Proteins are the building blocks of all tissues in the horse’s body and are involved in nearly all vital bodily processes. A protein consists of different amino acids. After being broken down by gut flora, these amino acids can be absorbed through the intestines into the bloodstream. From there, they are transported to the parts of the horse’s body where they are needed—for example, for muscle development or cell repair.

Essential Amino Acids

The proteins in a horse’s body are made up of twenty different amino acids. Ten of these can be synthesized by the horse; the other ten must come from the diet. Most of these so-called “essential amino acids” are present in sufficient quantities in roughage. However, some amino acids are often lacking in basic feeds—such as lysine, methionine, and threonine, and sometimes also tryptophan.

Extra Protein or Amino Acids?

Turning your horse out on fresh grass is an easy way to add more protein to the diet, as grass is rich in protein. If grazing isn’t an option, there are special amino acid supplements for horses that may have a protein deficiency—such as under-muscled horses or sport horses with high protein needs. These supplements mainly contain the essential amino acids that are often missing in hay, such as lysine. Horses can also extract amino acids from protein-rich products like spirulina algae or pea protein. The amino acid profiles of these products vary. You can also consider (healthy) horse feeds that contain protein-rich ingredients.

Does my horse need it?

Horses from hardy breeds or those that graze a lot and don’t do heavy work usually get enough from a balancer with vitamins and minerals. These horses generally don’t need extra protein or amino acids. However, if your horse mainly eats roughage from unfertilized land, there’s a relatively high chance that it lacks sufficient protein. Sport horses, foals, and broodmares are particularly at risk of protein deficiency. Good to know: almost 40% of Dutch roughage samples contain too little protein.

But not too much

Although too much protein isn’t necessarily unhealthy for a horse, it’s inefficient and has environmental consequences. A horse will excrete the excess protein as ammonia in its urine. That’s why it’s important to find a good balance in protein intake.