In this study, 15 merino lambs which were at the same age and similar body weight were used. The animals were divided into 5 groups as Control, Group 1-A. Group 1-B. Group 2-A and Group 2-B. During the first 3.5 month of the experiment, hypothyroidism was induced in the animals except control ones by administration of thiourea. Then, thiourea administration was lasted and potassium iodide (KI) was given to the animals in the Group 1 -B and Group 2-B for 3.5 month.

In the animals which were given thiourea, the mean red blood cell (RBC) and white blood cell (WBC), haemoglobin amound (Hb). hematocrit values (PVC), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH'), mean corpuscular haemoglobin concentration (MCHC) and lymphocytes proportion decreased (7.80x 10⁶/mm³, 4.42x10³/mm³, 7.73 gr/dl, 23.37%, 29.97 µ³, 9.91 pgr. 33.07 % and 60.98% respectively.) However, the values of erytrocyte sedimentation rate (ESR) at 1st, 2nd, 24th hours, neutrophils and basophiles proportions increased (9.65 mm, 21.37 mm and 94.15 mm, 34.23% and 1.72% respectively).

The mean of RBC. WBC. Hb, PVC, MCV. MCH. MCHC. the values of ESR at 1st. 2nd and 24th hours, lymphocytes, neutrophils and basophiles proportions in the animals those were given Kl were found to be 9.98X10/mm³, 5.33/10³/mm³, 10.26 gr/dl. 30.37%. 30.42µ³, 10.28 pgr. 33.79%, 5.94 mm, 16.37 mm. 83.91 mm. 68.50%, 27.48% and 0.75% respectively. On the other hand, in the lambs not given KI, the same values were determined to be 7.90x10⁶/mm³, 4.63x10³/mm³, 7.91 gr/dl. 27.07%, 30.46 µ³ 10.01 pgr. 32.85%. 7.75 mm. 21.05 mm, 92.83 mm. 63.25%, 32.77% and 1.12% respectively.