Всероссийский научно-исследовательский институт физиологии, биохимии и питания животных – филиал Федерального государственного бюджетного научного учреждения «Федеральный научный центр животноводства – ВИЖ имени академика Л.К. Эрнста»
ABSTRACT. Achieving a certain level of macronutrients in the blood of productive animals is necessary both for maintaining their health and for the normal passage of the stages of the reproductive cycle. The purpose of the experiment was to investigate the concentration of macro minerals (sodium-Na, potassium-K, calcium-Ca, inorganic phosphorus-IP, and magnesium-Mg) in the blood of cows before first calving and in certain postpartum periods and to determine the possibility of using the level of these macro elements to control the conditions that are necessary for the resumption of normal ovulatory cycles and the fertilization of cows with a decrease of the interval from calving to fertilization. The data on the concentration of macronutrients in the blood of first calving cows before fertilization presented in this study were obtained under conditions that are characterized by the presence of optimal levels of total protein, albumin, total cholesterol, and high-density lipoprotein cholesterol. Cows were observed from 9 months of pregnancy to 145 days after calving. The serum concentrations of Na, K, Ca, IP and Mg were determined by colorimetric methods. The obtained results indicate the statistically significant variability of the concentration of Na, Ca, IP and Mg in the blood serum of primiparous cows in luteal or follicular phases of normal and infertile estrous cycles, with the achievement of levels, which were determined in these animals before calving at the end of the normal cycle before fertilization. At the end of a normal cycle, a significant decrease in the concentration of K (P<0.01) in cows was found in comparison with its level in these animals before calving or in a luteal phase of the ovulatory cycle.