The Irish dairy industry has lost markets in the EU due to the excessive levels of iodine in our milk, according to Teagasc’s Dr. David Gleeson.

Speaking at the Teagasc national milk quality farm walk, hosted by the Power family in Co. Waterford, Gleeson said iodine levels are a concern for the industry.

“We have way too much iodine in our milk,” Gleeson stated.

“A number of years ago when we had a deficiency of iodine, around 30 to 40 years ago, it was suggested that we should have higher levels of iodine [in our feedstuffs],” Gleeson said when explaining how the current issue developed.

And now, he said, there is too much iodine going into cows’ diets.

“About 12mg of iodine per cow per day is a safe bet. It’s 5mg per cow per day in other countries.

“We’re putting in 120mg in a lot of situations. Some of our feeds could contain 30mg/kg of iodine and farmers could be feeding 4kg of that. That’s 120mg per cow per day,” Gleeson said.

He also mentioned how some supplementary magnesium products contain added iodine and can result in iodine intakes of up to 90mg per cow per day.

Sources of iodine such as these have the potential to increase iodine levels above market requirements and this has become a concern in recent times.

To achieve the iodine specifications for milk powder products, which are currently difficult for Irish manufacturers to achieve, the target level in raw milk needs to be 100mg/kg.

A recent survey carried out by Teagasc, found an average iodine level of 109mg/kg in bulk tank milk; with a range of 7-to-1,121mg/kg.

28% of farm supplies had milk iodine levels above the limit of 100mg/kg.

The seasonal milk production in Ireland adds to the problem, as most cows are fed supplementary concentrate containing iodine. Irish farmers also give iodine supplementation with the expectation of reduced calving difficulties, improved calf health, increased cow fertility and improved udder health.

Other products such as boluses and drenches can be of benefit if cows are deficient in some important trace elements. However, these products can elevate milk iodine levels.

Some bolus products can reportedly release iodine levels of up to 54mg/cow/day; while multivitamin drenches, used once-off during the breeding season, can contribute up to 75mg/cow, and mineral licks can add up to 40mg/cow/day.

Cows excrete any surplus iodine into the milk and urine, resulting in increased levels in milk, he said.

“It’s a waste of money. It is not as if you are storing up this cow by giving great back-up of iodine. The iodine only lasts 10 days in a cow’s system,” explained Gleeson.

Gleeson acknowledged the conscious effort made by feed manufacturers to reduce the level of iodine going into feed.

He concluded by saying that farmers need to be aware of the potential iodine sources and to aim to feed only the appropriate daily cow intake of iodine.