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The Importance of Iodine

The importance of iodine


The importance of iodine

Nigel Mapstone, Feed Nutritionist Discusses the Importance of Iodine

At the end of April, the Guardian newspaper and the BBC suggested that drinking organic milk during pregnancy might be harmful to the human foetus.

The study was carried out by researchers from the University of Reading and published in the journal, ‘Food Chemistry’. This study compared samples of milk taken from supermarkets during the winter. It found that organic milk contains around a third less iodine than standard milk, regardless of fat content. However, the iodine content in a normal 346ml glass of organic milk was still enough to provide the recommended daily iodine intake.

Although any danger to the human foetus has now been discounted, provided the pregnant mother actually drinks milk, it is important that organic and conventional dairy farmers understand the underlying reasons why the deficiency was found. If milk is low in iodine, it is likely that the animal producing the milk is also deficient. Clinical and subclinical iodine deficiency can have serious effects in herds.

Effects include increased calf mortality (non-specific abortion, stillbirth, weak calves, neonatal calf deaths); calf thyroid enlargement (also in selenium deficiency); retained placenta and infertility (especially suboestrus) in more than 10% of cows and heifers in affected herds; reduced libido in bulls; lower milk yield in cows; ill-thrift in calves and yearlings; reduced herd immunity to infections.

The milk samples in question were taken from supermarkets so the organic samples would, by default, be from cows fed a high proportion of forage. The conventional samples may have contained some milk from low input systems, but bulked up with milk from high concentrate mineralised feed system, so the iodine concentration will on average be higher.

The level of iodine in pasture varies depending on plant species, soil type, fertiliser treatment, climate and season. There is no clear relationship between levels in herbage and rock or soil type. Iodine can be deposited by rainfall, especially when clouds form over seawater, with coastal regions seeing the highest level of pasture iodine. The typical level in pasture grasses is 0.2-0.3mg/kg DM. Improved grassland usually has higher iodine levels than unimproved - a high percentage of pastures in upland Wales are recognised as being low in iodine.

Low iodine content in the soil leads to primary deficiency. Secondary deficiency results from ingestion of the goitrogen thiocyanate found in brassicas and legumes. Selenium is also required for the conversion of iodine in the thyroid and so selenium deficiency may lead to a secondary iodine deficiency.

In conclusion, cattle and sheep on spring grass or stubble turnips fed low levels of mineralised concentrate or without mineral supplementation are most likely to be deficient in iodine.

Recognised methods of iodine supplementation

Mineralised compound feed – all MVF organic dairy compounds have a high iodine inclusion.
Mineral powder added to forage or TMR - MVF can formulate a specifi c mineral to meet your farm needs.
Mineral lick buckets – The Rumigan range of buckets
Mineralised salt licks – Red Mollicks or iodised salt
Trace element bolus – Various available from your local MVF branch.

We recommend you contact your nutritionist or Feed Solutions adviser. Farm Sales Co-ordinators based at all Mole Valley Farmers branches can offer guidance on feeds and trace element boluses.

Organic raw Material Supply

In March 2015 a consignment of Ukrainian organic sunflower to the Netherlands was found to be contaminated. The EU stopped further imports until testing procedures could be improved.

On 15 April the Ukrainian certification body for organic feed materials (EKTO) closed its doors. Therefore, there will be no further exports until new control measures and a new certification body have been set up; this may take some months! There are now only limited volumes of Ukrainian organic materials in UK stores.

Over recent years some 70% of organic raw material imports have been sourced from the Ukraine where the very deep topsoil favours a high yielding organic production. As the Ukrainian farmers only receive a small premium for organic crops they have now dumped their organic feed materials into the conventional market as they are desperate for money. This problem is now affecting the sunflower, rape, peas, maize and wheat market.

The Ukraine produces over 300,000 tonnes of organic feed ingredients, of which almost half is imported to the EU via the Netherlands. The UK imported 70,000 tonnes. The Ukraine supply provides up to 50% UK organic wheat, 75% organic maize,  90% organic sunflower and 90% organic rape.

Shippers are trying to source alternative supplies, but there is no one rushing forward. There are limited supplies of Indian/Chinese sunflower and rape and premiums between £150 and £200/t for a far lower specification material.

In Brussels, the main problem is that there is a complete split in the interpretation of the test results and residue levels. Historically, test results of two decimal points for parts per million have been accepted as a low threshold. But some member states want this to be zero and where found, they want the organic feed/material to be downgraded to conventional. Obviously this is a major issue for the supply chain. The Commission stated  Organic raw material supply that this would take months to resolve, so at  present there are no threshold levels, making shippers very nervous to import and certifiers to give accreditation. Meanwhile, the UK trade bodies and Defra are holding weekly conference calls to keep up to date and are chasing for interim measures in the case of raw material outages.

Mole Valley Feed Solutions is reformulating its organic compounds to spread the raw materials we have till new crop becomes available. This will inevitably increase costs as organic soya is brought in to replace the cheaper proteins. At present, there are no offers of organic rape in any volume and limited supplies of proteins from other sources. Soya is available from China, Kazakhstan  or India, but the supplies are tight as the US is a major importer to feed its growing organic livestock industry.

For all intent and purposes, this is a ‘Force Majeure’ situation. Though these words do not exist in the Ukrainian vocabulary!

Source Details

Nigel Mapstone, Feed Nutritionist

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