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Equine Protein RequirementsBy Kentucky Equine Research Staff · January 21, 2010

Horse owners want to provide their horses with adequate nourishment, but they may be confused about the best way to meet the protein requirements of animals with different workloads or ages.

While each horse needs to be considered as an individual, these basic guidelines may help to answer many questions.

How much protein does a horse need?
A horse's requirement for protein is determined by the animal's stage of development and workload.

Some general recommendations are listed below (please note, intakes mentioned are merely for the purposes of illustrating what is needed to meet protein requirements alone, but will likely not meet requirements for other nutrients).

  • A mature horse (average weight of 1100 pounds) needs about 1.4 pounds of protein a day for maintenance, early pregnancy, or light work. The horse usually ingests at least this much protein by grazing or eating grass hay (dry matter intake of about 22 pounds).
  • A mature horse doing moderate to heavy work needs about 2 to 2.15 pounds of protein a day. An owner could feed 22 pounds of grass or hay and add 2 to 4 pounds of fortified feed to meet the protein requirement.
  • A broodmare in late pregnancy needs high-quality protein to build placental and fetal tissue. Forage with a moderate percentage of alfalfa may provide this protein, but mares on marginal grazing benefit from the addition of 2 to 4 pounds of concentrate containing 13 to 16 percent protein.
  • A broodmare in the first three months of lactation requires about 2.75 pounds of protein each day. Besides grass or hay, she might need up to 7 pounds of fortified feed to ensure this much protein in her diet.
  • Protein needs are lower for broodmares in late lactation (after three months). Grass or hay and 2.5 pounds of fortified feed would supply a requirement of about 2 pounds of protein.
  • Weanlings weighing 550 pounds need about 1.6 pounds of protein. Because these younger horses eat less grass or hay, grain can be increased to 7 pounds a day.
  • Yearlings weighing 850 pounds eat more grass or hay and require about 4.5 pounds of concentrate to bring protein intake to 1.75 pounds a day.
  • To meet the protein demands of young horses in training, owners may need to feed as much as 7 pounds of concentrate along with 14 pounds of hay to provide the 2 pounds of protein that is required.

What is meant by high-quality or low-quality protein?
All horses need protein, but not all protein is the same. Protein is made up of different amino acids, some of which can be synthesized within the horse's body. Amino acids that cannot be synthesized are called essential amino acids and must be supplied in the feed. High-quality protein is that which supplies the essential amino acids in the proper ratios. It is possible for a horse to eat enough low-quality forage to meet its crude protein requirement and still not be properly nourished.

Why is protein so important for young horses?
Lysine, methionine, and threonine are the most important amino acids that must be provided in equine rations. Diets for young horses need to include sufficient lysine to support growth and development.

The protein in mare's milk is a rich source of lysine, as is the soybean meal included in some concentrates. Legumes such as alfalfa also provide significant amounts of lysine, while grasses and most cereal grains contain lower percentages of this important nutrient.

Do older horses need protein?
Adult horses need protein only for repair and maintenance of body tissues, so their total requirement is fairly low. Many mature horses get all the protein they need (about 10% of the diet, on average) from grass or hay. Owners can confirm that this need is met by having pastures and hay analyzed.

If analysis shows that the protein level is below 10%, an easy way to boost protein consumption is to offer some alfalfa hay along with, or instead of, the low-quality forage that has been provided.

Heavily exercising horses have a somewhat higher need for protein than maintenance horses, and the protein requirement is highest for late-pregnant broodmares and those in the first three months of lactation.

If these horses also require extra energy, the addition of concentrated feed to the diet can increase the intake of both energy and protein.

Is there a low-calorie way to provide protein to overweight horses?
Many people are faced with the problem of trying to provide easy keepers with good nutrition while preventing excessive weight gain. Increasing the horse's exercise is often helpful, but this method is not always practical. For example, it might be difficult to apply this plan to an unridden broodmare that needs the nutrients in a concentrate but tends to gain weight easily. This dilemma can be solved with the use of a balancer pellet (often available directly from your feed manufacturer).

These products are designed to deliver protein, vitamins, and minerals without significantly increasing caloric intake. With protein percentages from 14% to over 30%, these supplements are fed in small quantities to fortify the horse's diet without providing unnecessary calories.

How do I know what feeding program is best for my horse?
There are multiple ways to meet a particular horse's protein requirement by selecting from the various types of forage and the wide variety of available feed products. To ensure the proper amounts of protein and energy in equine diets, begin with high-quality forage and then supplement as needed with a balanced concentrate designed for the type of horse you are feeding.