Does your horse remain stiff and lacking muscle development? Are you training hard but not seeing an improvement in the back muscles under the saddle? This often relates to the diet. How much protein does your forage contain? And what type of concentrate feed do you supplement the diet with? Upon evaluating the forage and concentrate feed ration, it may become apparent that the horse doesn’t have sufficient protein intake to build muscle mass. But what exactly are proteins, and why does a horse need them so much?


Proteins in Horses 

Proteins are the building blocks of the body and are essential for connective tissue, the immune system, and the production of hormones and neurotransmitters. Proteins are necessary for repairing and renewing the body. Not only do they repair muscle cells, but they also contribute to the repair of the skin, intestinal cells, red blood cells, and hormones. All these daily processes can be effectively carried out as long as there is an adequate supply of proteins in the diet. Proteins are composed of amino acids. Amino acids are arranged in a specific sequence to form proteins. Enzymes and acids break down the sequence of amino acids in the intestine. The individual amino acids are then absorbed into the bloodstream through the small intestine. The liver transports the amino acids to different parts of the body to support various bodily processes. 


Amino acids

Amino acids can be divided into two types: non-essential or dispensable amino acids and essential amino acids. Non-essential amino acids are synthesized by the body itself. Amino acids are composed of elements such as carbon, oxygen, hydrogen, nitrogen, and sulfur. Essential amino acids are obtained from the diet. Many types of feed, such as grass, alfalfa, and soy, contain protein. Each protein has its own specific pattern of amino acids. A balanced diet ensures that the horse receives an adequate amount of proteins and various amino acids. Each tissue in the horse’s body requires a unique pattern of amino acids. For example, the hair and hooves of the horse require a different amino acid pattern than muscle fibers. In the hooves, amino acids contribute to hardness, in bones, they facilitate calcium absorption, and in blood vessels, they promote elasticity. 


Essential Amino acids 

Horses must obtain all essential amino acids through their diet since their bodies cannot produce them. There are nine types of essential amino acids, each with its important functions: 

  1. Lysine, Involved in concentration, calcium absorption, bone tissue growth, collagen synthesis, and immune system support. 
  2. Tryptophan, Involved in immunity and stress management.
  3. Leucine, Involved in muscle tissue growth and repair, wound and bone healing, and sugar metabolism. 
  4. Valine, Important for muscle tissue growth and repair and proper functioning of the nervous system. 
  5. Isoleucine, Important for muscle tissue development, energy production at the cellular level. 
  6. Methionine, Important for skin and hair health, prevention of fat accumulation, liver detoxification, histamine breakdown, and antioxidant function. 
  7. Threonine, Involved in brain metabolism, digestion, and protein synthesis. 
  8. Phenylalanine, Involved in stress response, pain management, and weight control. 
  9. Histidine, Involved in growth. 

Non-Essential amino acids that are often deficient:

  1. Glutamine, Although not essential, glutamine can be essential in certain situations such as digestive issues, muscle recovery, and immune system support. 
  2. Arginine, Although not essential, arginine can be crucial for wound healing, fertility issues, and slow recovery after exercise. 
  3. Tyrosine, Although not essential, tyrosine is involved in muscle building. 

While these amino acids are classified as non-essential because the horse’s body can produce them, there are instances where they may be insufficient and can benefit from dietary supplementation to support specific functions and conditions. 

Muscle building | How does it work exactly? 

Protein is broken down into amino acids and nitrogen throughout the entire gastrointestinal tract. However, amino acids are only absorbed in the small intestine. The amino acids released after the large intestine cannot be utilized by the horse, but they can be utilized by bacteria. For horses that undergo active training, the development of muscle tissue is essential. During the training of your horse, the muscles are subjected to stress. This stress leads to the formation of small tears in the muscle fibers. The damaged cells are repaired, and the small tears are filled in by amino acids, resulting in the formation of new tissue. 


Muscle Building through Training 

An imbalance between nutrition and training can lead to an excessive number of muscle tears. If there is a protein deficiency in the diet, the body cannot adequately repair itself. Additionally, horses are often trained too much or too intensely. A horse that undergoes intense training every day (excluding gentle trail rides or relaxed lunging) does not have enough time to recover. These horses may have underdeveloped muscles in the topline and hindquarters. However, this does not mean that every horse should be fed a high-protein diet, as it does not always provide additional benefits. A significant portion of the protein remains unusable for the horse. A proper training program and sufficient rest also play a crucial role in muscle development. For a healthy horse, an excess of protein in the diet is not a problem. The kidneys eliminate the excess nitrogen, resulting in increased urination and a greater need for water intake. 

Protein requirements 

Which horses are more likely to have a protein deficiency? And which horses generally require more protein? 

Horses that need to perform require more protein to support muscle recovery. A horse classified as B level in dressage may have more difficulty with lateral movements and carriage compared to an experienced Z level horse that performs more advanced exercises such as flying changes and collected canter. A horse that is better trained has stronger muscles and better fitness, which means they require a shorter recovery period and fewer building blocks. Therefore, we can say that the protein requirement is not dependent on the level but on the condition of the muscles. Even in horses ridden recreationally, covering long distances or on challenging terrain, training should be gradually increased. These horses will also be better equipped for the work after improvement and muscle training. 

Which horses have an increased need for protein: 

  • Horses that perform (regardless of the level) 
  • Pregnant and lactating mares 
  • Horses in the growth phase (young horses in development) 
  • Breeding stallions 
  • Horses undergoing rehabilitation or recovery

High biological value 

The value of protein in the diet depends on its digestibility and amino acid profile. The higher the content of essential amino acids in the protein, the higher its biological value. Hartog Alfalfa, for example, contains approximately 18-20% crude protein, of which 50-60% is digested. Other protein-rich feed ingredients with a high biological value include soybeans and flaxseed. Source: 

Proper Nutrition 

Over the past years, numerous analyses of roughage have been conducted by various feed manufacturers and independent institutions. The results indicate that many roughages specifically used for horses have decreased in nutritional value. The nutritional value and protein content of roughage depend on factors such as grass fertilization, soil type where the grass is grown, and the harvesting period. Much of the land used for (horse) hay or pre-cut silage belongs to private individuals and nature organizations. In many cases, this land is less intensively fertilized and contains less protein compared to agriculturally managed grass. This is not an issue for hardy horse breeds or horses with low exercise levels. However, for actively ridden horses or those in growth stages, it often results in a protein deficiency. Coarse natural hay is rich in fiber, which is beneficial. Unfortunately, natural hay also tends to have higher sugar content than average. Only through a roughage analysis can you precisely know what you are providing for your horse. A roughage ration can be supplemented with products such as alfalfa, which is rich in naturally formed vitamins, minerals, and proteins. Alfalfa possesses a diverse amino acid profile. 

Power feed ration

In addition to upgrading the roughage ration, it is advisable to supplement with power feed. Many basic and sport pellets have a balanced energy ratio but relatively low (digestible) protein content and contain a significant amount of potentially burdensome substances derived from by-products of the food industry. Hartog offers a herbal pellet in its range, which includes pure grains, alfalfa, soybean, and flaxseed. The ingredients of alfalfa, soybean, and flaxseed have a high biological value and provide a varied amino acid profile. This is an ideal support for light to heavy exertion. 


Tips for muscle building and extra body: 


Roughage with more than 16% protein content is rare. Horses that are fed such roughage rarely have a protein deficiency or lack essential amino acids. If these horses are still provided with high-protein and high-energy feed, it can have negative effects on the gut flora, stool consistency, and cause stiff muscles. Excessive protein intake can also put additional strain on the kidneys, leading the horse to drink and urinate more. If a horse lacks muscle development despite sufficient protein intake, there may be other underlying causes, such as training methods and tack fit.