Protein for Horses: Essential Equine Protein Guide

Picture a young foal taking its first shaky steps, a seasoned performance horse powering through a demanding training session or an ageing gelding gently grazing in the afternoon sun. What ties these moments together is something unseen but absolutely vital - protein.

The Importance of Protein for Horses

Deep inside the horse’s body, protein plays a starring role. Every structure from muscles, skin, bones, tendons, ligaments, organs and hooves relies on protein as a building block. It’s also central to the immune system, forming antibodies, and essential for creating hormones and enzymes that regulate countless bodily functions and metabolic processes. And when energy sources are low? Protein even steps in as a backup fuel.

For a mature horse with no additional requirements, protein should make up around 10% of the diet. If given access to high quality grazing or forage this should meet the majority of this requirement. However, there are several groups of horses that may have an increased protein demand, these include:

• Foals and yearlings going through periods of rapid growth require more protein to build strong muscles, bones, and tissues. A deficiency during this stage can result in developmental problems.

• Pregnant and lactating mares need higher protein levels to support foetal growth and milk production.

• Performance horses in heavy training require additional protein to promote muscle development and repair tissues damaged during intense exercise.

• Senior horses (aged 15+) may have reduced digestive efficiency and benefit from highly digestible protein sources. As horses age, they may struggle to maintain muscle mass and their immune systems can decline increasing the need for protein.

• Sick horses and those recovering from illness or injury often require extra protein to support the repair of damaged tissues and immune function.

Protein Digestion in Horses

In the horse’s body protein digestion starts in the stomach where gastric juices start the breakdown. The majority of protein digestion is carried out in the small intestine where digestive enzymes break it down into amino acids for absorption into the blood stream. Around half of a horse’s protein intake will reach the hind gut where it is fermented by the gut microbiome.

Consuming excess amounts of protein can lead to a build up of ammonia and other waste products, this often results in increased urination with a characteristic strong smell. Ammonia build up in the stable can irritate the respiratory system so feeding excessive amounts of protein should be avoided.

Protein Deficiency in Horses: Signs to Watch

An average 500kg horse at maintenance will require approximately 630g of protein per day. If a horse’s diet is deficient in protein, this can have a number of negative effects on the body. Signs of protein deficiency include:

• Dull coat
• Poor hoof quality
• Weakened immune system
• Decreased athletic performance
• Poor muscle development
• Slow growth rates in young horses
• Decreased milk production in lactating mares

Best Protein Sources for Horses

Grass & Forage - Grass, hay or haylage should fulfil the majority of a horse’s protein intake. The protein content of grass and forage can vary depending on factors such as soil nutrient levels, paddock maintenance and time of year.

Legumes - Legumes such as soya, alfalfa and sainfoin are much higher in protein than other grass types. Some horses may be sensitive to legumes due to their higher energy and protein content. Sainfoin is a great option for horses who may be more sensitive to alfalfa and soya products. Soya and its byproducts are typically found in concentrate feeds and pelleted balancers whilst alfalfa and sainfoin are more commonly used as chaffs.

Peas - Flaked peas are commonly found in high protein mixes however pea meal can also be purchased separately to add into feed. Peas are high in protein and low in energy making them a great option for horses who require additional protein without the added energy and fizz that can come with traditional concentrate feeds.

Chia seeds - Chia seeds are considered a complete protein meaning they contain every single essential amino acid which need to be provided by the diet.

Linseed - Both linseed oil and micronised linseed provide moderate amounts of protein alongside Omega 3 fatty acids. Linseed is very palatable and easily digested, it also has a much more favourable ratio of Omega fatty acids than other vegetable oils.

Conclusion: Optimising Equine Protein Intake

Protein is an essential nutrient that supports nearly every aspect of equine health. While forages provide the foundation, where needed, strategic use of high-quality protein sources ensures horses receive the amino acids they need. Whether raising a foal, managing a broodmare or supporting a performance horse, paying attention to protein intake can make the difference between adequate nutrition and optimal health.