I am often contacted by customers asking what the difference is between Magnesium Oxide and CalMag. I hope this helps:

CalMag is 52% magnesium oxide. It has a gritty, sandy texture as it has not been purified like the magnesium oxide. It is a lot cheaper than magnesium oxide as it doesn't have to go through a lengthy and expensive purifying process. However, it is recommended that you give 4g per 100kg bodyweight, so effectively twice the amount of magnesium oxide. This reflects the fact that it is only 52% magnesium oxide. It costs £2.75 for 900g.

The magnesium oxide I sell is pharmaceutical grade and is 99% pure. As it is a fine powder, it is more easily absorbed than the CalMag. Magnesium oxide is one of the most easily absorbed forms of magnesium, and is £10.49 for 900g. Due to the higher purity, only 2g per 100kg bodyweight is required.

As a third option, I now sell 85% Magnesium oxide, which is a high purity calmag. It cost £4.99 for 900g and should be fed at 3g per 100kg bodyweight, so is a medium-priced option.

They are all a source of magnesium oxide, but vary in their purity, from 52% for the calmag, to 85% magnesium oxide and 99.2% magnesium oxide. This gives a range of costs, with the daily cost being higher, as you use the higher purity.

For example, for a 500kg horse:

Calmag (52%) fed at 4g per 100kg, would be 20g daily, which costs 6.1p daily

85% magnesium oxide fed at 3g per 100kg, would be 15g daily, which costs 8.3p daily

Magnesium oxide (99.2%) fed at 2g per 100kg, would be 10g daily, which costs 11.7p daily

The diet of many horses is low in magnesium due to grazing land been grazed by horses for many years without fertilisers being added. Supplementing magnesium can also help break down fatty deposits.

Magnesum is the main ingredient in most commercial horse calmers. Lack of magnesium can cause nervous and excitable behaviour. In these cases, supplementing magnesium can have a calming effect. However, magnesium is NOT a sedative. horses can show nervous/excitable behaviour for many different reasons including breed, age, exercise, turnout, training, sex, feed, etc. However, IF a lack of magnesium is having an effect on their behaviour, a magnesium supplement can have a dramatic effect.

Magnesium is an important nutrient and can help the growth of strong hooves. It has also been shown to help reduce the build-up of fatty deposits.