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Observations on Taste Preferences Part 2

Forage analyses of Cow Parsley and Cleavers bring up surprising results!

We are all for adding diversity to the horses diet but only if it is going to do them good.

Two of the frequently mentioned plants are cleavers and cow parsley. Sue, our UK Representative, picked some of each last spring and sent them away to be analysed.

The results were actually a shock!

Cow Parsley

Fresh cut Cow parsley had a potassium level of 6.77% * CAB (Cation Anion Balance) was 1585 * Cleavers had a potassium level of 7.58% * CAB level 747 *

In both analyses the sugars and crude protein levels were < 5% *Safe horse pasture or forage should be < 2% potassium and the CAB (DCAD) should be < 200


The levels of potassium and the CAB’s in these plants are EXTREMELY HIGH; to the point of being toxic if eaten in large enough quantities.

They are likely this way because they have been growing in the shade (high potassium, low nitrogen & sugars)

Interesting that horses do like to eat them, this goes along with the taste preferences evident in our last post. They go for it not because they ‘know they need it’ or because of ‘sugars’ because there are hardly any in there, but purely because it tastes good to them.

This is another nail in the coffin of the theory that horses ‘know’ what they ‘need’ and will therefore ‘choose’ plants accordingly.

Potassium is one of the most abundant elements in the horse’s forage and if anything they benefit from ingesting less rather than more. The metabolic consequences of a high potassium diet are under-estimated in the horse because adverse effects are secondary. When diet analyses come up with results saying that potassium levels are way more than your horses daily requirement it definitely of concern.

So should you allow your horses to eat these plants?

It comes down to how much the horse eats RELATIVE TO HIS SIZE – obviously a few mouthfuls is unlikely to cause problems but if the horse ate TOO MUCH they could cause serious metabolic problems in any livestock.

How much is too much?

That would depend on:

1. The individual horse’s metabolic fitness/status at the time ie his capacity to cope. For example horses whose metabolism is already compromised because they are ‘grass-affected’ in one way or another, will be far more vulnerable to potential harm. It takes very little of the ‘wrong’ forage to tip these horses over. Laminitis prone equines are an obvious example, head-shakers/flickers are another. Such forage would be risky for pregnant mares especially those close to foaling.

2. What the rest of the horse’s diet consists of – eg if the horse is already out on short or lush green grass, or has alfalfa in his diet (both high potassium forages); allowing him to freely browse on these plants is not advisable.

While a few mouthfuls won’t do any harm, you wouldn’t allow your horse to go to town on it! They are certainly not necessary.

Wild Horses reintroduced to the Pontic Steppes of Eurasia By Yegor Geologist - Own work, CC BY-SA 4.0
Wild Horses reintroduced to the Pontic Steppes of Eurasia By Yegor Geologist - Own work, CC BY-SA 4.0

*NRC Mineral Tolerance of Animals, Second revised edition 2005.

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