Using Hay in Equine Diets

Horses are non‐ruminant herbivores designed to utilize forages as the primary component of their diet. They have a non-compartmentalized simple stomach and an enlarged hindgut that accommodates fiber digestion. When fresh forages are unavailable, or when horses are confined to stalls or dry lots, conserved forages (hay) may be fed to meet their nutritional needs. Equine nutritional needs are based on requirements for digestible energy, and the six major classes of nutrients; carbohydrates, fats, proteins, minerals, vitamins, and water.

Nutrient requirements for horses depend on their physiological status (age, metabolism, weight) and their level of production (maintenance, growth, exercise, reproduction, and lactation). Selecting hay and incorporating it into the ration should be done with the individual horse's needs in mind. Most classes of horses can meet all or a large majority of their nutritional needs from good quality hay alone. However, hay alone may not meet the nutrient requirements of horses with increased needs required for growth, reproduction, and exercise.

Horses require 2 to 3% of their body weight in feed (includes hay and grain) each day. At least half of their daily feed intake should be in the form of roughage such as fresh forage or hay to optimize digestive health. The amount and type of hay a horse needs ultimately depends on the individual horse's nutrient requirements and the quality of the hay. Hay quality should be determined by laboratory analysis. Following are three examples of how to correctly incorporate forage into your horse's diet.

The nutrient requirements of idle adult horses can be met by good quality grass hay alone. Following is an example of a feeding program including hay requirements for an adult idle horse.

 Horse Weight: 1,000 pounds
 Required Daily Feed Intake: 2%
 Total Intake Per Day: 20 pounds
% of Hay in Daily Ration: 100
% of Concentrate in Daily Ration: 0
 Amount of Hay: 20 pounds (daily)
 Amount of Concentrate: 0 pounds

Hay should be analyzed for nutrient content to identify any deficiencies. For example, many hays are low in some vitamins and minerals, and supplementation is often necessary. Most commercial feed companies offer a vitamin and mineral supplement that is low in digestible energy and complements the nutrient content of forages. These supplemental concentrates are typically fed at a rate of 1 pound per day for idle adult horses.

The nutrient requirements of working horses are determined by the intensity and duration of exercise. Exercise increases the nutrient requirements of horses, and hay alone may not be sufficient to meet their needs. To meet the increased requirements of working horses, cereal grain based concentrates are often included in the daily ration. Following is an example of a feeding program including hay requirements to meet the needs of a horse in moderate exercise. Moderate exercise is classified as 3 to 5 hours per week.

 Horse Weight: 1,000 pounds
 Required Daily Feed Intake: 2%
 Total Intake Per Day: 20 pounds
% of Hay in Daily Ration: 75
% of Concentrate in Ration: 25
 Amount of Hay: 15 pounds (daily)
 Amount of Concentrate: 5 lbs

Grass hay alone may not be sufficient to meet the needs of working horses. Alfalfa hay is typically higher in digestible energy and nutrients. and may be sufficient in meeting the needs of working horses, particularly those in light or moderate work. Heavy and very heavy exercise will require an increased percentage of concentrates in their diet, but forage or hay should make up at least 50% of the daily ration.

The energy and nutrient requirements for growing horses are greatly influenced by their age and rate of growth. For young horses in training (18 to 24 months of age), intensity of exercise also affects nutritional needs. The following example outlines a suggested feeding program and hay requirements for a 12 month old horse at a 1 pound average rate of daily gain.

 Horse Weight: 700 pounds
 Average Daily Gain: 1 pound
 Required Daily Feed Intake: 2%
 Total Intake Per Day: 14 pounds
% of Hay in Ration: 75
 % of Concentrate in Ration: 25
 Amount of Hay: 10.5 lbs (daily)
 Concentrate: 3.5 lbs (daily)

Good quality grass hay, alfalfa, and grass/alfalfa mixed hays can be used in feeding programs for young growing horses. If feeding a substantial amount of alfalfa, ensure the Ca:P ratio of the diet is approximately 3:1 and never inverted. Young horses with increased nutrient requirements (from training or exercise) will require an increased in concentrates, but forage should make up at least 50% of the diet. Good quality hay provides ample nutrients to meet the needs of most horses. Regardless of the class of horse, forages should make up at least 50% of the daily ration. Optimizing forages in your horse's diet will result in a healthier horse and can also result in significant financial savings. More information can be found in the 2007 National Research Council's Nutrient Requirements of the Horse.


A special thank you to Dr. McIntosh for sharing her expertise and article.


By Bridgett McIntosh, PhD, University of Tennessee
Published at the University of Minnesota Extension Horse Newsletter (May 2009)