Iodine is converted into the essential thyroid hormones with the thyroid gland. A severe deficiency of iodine causes this gland to swell producing a “goitre”.
Recently it has become recognised that low or marginal iodine nutrition of goats is a significant problem in the southern and mountain districts of Victoria.
Iodine deficiency is endemic to the high rainfall districts of Victoria, and similar deficiencies occur along the Great Dividing Range throughout Eastern Australia. Goats seem to have a higher requirement for iodine than other livestock.
Iodine deficiency is only a problem in newborn kids. Adult goats appear able to tolerate seasonal deficits in iodine supply by using reserves stored in the thyroid gland. This reserve is not available to the developing foetus.
Thyroid hormones are essential for growth and development of the foetus, particularly the brain, lungs, heart and hair follicles, and contribute especially to survival of the newborn kid. Iodine deficiency makes newborn kids very susceptible to cold, wet weather and mortalities may be very high.
Recent research at the Attwood Veterinary Research Laboratory has demonstrated that iodine nutrition of sheep and cattle has a marked seasonal cycle in Victoria. Intake of iodine from pasture is lowest in late winter when the requirements of pregnant animals are at a peak.
Thus it has become a standard recommendation that pregnant does grazing in high rainfall areas receive a. drench of supplementary iodine once or, in some cases twice, during the last two months of their pregnancy. Treatment of affected kids with iodine or thyroxine tablets is rarely useful and it is far more effective to ensure adequate iodine nutrition of the foetus.
Kid with an Iodine Deficiency
Drenches: The drench is made up by dissolving 28 gm of potassium iodide in one litre of water.
Each doe should receive 10 ml. Iodine is highly volatile and it is important to mix the drench just before use.
lodised salt licks and feed supplements containing iodine are not recommended in most situations because some goats always avoid licks and it is impossible to accurately gauge intake with these systems.
Drenching is cheap and accurate and can even be combined with some worm drenches, although it is wise to check this with the manufacturer.
Injections: lodised oil injections have been used to prevent iodine deficiency in New Zealand quite successfully. The product is not registered for use in Australia.
Iodine deficiency may also be induced by goitrogens - substances within the feed which inhibit the utilization of dietary iodine. Goitrogens have been detected in some legumes and forage crops, but are considered unlikely to be a significant cause of goitre.
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