In a trial with 50 fattcning pigs (20 kg initial body wcight), thc cffcct of untreated rapcseed rneal (RSM)(14X rnmol glucosinolatcs and agluconcs pcr kg dry matter) on thc thyroid was compared with RSM trcakd with Cu~+(9.5 mmol glucosinolates and agluconcs pcr kg dry matter) and soybcan mcal (SBM). The dicts containing WX) RSM wcrc supplcmentcd with 0.0625-1.0 and the SBM dict (control) with 0,125 mg iodine kg 1 (I). In comparison with SBM fcd controL RSM trcatment with Cu='+ resultcd in a completc normalization of fccd intake and growth. Only untrcated RSM without I supplemcntation depresscd performancc and rcsultcd in symptoms of I dcficiency, but the thyroid and livcr weight wcrc also increased and thc serurn T4 content was significantly rcduccd in animals which werc givcn RSM not supplcmentcd with L but trcated with Cu~ 1• In young pigs (4 wccks) a platcau of thc scnun T~ contcnt was achicved from 0.5 mg I kg 1 of thc RSM diet onwards.

In contrast. when thc conccntration of goitrogcns was rcduccd bv the trcatmcnt with Cu~", thc serurn T~ Ievel was Tncreased significantlv in groups fed with 0.125 mg I kg- 1 diet and more. In oldcr pigs (15 wc~ ks) ncithcr the contcnt of I!. Oitrogcns nor thc I dosagc affcctcd thc serum