[Comparative radioisotope study of the thyroid in various species of agricultural animals]

Radioisotope functional investigations of the thyroid gland were carried out with weaned lambs and pigs. The 131I captation capacity of the thyroid gland was studied to characterize the inorganic phase of iodine exchange. The evaluation of the hormone producing function of the thyroid gland required the determination of the level of the protein-bound 131I (PB 131I), T3-binding capacity of the thyroxin-binding globulin (TBG) and the ratio of the T3-binding capacity of TBG and the free thyroxin (T4) calculated as the FT-4 index. Established was the species peculiarity of the 131I captation capacity of the thyroid gland in weaned lambs and pigs in the early phases of investigation. At the 2nd hour the percent captation was calculated as 7.2 +/- 0.8 and 1.11 +/- 0.21 per cent, respectively. The values of PB 131I, T3-binding capacity of TBG and FT-4 of pigs varied within the limits of 1.20 +/- 0.05 per cent, 0.605 +/- 0.012, and 0.976 +/- 0.015 and of weaned lambs they were 0.954 +/- 0.009 per cent, 0.912 +/- 0.017 and 0.890 +/- 0.03. The differences in the investigated indices for the two animal species a L = 0.05 were statistically significant.