The effect of a mixed-ligand cobalt complex on blood parameters in high-yielding Holstein cows

Based on the data obtained during the scientific and economic experiment, it has been proven that replacing cobalt sulfate with a mixed-ligand cobalt complex in high-yielding cows, even in smaller doses, did not significantly affect the biochemical parameters of their blood. However, smaller doses of organic cobalt slightly increased the number of erythrocytes by 1.54–3.39 % and hemoglobin by 0.8–2.94 %, while also reducing the number of leukocytes by 2.31–4.37 %. This indicates the positive effect of organic cobalt on the regulation of hematopoietic processes and the overall physiological state of the animals. The use of a mixed-ligand cobalt complex also positively influenced the protein metabolism in cows. An increase in total protein levels in blood serum by 3.40–5.24 % was recorded, along with an increase in albumin content by 3.65–7.97 % and α-globulins by 2.78–8.33 %. The concentration of γ-globulins was 9.76–17.56 % higher compared to the control group. The increase in the proportion of γ-globulins in total protein can be considered a factor in improving the immune status of lactating cows. The level of volatile fatty acids in the experimental groups also exceeded the control indicators by 0.32–12.50 %, indicating an improvement in microbial digestion processes in the rumen of the cows. The activity of peroxidase and catalase, as well as the content of vitamin B12 in the blood serum, was directly dependent on the level of cobalt in the cows' diet. At the same time, the latter indicators were inversely dependent on the level of organic cobalt in the diet. In the experimental groups, catalase activity in the blood increased by 34.15–89.33 % compared to the control group, where it was 3.28 U H2O2. The content of vitamin B12 in the blood serum of the control group animals was within 0.66 µg/L, while in the 2nd, 3rd, 4th, and 5th experimental groups, this indicator was higher by 9.09 %, 19.7 %, 31.82 %, and 4.55 %, respectively, which underscores the organic relationship between cobalt levels in the diet and the concentration of vitamin B12 in the cows' blood.