Posted by Malcolm Green on 3rd Jun 2021

Are your conditioning cubes making your horse batty


Our horses need fuel to carry out their work, maintain their bodies and keep warm. This fuel (calories or in the modern jargon Mega Joules) can be provided in different forms:

  • Sugars and starches - which are rightly going out of fashion because in horses they lead to colic, ulcers, insulin resistance and laminitis
  • Protein - any of this that is provided in excess of the horses requirement for maintaining and repairing muscles and other organs will also be used as a fuel source. If you overdo this expect the by products of protein metabolism to increase the ammonia levels in your stable bedding
  • Fibre - that is digested by beneficial bacteria in the hindgut, converted into fatty acids and is the primary form energy that horses are designed to utilise
  • Fats and oils - that contain about two and a half times more calories per kilogram than starches but this is the sort of energy that is released slowly and is generally regarded as "non-heating"

These days plenty of performance cubes or conditioning cubes are available with much lower starch levels that previously - this is a good thing.

But still there are a large number of horses struggling with the typical conditioning cube? What is it about some of them that makes them ‘heating’? On a regular basis, the finger will simply be pointed at a specific brand ‘Oh my horse can’t eat such and such brand of cubes, he goes bananas – but he’s fine on this brand!’ why is that? What’s the key difference between one brand and another?

From our experience and speaking to a vast number of customers (and even non-customers!) there seem to be three main causes of horses struggling with some conditioning cubes these are; moderate to high starch levels1 , a level of supplementary magnesium that doesn’t suit the particular horse and a number of herbal ingredients3 (mostly added as flavourings) that hit the same receptor in the brain as diazepam (Valium).

Over the past few years we have honed in on magnesium. In our experience horses don't overdose on the magnesium in grass and hay (mostly in the chlorophyll molecule) but they seem to struggle with artificial magnesium sources like Mag oxide, sulphate, chloride or modern chelated magnesium. These are the forms commonly added to feeds and supplements.

For a while we thought there was an "ideal" level of supplementary magnesium. That seemed to be about 0.8 grams a day - we used to call that "Mid-Mag" though it was a lot lower than many conditioning feeds that supply 6-10 grams a day. The only science published on the topic (Jess Dodd3 ) suggests that 2.5 grams probably and 10 grams definitely does have a comparable effect to a dose of Acepromazine (veterinary sedative). With added magnesium having the ability to sedate and impair, and some horses responding negatively to this, it’s no surprise (to us!) that when a conditioning cube that contains a reasonably high amount of added magnesium is introduced into the diet – behaviour can be compromised.

If your horse's behaviour seems compromised by it feed the odds are, the horse is coping just fine with the increased amount of calories in the diet. More likely it’s actually the extra magnesium provided by the cubes which is causing a range of poor behaviour2 such as napping, stressing, explosive when under pressure, spooky or fizziness…the list goes on!

We’re not saying all conditioning cubes are the spawn of Satan – there will certainly be plenty of people reading this thinking ‘well my horse is totally fine on his 2 scoops of cubes a day’ and there may well be a number of reasons for that (one of them being that potentially the brand you’re using is very low in added magnesium and another that your horse tolerates magnesium well enough). Read more about magnesium here:

It is more recently that we have turned our attention to GABA agonist herbs. These appear in some formulated feeds but are becoming more common in chaffs and fibre products where they are used as flavourings. Read more about these herbs here. Our problem is simple - they interfere with our brain supporting nutritional package:

There will certainly be a number of people who are either scratching their heads as to what to feed their horse to fuel its summer workload or to help it maintain condition over the winter! Others will be debating as to whether or not they’re in need of a calmer for the next few months…more so, there are also plenty of owners out there who simply ‘put up’ with poor behaviour, not realising life could perhaps be a little easier if a few changes in the diet were made!

If you’re considering a 'calmer' – do feel free to give us a buzz for a chat, you may not be in need of a calmer at all. What’s more, simply introducing a magnesium calmer or a herbal sedative to a high magnesium diet will more than likely have no effect (hello wasted pennies), or even make the situation worse (not ideal).

There shouldn’t be a complete feeling of terror when more calories are introduced into a horse’s diet. Providing it’s in the appropriate amount of work, behaviour shouldn’t be compromised. The important bit is choosing exactly how you’re going to get those calories in there!

What would we suggest?

Anything that doesn’t contain ‘bumph’ essentially! Now we’re not going to pretend we don’t offer such feeds (-cough- MORE Condition -cough-), but in general the likes of grass nuts, beet pulps (unmolassed) or oil-based products are a good route to go down. Easy, simple ways to increase your horse’s Digestible Energy intake without the added magnesium and not putting behaviour/performance at risk.

Our own conditioning products are designed to compliment our CORE balancers and they comprise:

  • MORE Fibre (DE 13.5 MJ) - this really is a conditioning fibre because of its high energy level that comes almost exclusively from "super-fibres" and oils. It is the foundation product that we like to get most horses onto because of the digestive benefits of the fibres it contains. Many horses need as little as a mug full a day (200g) so a 20kg bag lasts up to 100 days.
  • MORE Condition or MORE Work (DE 23MJ) - If the horse needs more than a couple of mugfuls of MORE Fibre then start adding MORE Condition or MORE Work. These two products are almost identical. Your horse decides if it needs to convert the energy they contain into fat cover (condition) or movement and work (fuel). Based on sunflower seeds and linseed (to balance the omega oils these products also contain the antioxidants required for a higher oil diet.
  • MORE Muscle (DE 15MJ) - not technically a conditioning feed because it is aimed more at building muscle than putting on fat cover. This high protein product also contains ingredients selected to support muscle function and repair.
  • MORE Chaff (DE 8MJ) - this is also not a conditioning product. Its primary function is to extend the meal size and slow down chewing and consumption. It is a straight straw chaff with some added molasses for palatability which we find is far better than adding GABA agonist herbs.

Our CORE&MORE feed system is designed to put you in control of the feed needs of your horses. Talk to us about converting your horse to this unique yet simple approach. And help your horse look as spectacular as this (Woodlander Sir Gorgeous):


1. The effects of a high-starch or high-fibre diet on equine reactivity and handling behaviour. L Bulmer et al. Applied Anim Behaviour Science April 2015 165:95-102

2. We have no scientific reference for this but do monitor and carefully log the magnesium levels of the diets of horses before they start on our behaviour supplements and where they settle when the customer reports being happy at the end of “fine tuning”. This database now contains many thousands of records and we tend to look at the last 500 horses to get a picture of how our current advice is working. Last time we looked at horses where we were supplying all the supplementary magnesium to the diet through CORE&MORE the final outcomes were:

97% best on no added magnesium

3% best on between 0.1 and 0.4 grams of added magnesium a day

3. Again we have no scientific references for this but we have monitored customer feedback and clearly some horses respond poorly to these herbal ingredients.

4. JA Dodd et al, Magnesium Aspartate Supplementation and Reaction Speed Response in Horses, Abstract / Journal of Equine Veterinary Science 35 (2015) 401-402

Fancy a chat or want to know more?

Feel free to drop us an email on or call 01453 836974.

Our team of advisers are experts in low magnesium feeding and are more than happy to help you get the most of your horse.

It all starts with the diet!

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