Research Why Regulating an Icelandic's Weight is So Difficult

Regulating an Icelandic horse's weight is almost always a challenge unless they are in full time, intense training. Two studies help us understand why.

In 1982, NANA (a native Alaskan corporation) purchased an Icelandic mare and seven geldings to help with the summer herding of reindeer. NANA is located in Kotzebue, Alaska, which is 30 miles north of the Arctic Circle. Over the years, Alaskans had discovered that maintaining large horses over the winter was too cost prohibitive considering the feed and care that they needed so NANA decided to experiment with Icelandic horses.

Observation by University of Alaska showed that the Icelandics would eat a much wider range of tundra vegetation than other breeds and their energy requirements were 20 % less than other breeds, a fact of which the researchers were initially skeptical. In the summer, the horses needed additional zinc and copper provided through mineralized salt. Other vitamins such as D, B12, and thiamine were believed to be sufficiently provided by year round grazing. Researchers note that food needs to be increased if work load is upped; and pregnant mares also required increased feed.

As another study shows, when you reduce the food to 30% of what they are normally fed (ie, reduce food by 70% which no responsible owner would do), thrifty breeds like Shetlands (and I would imagine Icelandics) go into a state of hypometabolism in which the body metabolism slows down and other physiological changes occur so the pony can maintain its weight. This is a primitive adaptation to enable wild animals to adapt and to survive seasonal variation in the amount of food available. Most domestic horse breeds have lost this ability.

So when you severely reduce the amount of food for Shetlands (and probably Icelandics since they are so closely related), you may be inducing hypometabolism, not putting them on a diet. The study does not mention if the reduced core temperature, lowered activity level, and reduced heart rate has any impact on the comfort level or long term heath of the horse.

No wonder we struggle to keep the weight off our Icelandics.

https://www.horsetalk.co.nz/2012/06/29/shetlands-retain-ancient-temperature-ability-control/#axzz459c2LgZK

Photo from: Icelandic horses on Breiðamerkurjökull in Iceland around 1900. Icelandic and Faroese Photographs of Frederick W.W. Howell, Cornell University Library