Magnesium is hot! Nowadays, when a horse is easily spooked, many people quickly refer to a magnesium deficiency. But what is this based on?
A magnesium deficiency occurs when a horse's diet does not provide the horse with sufficient magnesium. Requirements for horses kept at maintenance are about 0.015 grams per kilogram of bodyweight. For a horse of 400 kilograms, this would result in about 6 grams of magnesium a day.
Very occasionally a magnesium deficiency leads to hypomagnesaemia. Signs of hypomagnesaemia include: loss of appetite, sweating, ataxia, hyperventilation and muscle (including heart) degeneration. Basically, when your horse has a severe magnesium deficiency, you will notice something is wrong and think twice before getting on. A mild deficiency of magnesium, however, can occur more readily. Signs of deficiency are nervousness and muscular tremors, so thinking that a spooky horse has a magnesium deficiency does have some foundation.
Conveniently, roughage usually covers a horse's magnesium requirements by providing about 1.5 grams per kilo. There are, however, several ways in which too little magnesium can be provided to a horse. Firstly, the horse can be fed too little roughage. Secondly, the fed roughage can be of poor quality and not contain sufficient amount of magnesium to cover the horse's needs. Thirdly, requirements vary between horses and exercise increases magnesium demands. Your vet can perform a simple blood test to see whether your horse has a magnesium deficiency.
If your horse has a magnesium deficiency, check the diet. Do you feed your horse sufficient roughage? Feed your horse at least 2 kilograms of roughage per 100 kilograms of bodyweight. Next to providing nutrients, roughage is also key in preventing gastric ulcers and maintaining healthy teeth.Do you already feed sufficient roughage and does your horse still have a magnesium deficiency? Then you can consider feeding a magnesium supplement. The most common magnesium supplements come in the form of magnesium oxide, or magnesium carbonate. Magnesium carbonate is absorbed up to 70%. This means that if you want your horse to absorb a supplemental 7 grams of magnesium, that you should feed it 10 grams of magnesium carbonate. Magnesium oxide is usually a cheaper alternative, however, absorption of magnesium oxide varies (45%-70%).