Iodine in the milk-effects of iodine and rape seed feeds in the cow's diet and consequences for human nutrition

摘要

There is still iodine deficiency in many populations, which justifies efforts to increase the content of this trace element in food such as milk and eggs by fortifying the animal feed with extra iodine. Additionally to the amount of the trace element in the diet the milk-iodine concentration is affected by the occurrence of rape feeds. Former experiments with high and low glucosinolate rapeseed meal (RSM) in dairy cows (Papas et al., 1979) charakterized the glucosinolates as iodine antagonists, i.e. the milk iodine concentration was decreased by RSM feeding. Further dairy cow experiments with rapeseed feeds from 00 varieties either confirmed these findings (Emanuelson et al., 1993) or there was only a tendency of iodine milk concentration decrease and no effect on the total milk iodine amount in the milk amount per day (Jahreis et al.,1995). The present study consisted of three parts. In the first part results of newer German studies of milk iodine concentration are presented. As second part, in a dose response experiment with lactating cows a broad range of iodine supplements was tested quantifying the effect of dietary iodine on the milk iodine concentration. As third part, the effect of a RSM with extremely low glucosinolate content should be tested on the milk iodine concentration.