title: The impact of high iodine intake on thyroid function in ewes and lambs.
abstract: OBJECTIVE
  The objective of the study was to assess the metabolic risk of excessive dietary iodine intake in ewes and neonatal lambs.
  
  
  METHODS
  Pregnant Šumava ewes received an experimental diet containing 3.1 mg iodine per kg of dietary dry matter in Group A (control, n=13, 6 ewes and 7 lambs) and 5.1 mg iodine per kg of dietary dry matter in Group B (experimental, n=12, 6 ewes, 6 lambs) for eight months. Iodine was administered to ewes as calcium iodate. TSH in blood serum; TT3, TT4, fT3, and fT4 in blood plasma were examined in both groups of ewes and lambs to assess the risks of iodine intake above the permitted limit, as it applies to thyroid gland activity.
  
  
  RESULTS
  Group B ewes showed a significant increase in TSH and TT4 only on day 1 after parturition. The highest values of TT4, TT3, and fT3 in lambs were recorded on day 1 after birth. The lowest values of fT3 and fT4 in lambs were measured on day 60 after birth with no differences observed between the groups. In lambs of Group B the lower concentration of TSH until day 3 after birth was followed by a significant increase from day 10 after birth.
  
  
  CONCLUSIONS
  Our results indicate a risk of postnatal hypothyroidism among lambs from pregnant and lactating ewes having a high iodine intake.
authors.affiliation: Department of Veterinary Disciplines and Quality of Products, Faculty of Agriculture, University of South Bohemia in České Budějovice, Czech Republic.
authors.forename: Hana
authors.initials: H
authors.lastname: Dušová
authors.forename: Jan
authors.initials: J
authors.lastname: Trávníček
authors.forename: Martin
authors.initials: M
authors.lastname: Svoboda
authors.forename: Tomáš
authors.initials: T
authors.lastname: Baňoch
authors.forename: Vlasta
authors.initials: V
authors.lastname: Kroupová
authors.forename: Zdeněk
authors.initials: Z
authors.lastname: Peksa
authors.forename: Roman
authors.initials: R
authors.lastname: Konečný
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D005260:Female; D007037:Hypothyroidism / Q000097:blood / Q000139:chemically induced*; D007455:Iodine / Q000633:toxicity*; D007774:Lactation; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000097:blood / Q000139:chemically induced*; D011897:Random Allocation; D012756:Sheep; D013961:Thyroid Gland / Q000187:drug effects* / Q000502:physiology*; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D014131:Trace Elements / Q000633:toxicity; D014284:Triiodothyronine / Q000097:blood
chemical_list: D014131:Trace Elements; D014284:Triiodothyronine; D013972:Thyrotropin; D007455:Iodine; D013974:Thyroxine