IODINE IN MILK BY SUPPLEMENTING FEED - AN ADDITIONAL STRATEGY TO ERASE IODINE DEFICIENCY

Central Europe including Germany and the Czech Republic is an endemic goitrogenic area with persisting iodine deficiency which is the cause of the occurrence of goitre and other disorders. Farm animals are also affected with iodine deficiency, therefore new ways of prophylaxis an d possibilities to increase iodine concentration in cow's milk are bei ng sought. In this study a metabolic efficiency of continuously increa sing iodine supplementation in the form of potassium iodide with a def ined iodine uptake in the ration, productional supplement, and a balan ce supplement was investigated on 25 dairy-cows. A 17-week experiment was divided into 5 cycles (four 3-week cycles and one 5-week cycle) so that the basic ration was supplemented with 0, 20, 60, and 150 mg of iodine per day. Iodine content calculated per I kg of dry matter of th e whole ration was gradually increased from 0.1 mg to 7.6 mg of iodine per 1 kg of dry matter. The results indicate that a gradual iodine su pplementation had a significant effect on increased iodine excretion i n milk. Iodine level in milk reached 128.1 mu g per 1 1 prior the expe riment on a standard ration, however after a iodine supplementation at the.end of the experiment the level rose to 470.0 mu g per 1 1. In th e first week of a 3-week cycle iodine level of 819.0 mu g per 1 1 was found. The experiment further included quality evaluation of milk, fun ctional evaluation of thyroid gland based on the contents of triiodoth yronine (T-3), thyroxine (T-4), and thyrotropic hormone of hypophysis (TSH). No effect of the described model of iodine intake on quality pa rametres of milk (sensual characters, contents of urea, lipid, protein s, lactose, and cell elements count), and the mean concentrations of T -3 (2.87 +/- 0.24 nmol/l) and T-4 (65.29 +/- 7.19 nmol/l) in blood was found. Non-significant variation of TSH was due to other factors than iodine supplementation.