Find the Iodine!

I recently subscribed to FeedXL and after entering all pertinet data was horrified to realize that my horses were deficient in iodine. I thought I had my bases covered with my vitamin/mineral supplement, but I did not. Most vitamin mineral supplements seem to be designed with the assumption that the horse is recieving an iodized salt supplement and mine were not.

http://www.equinews.com/article/the-nitty-gritty-on-salt

During the winter I worry that they don't consume enough salt due to the cold temps so I add salt to their daily mashes. Salt in the form of sea salt or electrolytes, neither of which has iodine. They do have salt blocks available, one is trace, the other is just plain salt. They seem to show no preference.

The NRC recommendation for iodine for the adult recreational horse (2007) is .35mg/kg of feed. (roughly 3.5mg a day for the 1100# horse, 4.1mg for my Gelin) More is not recommended and the big caveat is that deficiencies show the same symptoms as excess- the only way to tell which is which (without a blood test) is to drag out the calculator and start crunching the numbers.

The average trace mineral salt block containing iodine has 70ppm of iodine, or 70mg/kg. To put it in perspective, if your horse were to meet its NRC recommendation for iodine by consuming the salt block alone, it would go through one 4# block every 36 days. That's a rate of 1.7 ounces a day, which does fall under the recommended salt consumption of the horse of 1-2 ounces a day. ( I'm not sure how long my last block lasted as it was turned into a toy and was smashed to pieces.)

Interestingly enough, iodine, despite having a narrow range of tolerance in the horse, doesn't always make it onto the guaranteed analysis of the feed tag. So if you don't see it listed, but see ingredients such as calcium iodate or potassium iodide, and you're concerned about the overall iodine levels your horse is recieving, call your feed rep and ask. My very quick glance through some commonly fed supplements show that their level of supplementation runs between 1mg to 2mg a day, which by itself isn't enough.

I've ended up putting my horses on a kelp product that provides an iodine analysis. Kelp can range wildly and run exceedingly in regard to iodine content so I wanted to be sure that I wasn't feeding too much.

And thus ends my PSA for the day. Find the iodine. Whether it be in the salt block, supplement, or feed, just make sure it's there!