Recent information on iodine deficiency in New Zealand sheep flocks

Authors: Clark RG, Sargison ND, Littlejohn RP, West DM
Publication: New Zealand Veterinary Journal, Volume 46, Issue 6, pp 216-222, Dec 1998
Publisher: Taylor and Francis

Animal type: Livestock, Production animal, Ruminant, Sheep
Subject Terms: Clinical pathology, Diagnostic procedures, Diet/rations/food, Endocrine/autocrine/paracrine, Thyroid, Disease/defect, Trace elements, Metabolic disease, Nutrition/metabolism, Mortality/morbidity, Neonatal, Reproduction, Reproduction - female, Research/development
Article class: Scientific Article

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Abstract: AIMS: To determine the value of pasture iodine, serum thyroxine (T4) and tri-iodothyronine (T3) concentrations and thyroid (g) to body weight (kg) ratios in lambs as criteria to predict and diagnose increased litter size and decreased perinatal mortality in response to iodine supplementation.
METHODS: Results from ten iodine response trials in ewes using an oil-based intramuscular iodine preparation were reviewed along with results from investigations into goitre on five farms in the Manawatu.
RESULTS: In two trials, litter size was increased by 14% and 21% in iodine-treated ewes. In only three of the 10 trials was there a significant reduction in perinatal mortality in iodine-treated ewes.
CONCLUSIONS: Pasture iodine and serum thyroxine (T4) and tri-iodothyronine (T3) concentrations appeared to be unhelpful in predicting the occurrence of increased litter size and reduced perinatal mortality in response to iodine supplementation. New-born lambs from ewes not supplemented with iodine, that had a mean thyroid weight (g) to body weight (kg) ratio of 0.40 g/kg or greater, generally had a significant increase in perinatal mortality compared to lambs from iodine-supplemented ewes.

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