1983
DOI: 10.1079/bjn19830031
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Iodine metabolism and thyroid hormone relationships in growing sheep fed on kale (Brassica oleracea) and ryegrass (Lolium perenne)–clover (Trifolium repens) fresh-forage diets

Abstract: I. Kale (Brassica oleracea) and ryegrass (Lolium perenne)-clover (Trijolium repens) pasture, grown under similar soil conditions, were grazed in the vegetative state by growing lambs of 23.6 kg initial live weight for 24 weeks. The kale and pasture contained respectively 20 and 270pg iodine/kg dry matter (DM). The kale also contained 8 pmol total glucosinolates/g DM and 11.5 g S-methyl-L-cysteine sulphoxide (SMCO)/kg DM, both of which were nondetectable in the pasture diet.2. Intramuscular injections of I (475… Show more

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Cited by 39 publications
(29 citation statements)
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“…While T 4 is the most predominant thyroid hormone in circulation (Piosik et al, 1997), with concentrations increasing in the lamb before parturition and declining rapidly within the first few days of life (Forhead and Fowden, 2014), T 3 is deemed the most biologically active (Choksi et al, 2003;Rose et al, 2007). There is a strong relationship between both total the free thyroid hormone fractions with circulating levels of T 3 arising from the de-iodination of T 4 by a selenium containing enzyme, type 1 iodothyronine 5'-deiodinase (Barry et al, 1983;Camacho et al, 2012). However, in the current study a lower concentration of free T 3 was observed in lambs born to CaIO 3 ewes.…”
Section: Discussionmentioning
confidence: 99%
“…While T 4 is the most predominant thyroid hormone in circulation (Piosik et al, 1997), with concentrations increasing in the lamb before parturition and declining rapidly within the first few days of life (Forhead and Fowden, 2014), T 3 is deemed the most biologically active (Choksi et al, 2003;Rose et al, 2007). There is a strong relationship between both total the free thyroid hormone fractions with circulating levels of T 3 arising from the de-iodination of T 4 by a selenium containing enzyme, type 1 iodothyronine 5'-deiodinase (Barry et al, 1983;Camacho et al, 2012). However, in the current study a lower concentration of free T 3 was observed in lambs born to CaIO 3 ewes.…”
Section: Discussionmentioning
confidence: 99%
“…The I requirements of cattle appear to be less than those for sheep, because the incidence of goitre in lambs is greater than in calves (Sinclair & Andrews 1954). The stems of kale and the bulbs of swedes were very low in I. Kale also contains glucosinolates, which are hydrolysed during chewing and digestion to produce thiocynates, which have goitrogenic properties and reduce the uptake of I by the thyroid (Sinclair & Andrews 1954;Barry et al 1983). Unsupplemented lambs fed kale containing 0.02 mg I kg" 1 DM for 24 weeks showed a marked thyroid enlargement, depletion of thyroid I, and low serum thyroxine (T4) and triiodothyronine (T3) concentrations.…”
Section: Discussionmentioning
confidence: 99%
“…Poor performance of sheep grazing brassica crops has been attributed to antiquality compounds that produce toxic metabolites during rumen fermentation, including glucosinolates, which impair thyroid gland function (Barry et al, 1981;1983), S-methyl cysteine sulfoxide, which causes a hemolytic anemia (Smith, 1980), and nitrate, which may cause sudden death, decreased production, abortion, or low lamb birth weight (Pfister, 1988). The high water content of brassica forage may physically limit feed consumption (Lambert et al, 1987;GuiUard et al, 1988).…”
Section: Introductionmentioning
confidence: 99%