Creating horse diets with no added magnesium

Written by Malcolm Green, Technical Director, EquiFeast

Magnesium is an essential nutrient for horses, but the enthusiasm with which it is added to horse feeds defies all the science – you will find links to the science from this article. A horse’s Recommended Daily Allowance (RDA) of magnesium can depend on a range of factors. We have summarised these below:

Weight of mature horse in work

Light work (grams per day)

Moderate work

(grams per day)

Heavy work

(grams per day)

Very Heavy Work

(grams per day)

200kg

3.8

4.6

6.0

6.0

400kg

7.6

9.2

12

12

550kg

9.5

11.5

15

15

900kg

11.4

13.8

18

18

If this table does not apply to your horse, further information can be found in Nutrient Requirement of the Horses, 6th Edition, published by the National Research Council, 2007.

Grass, Lucerne and grass hay almost always contain excess of the recommended amount of magnesium for horses whatever their work load.

There are a number of reasons why we believe that the vast majority of horses do better with no added magnesium in their diet. For more information you can access our articles page here.

In this article, Malcolm Green describes how to create a diet with little or no added magnesium in an Australian market.

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Formulated feed options

From what I can gather the only Australian made formulated feed I can find that doesn’t have added magnesium (there may be others but I haven’t yet come across these) is the Running Cool Range from Jenco in Queensland. For some there is a trade-off using these products and this is that they have a relatively high grain, therefore higher starch content. If your horse does well on higher starch levels that is fine. But high starch can be linked to behaviour issues and higher risks of digestive problems.

Making your own diet from “straights”

The only real benefit of formulated feeds is that they contain supplementary vitamins, minerals and sometimes other key nutrients. It is these premixes that nearly always contain magnesium. They may also contain other minerals generally not needed and possibly counter-productive in Australia such as iron and manganese.

Formulated feeds are designed to be fed at a certain rate – often 3-4 kgs a day for a 500kg horse. Feed less and you under-supplement, feed more and you over-supplement. In the UK this has led to a dramatic increase in the use of “feed balancers”. These may take the form of a “feed” that is fed at 250-500 grams per day. Or a supplement that may be in the region of 20-50 grams per day.

These balancers enable you to make up your own diet from pasture, hay (various options) and various other ingredients we will discuss below.

At EquiFeast Australia, our main feed balancer is called Essential Daily Care. It contains no added magnesium, iron or manganese. Essential Daily Care is also available combined with other products:

  • BREAK FREE Elite (also contains chelated calcium for horses on oxalate pastures and was primarily designed following requests for a comprehensive balancer by Campdrafters)
  • BREAK FREE Essentials Lick (chelated calcium and a half dose of Essential Daily Care for extensively managed horses).
  • WINNINGEDGE (contains our chelated calcium along with a package of joint support and is designed for hard working performance or competition horses or those with behavioural or mobility issues)

So what can we make the rest of the diet up with?

Our primary objective is to turn your pasture and grass hays into good horse feed. So unless your horse has a problem with these feeds, they will make the foundation of the diet. It is important to mention here that horses are not designed to eat the sort of rich pastures we have developed for dairy cattle or the exotic oxalate grasses found in many parts of Australia. If your pasture is rich in ryegrass, clover and even Lucerne, then you may need to be sourcing some low carbohydrate, high fibre hay to dilute it with.

Hays from grasses like Teff and Rhodes are probably the safest you can get but good native grasses are also excellent.

Lucerne is a hay that people either love or hate. Generally it is intensively produced so can be very high protein and potassium. For most horses it is fine as a supplementary feed (though probably not if the pasture is rich in ryegrass).

Oaten Hay will normally have a lot of the oat grain left on it. That makes it higher in starch. But oats have been a traditional feed for horses for centuries and there is evidence that, compared to other cereal grains, it is much safer and indeed may have some physiological benefits.

For more concentrated fibre sources consider beet pulp, which is now being imported from the UK, and Copra. Both contain what are becoming known as “super fibres” which are more digestible than grass fibre but also appear to boost the digestibility of the fibre in pasture and hay. So they provide a double whammy. A few people report their horses going a bit loopy on copra so test it out gently.

Sunflower seeds are also high in slow release energy as well as protein and make excellent components of the diet.

Another protein boosting option is from pulses. I’m not a great fan of soya (quite starchy and too many phyto-oestrogens) but lupins claim to have a much better non-starch (but still carbohydrate) energy component. They are readily available – especially in WA.

The feeds above offer a broad range of fibre, energy and protein options enabling horse owners to adjust their diet whether their objective is to build condition or muscle or just provide energy and protein to maintain horses for work.

They also provide plenty of low starch, high fibre options to help manage horses with EMS, PSSM or at risk of laminitis, ulcers, colic etc.

Summary

Formulating a diet using a variety of different “straights” supplemented with a balancer (like EquiFeast’s Essential Daily Care) will provide all the options you need to formulate a feeding routine suitable for your horse.

If you need further help you can use a nutritionist.

Other articles that you may find relevant:

https://equifeast-australia.com/the-myths-about-magnesium-horse-calmers/

https://equifeast-australia.com/calming-and-sedation/

https://equifeast-australia.com/the-future-of-the-horse-calmer/