EN
The subject of this wprk was the investigation of luteinizing hormone, progesterone, testosterone and total estrogens concentration in the peripheral plasma of 56 gilts with experimentally-induced hypo- and hyperthyroidism and with ovarian cystic degeneration. The blood samples were collected from the cannulated jugular vein at 19-23 days after last natural estrus, 5-10 times daily. The experiments resulted in significant deviations in plasma hormone profile during the periestrous period. The hypothyroid gilts showed a significant increase but hyperthyroid animals a decrease in level of LH accompanied by a significant peak of estrogens on the 22nd day of cycle. The cyst-bearing gilts exhibited a decreased level of LH, an increased concentration of progesterone and a changeable content of estrogens. It may be suggested that abnormalities in hormonal pattern in experimental gilts were caused by derangement of functional interrelationships in the pituitary-thyroid-ovarian axis which influence sex hormone synthesis and release.