Groups: (1) ryegrass (control) without iodine; (2) ryegrass (control) with signal dose of 390 mg iodine; (3) radish without iodine; (4) radish with signal dose of 390 mg iodine; (5) rape without iodine; (6) rape with signal dose of 390 mg iodineProcedures: thyroid hormone (T3, T4) response to a thyroid releasingfactor (TRF) challenge in ewes and incidence of goiter in newborn lambs was determined Time: 9 weeks. Here, TG is linked to goiter.