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prime lucerne hay

Whether horses are OK when Lucerne is part of their diet really depends on

  •  Where they live, what species of grass they are already grazing, what stage of growth it is at and what fertilisers have been applied.

  • Whether they are showing signs of ‘increased excitability’? 

Lucerne is most likely to cause problems when it is fed ON TOP OF vegetative COOL season grasses (Those that grow in cooler temperate climates, like rye-grass).
Averagely more people in Queensland for instance, can feed lucerne with no issues, quite likely because their grasses are warm season grasses.

It is about balance. That is precisely what we are doing by taking lucerne out of problem horse’s diets. Achieving balance is just as much about lowering some things as it is about adding some things in.


If a horses diet already has a very high potassium:sodium ratio because of the grass, we don’t want to make it worse by adding to their load.

Of course horses whose own self-regulating mechanisms (which work constantly to maintain the correct ratios of crucial minerals) successfully instruct the kidneys to excrete the excess and conserve what is in short supply all are fine on their own without any help from us.

However after spending the best years of our riding lives

  • battling mysterious, often dangerous issues 

  • selling horses for the wrong reasons, (even sending some to the hunt club for dog-tucker!)

  • spending literally thousands of dollars on professional help

  • never-ending saddle-fitting sessions

  • wasting money on lessons because the ‘horse was not right’

  • spending a lot of time trying to ‘fix’ many problems by applying good horsemanship and ‘working through’ issues, all this time not knowing a thing about diet and never having anyone suggest that this could be the culprit...

Finally we reallised that ‘being mindful of potassium intake’ and feeding more salt would have made the biggest difference! Since then we have really enjoyed our horses!


Of course it is not just about potassium and salt, the horse has to achieve the correct ratios between many different minerals. Electrolyte levels and ratios are particularly important because LIFE depends on them and high potassium diets make it difficult for the horse to keep calcium and magnesium levels right.

The philosophy behind our diet recommendations is to lower potassium intake down to normal levels (horses in their natural habitat are not exposed to chronic potassium over-load of vegetative, often fertilized grasses and legumes 24/7 365 days a year).

Hence anything that adds to this load is logically the first to be eliminated.


Some horses also need the vegetative grass eliminated temporarily as well until they are back to normal and their adrenal glands have had a rest. Simultaneously, we increase the other electrolytes starting with the addition of salt, GrazeEzy & where necessary the AlleviateC/SOS.

This simple adjustment to diet provides immediate relief for many ‘Grass Affected’ horses who suffer terribly, make no mistake. Especially when they are misdiagnosed and ‘sent to a trainer’ who doesn’t get it either!.

Therefore if your horse is NOT consuming vegetative cool season grasses all year round (as is the case in many parts of Australia) and is not exhibiting signs of ‘increased excitability’, lucerne can be a useful source of nutrients including calcium and protein.

The reason it should only be a small proportion of their total forage is that Lucerne is HIGH nutrient density, especially first cuts, and horses need LOW nutrient density for the other 90% of their basic forage.

They are meant to derive a LITTLE bit of nutrition out of a LOT of mouthfuls (they eat 16-18 hours a day). High nutrient density all day is TOO MUCH.

If you have never had the experience of the frighteningly dangerous, 'fire-breathing dragon', completely 'off their trolley', reactiveness of a horse affected by very high potassium load – understandably you won’t believe us and you are very fortunate. Come walk a mile in our shoes.

We reiterate – fill out the Health Checklist. If your horse ticks any of the boxes under ‘Increased Excitability’ and ‘Dangerous Signs’, eliminate all lucerne (Alfalfa) and lucerne based products and check salt intake.

For the same reasons, we do not recommend feeding lucerne to laminitic horses.
The advantage of its lower NSC content (than grass), is overwhelmed by its high potassium and crude protein.

Lucerne flowers

Lucerne flowers

Lucerne affected horse reacting

The Least Known, Most Important Fact You Need to Know...


It is a widely known fact that lucerne is high in calcium and low in phosphorous. This is why the ‘old-timers’ always fed oats when they fed lucerne because oats, being comparatively high in phosphorous, would tend to correct this imbalance.

It is also a widely known fact that lucerne is a good source of protein and can therefore be useful for feeding broodmares, growing horses and horses in intense work. However, grass in growth mode can also be high in protein so a person has to be careful not to feed too much.

Not so widely known is the most important fact that lucerne is high in potassium and extremely low in sodium.

As with other forages there is virtually none in the above ground portion of the plant. Potassium levels average between 2.4 – 3.2% while sodium levels are only 0.01- 0.02%.

Apparently this IS generally known in the farming community and whenever lucerne is fed out, stock are also fed sodium (as salt) The trouble is nobody told the horse people!

There is a lot of information out there regarding the benefits of feeding lucerne to horses but not one mention of this crucial piece of information.

This, plus the high crude protein, is why a lot of people have observed that lucerne ‘sends their horse nuts’! 

Most horses are already consuming an overload of potassium from whatever green grass they are on, then when you add more potassium-rich forage it becomes over-whelming.

Yes the horse does excrete excess in urine and manure but, as a good analogy, ‘it is like ‘trying to empty a swimming-pool while the hose is running in flat-out at the other end’.

Adding potassium-rich lucerne, molasses, kelp, protein meals and many herbs to their already high pasture grass intake has a cumulative effect and puts a constant stress on the horse’s system to frantically excrete potassium at the same time conserving sodium. It is not long before you see the outward signs.

Lucerne CAN be a beneficial addition to the diet of pregnant & lactating mares, growing horses, elderly horses with bad dentition (as hay or chaffage – not chaff) and horses not already on vegetative cool season grasses and clover.

Lucerne, being very dark green in colour, is also high in ‘fluorescing’ pigments which can cause photosensitization (the oozy sores of mud-fever & ‘sun-burn) so it is best eliminated from the diet of horses prone to or suffering from this condition.

Being a legume (like clover) it also contains hormonally active compounds called phyto-estrogens which can affect cycling and breeding.

Lucerne (otherwise known as alfalfa) is a legume not a grass and due to its high nutrient density and digestibility it should only comprise approximately 1/10 of your horses total forage ration. It is the first thing to remove, whenever horses become ‘grass-affected’ in any way.

If your horse is doing just fine on Lucerne don’t change a thing but if he has any of the signs of ‘increased excitability’ (See Health Checklist) swap it out for grassy hay and non lucerne chaffs. 

Mylan very reactive
Mylan much calmer after correcting feed
Mylan competing

Before we came along, this horse’s diet consisted of vegetative rye grass and clover, plus lucerne and processed feeds containing lucerne. He had become dangerous to do anything with. Of course floating (which had previously been absolutely no problem, he was a show horse and had been floated extensively) had become a major issue made worse by someone doing up the back bar before he was ready. By the way, when we first met him, his urine pH was very high. (9 - 10)

The ‘fix’ for him included eliminating the lucerne and removing him from the grass (this is the fastest way to drop potassium intake down to a more normal level), replacing this with plain grass hay (no rye or clover). We had to wait until the diet changes took effect, before we could even attempt to overcome his floating phobias. As a matter of interest, by this time his urine pH had come down to 7-8.

His demeanor went from ‘belligerent’ and uncooperative (1st pic) to being willing to try (2nd pic). Mylan successfully competing once again. (see jumping pic)

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