that highly productive animals had lower potassium levels and higher levels of phosphorus and copper relative to low-producing animals. The results of speciation analysis showed four copper-containing fractions in the blood serum of cows: transcuprein, ceruloplasmin, albumin and low-molecular forms of copper. Copper in the blood serum of cows of the Red Steppe breed, regardless of the level of productivity, is predominantly associated with albumin and ceruloplasmin (up to 90%). The rest of the copper was bound to transcuprein and low-molecular complexes (about 10%). When the level of total copper in the blood serum was up to 900 μg/L (0.9 μg/ml), the albumin fraction predominated over ceruloplasmin, and low-molecular-weight complexes prevailed over transcuprein. However, with an increase in the level of total copper above 900 μg/L (0.9 μg/ml), a shift occurred in the protein fractions; the ceruloplasmin fraction began to predominate over the albumin fraction, and transcuprein over low-molecular-weight complexes. In addition, a significant positive statistically significant association was identified between the total content of copper and ceruloplasmin in the blood with the average daily milk yield (r = 0.47; p < 0.05). The obtained data demonstrate the features of copper redistribution in cows of the Red Steppe breed, which can be used for an expanded assessment of the microelement status of animals, and, possibly, for predicting their productive qualities.