The article presents data on research into the influence of a mineral-vitamin premix on the clinical condition, erythropoiesis and the metabolism (macro- and micro-elemental, vitaminic, proteinaceous, enzymic) of Hucul breed mares in the last trimester of pregnancy. The Marmix premix contains: vitamins – А, D3, Е, В1, В2, В12, pantothenic and ascorbic acids, niacin, biotin; nonorganic compounds of microelements – sulphate of cobalt, copper, zinc, iron, manganese; potassium iodide, sodium selenite; amino acids – lysine, threonine, methionine.The usage of the mineral-vitaminic premix Marmix on pregnant mares during 60 days causes recovery of clinical status, erythropoiesis, raises the level of the cobalt (by 45.9%) and copper (by 2.15 times), normalizes the calcium-phosphorus ratio, raises the phosphorus level in the blood (by 17.7%), raises vitamin А (by 2.5 times) and tocopherol (by 2.02 times), total protein (by 27.7%), decreases the level of urea (by 42.2%), activity of AspAT [aspartate transaminase or aspartate aminotransferase] (by 42.9%) and AlAT [alanine transaminase] (by 44.9%) and alkaline phosphatase (by 43.7%). The research conducted contributes to improvements in the study of the pathogenesis of microelementosis of mares and develops an efficient way of treating and preventing the development of microelementosis among these animals.

Regular physical exercise improves the cardiovascular system function, increases energy metabolism and antioxidant protection, provides greater muscle strength and physical endurance. However, exhaustive physical exercise can cause oxidative stress. During intense physical exercise, erythrocytes become more vulnerable to oxidative damage due to action of active oxygen forms, high concentration of polyunsaturated fatty acids. Physical loading of horses is accompanied by the development of tissue hypoxia, so one needs to study in detail changes of hematopoiesis indices, responsible for providing oxygen to tissues. When monitoring animal health, blood tests will detect a disease in early stages, because blood is a sensitive indicator of metabolic disorders, both of physiological and pathological body conditions. The purpose of present study was to examine changes of some hematopoiesis indicators (RBC, Hb, HCT, MCV, MCH), acid resistance of erythrocytesand population structure in trotting horses due to workloads of 1,600 m trot races (at rest, after race, after 90 min). In total, 20 clinically healthy horses of Orlovska and Russian trotting breeds, aged 2–3 years, were used in the study. The experimental animals included 5 mares, 15 stallions. All horses had active training. The horses were divided into two groups. The first animal group included animals that showed high results (2 min 04 s – 2 min 21 s); the second had trotters that covered the distance with worse time (2 min 28 s – 2 min 41 s). The erythrocyte couint in the leader horses after the loading increased, in the outsider horses it fell. After rest the leader horses’ erythrocytes returned to their original values, in the outsider horses they did not change. The outsider horses’ hemoglobin level after loading was lower than in the leader horses. The leader horses had higher hemoglobin content after rest (by 11.0% as compared with the values before the loading). The outsider horses had lower hemoglobin content. The leader horses hematocrit value increased, in the outsider horses ‒ decreased. The leader horses’ MCV after the loading was reduced, however after rest it recovered. The outsider horses showed MSV increase during the whole study period. The MCH in the leader horses did not change over the entire research period, in the outsider horses – it increased. The animals that showed better results, had an increasing number of “mature” and “old” erythrocytes due to their elimination from the depot. However, the outsider animals had an increasing number of “young” erythrocytes, resistant to hemolysis, but they were not able to provide tissues with needed oxygen.

One of the most important indicators is the assessment of erythroсytopoezis is acid resistance of erythrocytes and their population composition. Changes in these parameters are the most studied in humans, cattle and horses. In small animals, including dogs, the issue is not highlighted enough. Therefore, the study of changes of erytroсytopoezis by using these tests is important. The study erythroсytopoezis parameters was performed in dogs of all ages (1.5–year, 3 – 6 years and 7 and older years of age). It was found that in clinically healthy dogs generall erythroсytopoezis indicators (total number of red blood cells, hemoglobin content, hematocrit value, the index «red» blood – МСН and МСV), regardless of age, did not significantly change. Yet in dogs older than 7 years there were found some changes on the the part of erythroсytopoezis. This was pointed by the changes of the population composition of red blood cells and their acid resistance. In particular, the animals showed an increased number of «old» populations of red blood cells and some changes of their hemolytic resistance. Particularly, the height of the erytrohram peak was 15% higher than in younger animals. The very peak was sharp, indicating the rapid destruction of the «young» red cells and degeneration of their lipid membranes.