Turkish Journal of Veterinary & Animal Sciences
DOI
-
Abstract
Circadian variations in serum triiodothyronine (T_3), thyroxine (T_4), free triiodothyronine (fT_3), and free thyroxine (fT_4) levels were investigated in Iranian ewes. For that purpose, blood samples were collected from the jugular veins of 15 adult clinically healthy Iranian nonpregnant uniparous ewes every 6 h (0600, 1200, 1800, and 0000) during 6 days in summer with a mean ambient temperature of 40 °C. Serum T_3, T_4, fT_3, and fT_4 were measured by radioimmunoassay. There were statistically significant differences in thyroid hormone concentrations (T_3, T_4, fT_3, and fT_4) at different hours of the day. The results revealed that serum T_3, T_4, fT_3, and fT_4 levels were highest at 1800 (P < 0.05). Significant 24 h periodicity in the serum levels of T_3, T_4, fT_4 and fT_3 was observed in nonpregnant uniparous Iranian ewes. It is concluded that circadian rhythm was observed in serum thyroid hormones.
Keywords
Circadian rhythm, triiodothyronine, thyroxine, nonpregnant uniparous ewes
First Page
137
Last Page
140
Recommended Citation
NAZIFI, SAEED; SAEB, MAHDI; HASANKHANI, MAHDI; ANSARI-LARI, MARYAM; GHAFARI, NARJES; and HASANSHAHI, FATEMEH (2008) "Circadian Variations of Thyroid Hormone Levels of Nonpregnant Uniparous Fat-tailed Iranian Ewes in Summer," Turkish Journal of Veterinary & Animal Sciences: Vol. 32: No. 2, Article 13. Available at: https://journals.tubitak.gov.tr/veterinary/vol32/iss2/13
