The truth about hay protein — why the biggest number isn't the best
Everyone advertises high protein. Here's what those numbers really mean, and what we actually measure.
Scroll through hay adverts and you'll see impressive protein numbers — 12%, 15%, even 18%. It sounds like more is better. But protein is one of the most misunderstood — and most oversold — numbers in horse feed. Here's the honest version.
We'd rather tell you the real, lab-measured value of every batch than chase the biggest number on a label.
Why ‘crude protein’ overstates what your horse gets
The figure on a hay label is crude protein (CP), and it isn't measured directly — it's calculated from the nitrogen content (nitrogen × 6.25). That means it also counts non-protein nitrogen and protein bound up in fibre that the horse can't actually digest. So a big CP number can look better than the protein the horse truly absorbs — two hays with the same CP can deliver very different usable protein.
Why very high grass-hay protein is usually a trade-off
To push grass hay to a high protein number, it has to be cut very young and leafy. But immature grass is also higher in sugar and lower in fibre — exactly what you don't want for a laminitis- or EMS-prone horse, and not ideal fibre for the gut. The forages that are genuinely high in protein (15-20%) are legumes like alfalfa, not grass hay. So a grass hay advertised at 15%+ is usually mixed with alfalfa, cut dangerously young, or an optimistic number.
Horses need enough protein — not the most
A mature horse in light-to-moderate work needs roughly 8-10% crude protein in the total diet. Growing youngstock, broodmares and hard-working horses need more, and get it from a top-up (alfalfa or feed). But for most horses, extra protein isn't stored as muscle — it's broken down and excreted, which raises water intake, urination and ammonia in the stable. More protein is a cost, not a bonus.
What we actually see — and publish
Good grass hay realistically measures around 8-12% crude protein; much local Iberian hay is far lower, often just 2-5%. Our French meadow hay is lab-tested every batch and typically measures around 8% crude protein — genuinely good grass-hay protein, at a safe, low sugar level, backed by an analysis you can see. We publish the real number, not the biggest one. When a horse needs more protein, we top up honestly with alfalfa or feed — rather than pretending grass hay can do it all.
Frequently asked
Is higher-protein hay better for horses?
Not necessarily. Most horses need adequate protein (about 8-10% of the diet), not the maximum. Very high grass-hay protein usually means it was cut young — which also means more sugar and less fibre. Excess protein isn't stored as muscle; it's excreted, raising ammonia and water use. The right protein for your horse beats the biggest number.
Why do some hays advertise 15-18% protein?
Those numbers usually come from legumes like alfalfa (which really are that high), from grass cut very immature (high sugar, low fibre), or from an optimistic crude-protein figure. Crude protein is estimated from nitrogen and includes protein the horse can't digest, so a big number can overstate what the horse actually gets.
What protein does Prime Hay measure?
Our French meadow hay typically measures around 8% crude protein — solid grass-hay protein at a safe, low sugar level, and we test every batch so you see the real value. Much local hay is only 2-5%. When a horse needs more protein, we top it up honestly with alfalfa or feed.
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