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All you need to know about the iodine nutrition of lactating dairy cows


Iodine (I) is an essential trace mineral for all animals and in Teagasc's latest update to dairy farmers it outlined its importance for lactating cows.

It says grazed grass is the most profitable feed available for dairy cows in Ireland, but most of the grass grown provides inadequate iodine to meet lactating cow requirements.

As a result iodine supplementation is necessary.

Teagasc currently recommends that cows receive 12mg supplemental I per day, unless a deficiency is diagnosed on the farm. Care should be taken with supplementing iodine as surplus iodine is excreted in milk and urine.

Milk with excessive iodine is unsuitable for inclusion in infant milk formula.

Recent Teagasc research on commercial dairy farms found that, on average, a pasture-only diet provided 0.25mg I per kg DM (range: 0.04 to 0.98mg I per kg DM).

So for a cow eating 17kg DM, this means an intake of 4.25mg I per day on grass only.

Additional I should be offered so that the cow receives the recommended 12mg of supplemental I per day.

This means if 2kg concentrate is offered to cows, it should be formulated to the 12mg/day I feeding rate, and the inclusion rate should be 6mg/kg.

Offering additional iodine to cows will result in higher milk iodine.

If higher feeding rates or alternative sources of I are used on farm, the inclusion rate in the concentrates fed should be reduced accordingly so that 12mg per cow per day supplemental I is not exceeded.

Check your concentrate docket to see how much iodine you are feeding.

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