Protein Deficiency in Horses 

Just like many other nutrients, there are different types of proteins, called “amino acids,” which are a vital component of the horse’s diet. While often linked to the energy that calories offer, proteins serve a completely different function. Protein provides your horse with amino acids, which support your horse’s connective tissues, including their bones and muscles. Amino acids are the basic components of a protein and they can be divided into two groups: essential and nonessential. Essential amino acids, such as lysine, arginine, and phenylalanine, are amino acids that must be consumed by the horse since the horse is unable to synthesize them. In contrast, nonessential amino acids (cysteine, proline, and glutamine etc.) can be produced by the horse, making these amino acids not critical parts of the horse’s diet if the total protein content of the diet is sufficient. 

Horses under two years of age and nursing mares are at the greatest risk of having a protein deficiency. It is important that your horse consumes enough protein, but it must be of good quality (high in EAA’s) and it all needs to be absorbed from the gut into the body. 

Signs of Protein Deficiency  

Some of the signs that would suggest your horse may be lacking protein in their diet may include: 

  • Dull coat 
  • Reduced appetite 
  • Stifled development or poor growth as identified by lower-than-average daily gain. 
  • Flagging Stamina. 
  • Poor hoof growth. 
  • Loss of muscle mass. 
  • Reduced milk production in lactating mares. 

Often one of the easiest indicators of good quality protein consumption is the horse’s top line because this is made of muscle only, which is almost all protein. There should be enough muscle on both sides of the spine to fill in the hollow otherwise seen in a horse with poor top line. 

Restoring Protein Levels 

Because a protein deficiency can leave some horses such as those under two years of age with lasting effects, it’s essential you start a treatment program as soon as possible. The simple solution is to add good quality protein to your horse’s diet. 

Crude protein is the absolute amount of protein in the feed. Not all proteins eaten are absorbed and used equally. Some sources of protein also have limited amounts of EAA’s making these proteins poor sources of protein for horses. The quality of the protein is based on the amount of EAA’s in the protein. The more EAA’s in the protein, the better quality it is. Supplements that provide amino acids, especially lysine, are recommended for a faster recovery. 

Sources of Protein 

The higher the quality of hay or grass, the higher the quality of protein consumed and the reduced chance of a protein deficiency in your horse. The more stalk in the hay, the higher the fiber and the lower the available protein. Therefore, if your pasture and hay is of poor quality and your pasture and hay is limited in quantity, your horse may not get enough good quality protein.  

Some other high-quality protein sources include pre formulated supplements such as Ranvet Topline FX, Ranvet 500, Power Formula, and raw materials such as legumes like soybeans, tick beans or lupins and seed meals from sunflower or canola are also common natural protein supplements for horses.  

The list below provides a breakdown of approximate protein percentages found in some common feed sources: 

  • Dried split peas (23-25% protein) 
  • Lucerne hay, cubes, or pellets (19-23%) 
  • Flaxseed meal (31-35%) 
  • Hemp seeds (33%) 
  • Chia seed (19-23%) 
  • Soybean meal (44-52%) 
  • Sunflower meal (26-30%) 
  • Wheat Bran (15-20%) 
  • Oats (11-14%) 
  • Barley (7 to 13%) 

As a final note, it is important to remember that no one supplement can magically build your horses topline overnight. Topline is built through a combination of correct work and a good quality diet. 


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Every product in the Ranvet range has been developed to meet a horse’s most specific need at any given time, be it in a training environment or on a breeding farm. Having pioneered the formulation of specific medications and dietary supplements for horses, the company is now recognised as a leader in the areas of equine health and nutrition.

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