The objective of the work presented in habilitation thesis was to investigate hormonal status of high-yielding dairy cows under normal condition and ketosis, to develop informative diagnostic tests and effective therapy. Complex investigation of plasma levels of hormones (insulin, cortisol, thyroid stimulating hormone, triiodothyronine, thyroxine, prolactin, oxytocin, calcitonin, parathormone) in high yielding dairy cows under normal condition and ketosis. Conducted experimental research of hormonal and metabolic status allowed to investigate strain of metabolic compensatory mechanisms during critical physiological periods (3 weeks before calving, 2 weeks after calving, peak of lactation, end of lactation) in high yielding dairy cows. This provided the means to establish pathways of reallocation of metabolic energy during development of lactation dominant. In particular, it was revealed that the plasma content of prolactin, oxytocin, cortisol, thyroid stimulating hormone and parathormone was elevated in high-yielding dairy cows during initial weeks of lactation. At the same time the levels of thyroid hormones (triiodothyronine, thyroxine, calcitonin) and insulin were low. Activity of pituitary and thyroid gland is increased at the peak and at the end of lactation. Hormonal status of high yielding dairy cows with ketosis was investigated. In these animals decreased level of insulin, triiodothyronine, thyroxin, calcitonin and elevated levels of cortisol, thyroid stimulating hormone and parathormone were revealed. Further development was given to examination of amino acid composition of plasma in healthy and ketotic cows. Increase in activity of gluconeogenesis leads to disbalance in plasma amino acids content. In particular, level of glycogenic amino acids (alanine, arginine, asparagine, valine, histidine, glycine, glutamine, methionine, proline, serine, threonine, cysteine) is lowered, and the level of ketogenic amino acids (leucine, lysine, tyrosine, tryptophan, phenylalanine) is increase; abovementioned changes cause an elevation of glycogenic to ketogenic amino acids ratio. Concentration of ketogenic, aromatic and sulphur-containing amino acids is increased and the content of glycogenic and branched amino acids is lowered in plasma of affected with ketosis cows. Moreover, there was a significant increase in the plasma level of markers of contractile proteins catabolism (3-methylhistidine, index 3-methylhistidin/creatinine) in cows with ketosis. Also, changes in plasma phospholipid composition was noted in ketotic cows. In particular, relative level of phosphatidylethanolamine was lowered and the concentration of phosphatidylserine, phosphatidylcholine increased on the background of lowering of the plasma level of total phospholipids. Development of ketosis in dairy cows causes substantial changes in functional state of liver, consequently synthesis of serum proteins suffers (hypoalbuminemia in 61% of cows), amino acids metabolism is violated (100% of cows), as well as lipids (100% of cows) and calcium (92% of cows) metabolism. Conducted research allowed to suggest that in part of high-yielding dairy cows ketosis is accompanied with other pathologies, in particular thyroid gland hypofunction and secondary osteodystrophy. Obtained results served as a basis for development of informative diagnostic tests and effective therapy for ketosis of dairy cows. Informative value of new diagnostic tests used for metabolic disorders in dairy cows was determined, in particular, plasma level of 3-methylhistidine, lactate-to-pyruvate ratio, 3-methylhistidine to creatinine ratio, the ratio of esterified to total cholesterol, glycogenic to ketogenic amino acids, essential to nonessential amino acids, etc. For the first time complex therapeutic agent "Remivital" was used in high-yielding dairy cows, affected with ketosis with concomitant liver pathology, hypofunction of thyroid gland and secondary osteodystrophy. After administration of "Remivital" in combination with propylene glycol to ketotic cows, normalization of functional state and structure of liver was observed, which manifested through elevation of albumins content, albumin/globulin ratio, cholesterol esterification, phospholipid content and lowering of the level of total bilirubin, aromatic and sulphur containing amino acids, the activity of marker hepatic enzymes. Administration of "Remivital" allows to normalize metabolism more effectively in comparison with conventional regimens. Signs of hypoglycemia and hypoinsulinemia were registered in three out of eight cows, treated with conventional scheme, five cows in that group had hyperproteinemia and increased activity of hepatic enzymes. Key words: cows, ketosis, insulin, cortisol, triiodothyronine, thyroxine, thyroid stimulating hormone, calcitonin, parathormone, oxytocin, prolactin, pathogenesis, treatment, agent "Remivital".
