Proteinkilder til heste – hvad er forskellen?

Protein sources for horses – what's the difference?

September 22, 2025Ingeborg Rahbek Pedersen

Overview of protein sources

Feed additive	Crude protein	Sugar	Starch	Advantages	Disadvantages / Notes
Soybean meal	45–47%	3–7%	3–5%	Very high and well-documented absorption (approx. 90%). Cheap per g of absorbed protein.	May be GMO (if not NON-GMO). Imported raw material.
Lucerne	14%	4–7%	0%	Good combination of fiber and protein. Provides chewing time.	Varying sugar content.
Green pills	13%	7–8%	0%	Pressed grass/clover. Supplements fiber and protein.	Relatively high sugar content – not ideal for frugal horses.
RC +Fiber Mash	12%	5%	4%	Good for sensitive stomachs. Provides fiber, fluid and moderate protein.	Not a concentrated protein source.
Beetroot pills	7%	7–9%	0%	Energy and fiber without starch.	Very low protein – not a protein source in itself.
Sainfoin	17%	5%	3%	Rich in protein, high in fiber, low in starch. Contains tannins with possible antiparasitic effect.	Tannins bind minerals → can cause deficiencies. Not recommended as a primary protein source.
Peas (whole)	22%	3%	40%	Relatively high protein.	Very starchy → not suitable for frugal/metabolically sensitive horses.
Horse beans	27%	3%	37%	Rich in protein.	Same challenge as peas: high starch content.
Pea protein isolate	about 80%	<2%	<2%	Extremely high in protein. Concentrated and easy to dose.	Highly processed. Lacks fiber. Expensive. Not widely documented for horses.
Brewer's yeast	40–50%	Low	Low	Contains protein + B vitamins. Can support intestinal flora.	Energy dense – horses can gain weight. Not a complete protein source.
Horselux Green Protein	53%	1%	0%	High crude protein, low sugar/starch.	Absorbability only assumed to be 55–60%. Very expensive: 25–27 kr per 100 g absorbed protein vs. 2 kr for soy meal.

Read more about the individual protein sources

Soybean meal – the concentrated protein source

Soy meal is the richest source of protein on the list and is often used when the horse has a high need for easily digestible protein – for example, young horses in growth, breeding mares or sport horses in hard work.

Crude protein: 45–47%
Documented absorbability: approximately 90% (Farley et al., 1995)
Low sugar and starch → suitable for many horses.

Lucerne – high in fiber and a natural source of protein

Lucerne (alfalfa) is a roughage source that provides both structure for chewing and protein. It is a good choice for most horses, but the sugar content can vary.

Crude protein: 14%
Sugar: 4–7%
Starch: 0%

Green pellets – pressed grass

Typically made from dried grass or clover, they provide both fiber and protein, but the sugar content is relatively high.

Crude protein: 13%
Sugar: 7–8%
Starch: 0%

RC's +Fiber Mash – combination of fiber and protein

A fiber-rich mash that both supports digestion and provides moderate protein.

Crude protein: 12%
Sugar: 5%
Starch: 4%

Beet pellets – energy and fibre, but low protein

Beet pellets provide easily digestible fiber and energy without starch.

Crude protein: 7%
Sugar: 7–9%
Starch: 0%
Not a protein source per se.

Sainfoin – natural protein and tannins

Sainfoin is similar to alfalfa, but has a slightly higher protein content. However, it contains tannins, which can inhibit the absorption of minerals (iron, zinc, copper, calcium).

Crude protein: 17%
Sugar: 5%
Starch: 3%
👉 Despite the possible antiparasitic effect, we do not recommend using sainfoin as a primary protein source.

Peas and broad beans – high protein, but high in starch

Peas: 22% crude protein, 40% starch
Broad beans: 27% crude protein, 37% starch
Can be used in smaller quantities for horses with high energy needs, but not suitable for frugal or metabolically sensitive horses.

Pea protein isolate – the concentrated alternative

Pea protein isolate is a processed product with up to 80% crude protein.

Advantage: highly concentrated → small amounts cover needs.
Cons: lacks fiber, expensive, and not widely documented for horses.

Brewer's yeast – protein and intestinal support

Brewer's yeast (Saccharomyces cerevisiae) contains 40–50% protein and B vitamins. Brewer's yeast supports the part of the intestinal flora that breaks down fiber and thus increases the energy utilization of the roughage. This is relevant if the roughage is of poor quality, or if the horse is fed a lot of starch. Many horses can gain weight if it is used in larger quantities. Therefore, it is primarily a supplement , not a complete protein source.

Horselux Green Protein – very expensive per g of protein absorbed

A concentrated protein product based on grass protein.

Crude protein: 53%
Absorption: assumed 55–60% (no documentation)
Sugar: 1%, Starch: 0%
Price: 25–27 kr per 100 g of absorbed protein vs. approx. 2 kr for soy meal.

👉 Calculation: For the horse to absorb 150 g of protein daily, it must have:

Soybean meal: 370 g/day → approx. 3.13 kr/day
Horselux Green Protein: 472–515 g/day → approx. DKK 37.7–41.1/day

Conclusion

Soybean meal is the most effective and well-documented source of protein for the price.
Alfalfa and green peas are good all-round sources, especially when you also want fiber.
RC +Fiber Mash is a good supplement for digestion and fluid intake, but not a strong source of protein.
Peas and broad beans contain a lot of starch → require care.
Esparsette may have benefits, but tannins pose a risk of mineral deficiency → not recommended as a main source.
Pea protein isolate and brewer's yeast are concentrated supplements, but are expensive and not suitable as daily protein sources for most horses.
Horselux Green Protein is significantly more expensive and without well-documented absorbability.

👉 The most important thing is to always start from the roughage analysis . It is the foundation that determines which protein source best supplements your horse's needs.

Read more: Sainfoin for horses – benefit or pitfall?