Quantity, variability and correlation of sex and thyroid hormones in sheep of Romanov breed with biochemical, physicochemical and cytogenetic parameters

A comprehensive assessment of the physiological state of animals should include a study of hormone levels and their correlations with different hematological, biochemical, physicochemical and cytogenetic parameters. Hormonal status is an important integral indicator reflecting the general condition of the organism and the adaptive capabilities of animals. The average values, variability and reference intervals of sex and thyroid hormones in sheep of Romanov breed in Western Siberia were determined. No significant correlations were found between the levels of the studied hormones in the blood serum. Average and high correlations of various directions were found between the hormone levels with some biochemical, physicochemical and cytogenetic parameters. Thus, triiodothyronine correlated positively with the number of leukocytes (r=0.441) and urea (r=0.509), but negatively with conjugated bilirubin (r=–0.558). Thyroid hormones were largely associated with biochemical parameters. Sex hormones were associated in many cases with the level of heavy metals in some organs of sheep. Thus, estradiol was positively associated with the copper content in the heart (r=0.463) and liver (r=0.439), but negatively with the lead level in the lungs (r=–0.499). Negative correlations were found between the thyroid hormone content and some indices of somatic chromosomal instability. Thus, the level of triiodothyronine negatively correlated with the frequency of chromosome aberrations (r=–0.527), and thyroxine with the frequency of chromosome breaks (r=–0.639).