Iodine deficiency, iodine requirement and iodine excess of farm animals -Experiments on growing pigs [German]

摘要

Since insufficient iodine intake: is widespread among the German population, farm animals should if possible receive iodine above requirement, thus concentrating the trace element in milk, eggs and possibly meat. Experiments with a total of 29 fattening Figs with grain soy-bean meal diets without iodine supplementation or with increasing supplements up to 1000 mu g iodine/kg diet did not show any effect on growth intensity (gain) and feed efficiency. At and above 125 mu g supplementary iodine/kg diet the thyroid was not or only little hypertrophied and iodine incorporation into thyroglobulin sufficed to sustain serum T-4 concentration The glucosinolates of rape feeds increase iodine requirement. In an experiment with a tc,tal of 36 fattening pigs the thyroid iodine depot was decreased due to rapeseed meal feeding, this in agreement with antithyroid drugs which had been also tested. A thyroid with emptied iodine depot is hardly able to synthesize and release hormone, the serum thyroxine centration showed a drastic decrease. More iodine may compensate for effects of glucosinolates, however, only with not too much of these compounds in the: feted. Excessive iodine dosages (10 mg/kg diet) were compared with supplements in the range of recommendations (100 and 1000 mu g/kg diet) with a total of 120 pigs in three groups of 40 animals each. The dosage of 10 mg iodine/kg diet decreased serum Tg concentration. The enlarged thyroid with double weight had a very high iodine concentration. In comparison with physiological application (100 or 1000 mu g iodine/kg: diet) the thyroid deposited only little iodine in the group with the excessive iodine intake related to consumed iodine quantity. In case of sufficient and excessive iodine supply - industry of compounds feed applies up to 2.5 mg supplementary iodine/kg diet - T-4 and iodine of serum but also thyroid weight cannot serve as markers. This range of usual iodine supply is better characterized by the iodine, depot of the thyroid. As a rule, thyroid weight increase indicates glucosinolate effects, generally those of dietary antithyroid compounds, more seldom it shows extreme and longterm iodine undersupply or iodine excess.