URINARY IODINE LEVEL AS AN INTAKE INDICAT OR IN DAIRY-COWS

Urinary iodine concentrations were determined in 672 dairy cows of 22 herds. Less than 20 mu g per L, 20 to 50 mu g per L, 50 to 100 mu g pe r L and more than 100 mu g per L were found in 27.5, 24.6, 16.8, and 3 1.3% of the cows, respectively. In terms of the ICCIDD grading, modera te iodine deficiency was recorded in 68.9% and normal iodine intake in 31.3% of the cows. The mean urinary iodine concentrations were 94.8 m u g per L at the peak of the lactation period (it = 300), 82.3 mu g pe r L immediately before drying off (n = 122), 92.5 mu g per L in the co ws fed summer rations (it = 267), and 79.2 mu g per L in those fed win ter rations (n = 405). The differences in mean values were nonsignific ant. Urinary iodine concentrations were examined in the herd LOS in co ws fed iodine-supplemented (LOS E) or nonsupplemented (LOS C) rations. Mean concentrations were 316.2 mu g per L for LOS E (it = 46) and 52. 3 mu g per L for LOS C (it = 41). The difference was highly significan t (P < 0.01). The status of the group LOS C was classified as a medium iodine deficiency. The mean iodine concentrations at the peak of the lactation period and immediately before drying off were also significa ntly higher (P < 0.01) in this group. The supplementation of iodine re sulted in an increase of urinary iodine concentration and, in terms of ICCIDD, the increase of iodine intake to the normal range. The ICCIDD classification scheme was also used in ten selected herds. At least 2 5 cows were examined in each of them. Normal intake and moderate, medi um and serious deficits were found in three, two, one, and four herds, respectively. Special attention should be paid to herds showing highe r grades of iodine deficiency.