MATCHING FORAGE to your Horse's NUTRIENT  NEEDSMatching Forage to your Horse's Nutrient Needs

By Dr. Tania Cubitt and Dr. Steven Duren, PhD

From  Canadian Horse Journal - September 2014

Forage (fibre) from pasture and/or hay is the predominant ingredient in the diet for most horses. The digestive system of a horse requires forage to function properly. Horses that have access to abundant pasture will satisfy their need for forage by grazing. Horses kept in stables, horses kept in grass free paddocks, and most horses during the winter months depend on their caregivers to provide the proper amount and type of forage. Given the importance of hay in horse diets, this is a refresher course in hay.

What is hay? Hay is plant material that has been grown, cut down, dried, packaged into bales, and stored for feeding at a later time. Just about any type of plant can be made into hay. To have a good quality horse hay you must start with nutritious plants, harvest those plants at the proper stage of maturity to maximize nutrient content, and dry the plants properly so they don't spoil or become mouldy. In general, horse hay falls into two broad categories: legume and grass. 

Legume hay is generally higher in protein, energy, and minerals than grasses harvested at the same maturity. Examples of legume hays include alfalfa and clover. 

Grass hays include timothy, orchard grass, bluegrass, brome grass, rye grass, fescue, and Bermuda grass. 

Other plants with a similar nutrient profile to grass hay are cereal grain hays. Cereal grain plants such as oats, barley, and wheat generally make good hay when harvested during their early growth stages before seed heads become predominant. 

Most any legume, grass, or grain hay can be fed to horses if it is high quality.

Selecting a Hay Type

With so many types of hay available, how do you choose one appropriate for your horse? The goal is to match the nutrients provided by the hay with the nutrient requirements of the individual horse. For example, the nutrient requirements of a pregnant mare are higher than the requirement of a mature gelding.


Quality hay, of any type, can be fed to any class of horse. If hay with a low or moderate nutrient content is fed to a horse with high nutrient requirements, the nutrients lacking in the hay must be supplied in the grain concentrate portion of the diet. Likewise, if hay with a high nutrient content is fed to horses with low or moderate nutrient requirements, less grain is needed to balance the diet. More important than the type of hay fed is the amount of good quality hay fed. Feed a minimum of one pound of hay per 100 pounds of body weight per day.

Determining Hay Quality

Horses require good quality hay as their digestive tract is "one-way" in direction. Horses are not normally capable of


Table 2


Stage of  Maturity     

Early cut hay is more palatable and digestible. Look for short plants with few or no seed heads.


High quality  hays have a high percentage of leaves (blades) to stems. Look for abundant leaves or blades, small thin stems.


Bright green colour indicates proper curing, high vitamin content and good palpability. Loss of colour indicates weather damage. Look for bright green colour.

Foreign   Material  

 Hay should not contain weeds or foreign material such as dirt, wire, and sticks, look for grass or Alfalfa plants with no weeds.


Musty or rotten odours indicate low quality hay that was not properly cured and stored. Look for: clean, fresh smelling hay free of visible mould or excessive dust.

vomiting, and they become sick if hay is mouldy or dusty. Hay quality can be determined in many ways. Stage maturity, leanness, colour, foreign material, odour, and condition are physical parameters that can be judged to determine quality.

Physical quality can be determined by observation and comparison of hay samples. Table 2 indicates what to look for in judging these physical parameters. It must be noted that lower nutritive value hay can be fed, but it will require increased grain supplementation. Mouldy or very dusty hay should not be fed at all.

Health Concerns Related to Different Hays

Finally, there are a few health concerns that merit attention when choosing horse hay. High moisture hay (haylage or baleage) may be fed to horses, but many have increased risk of moulds or toxins such as botulism. Some hays are susceptible to fungal infections, including rye (which may be infected with ergot) or fescue (which may be infected with endophyte fungus).

Sorghum/Sudan grass hybrids may result in health disorders and should be avoided. 

Red clover harvested in warm humid weather may become infected with a fungus that causes "slobbering." 

Alfalfa may contain blister beetles, primarily if sourced from the central US, and should be examined with the aim of ascertaining any infestation. 

In general these problems are not common, but awareness of the possibilities will help when making informed decisions about hay selection.

Does Hay Lose its Nutritional Value While in Storage?

Hay begins to lose its nutritional value at the time of cutting and continues to lose nutrients both while drying in the field and while in storage. The nutrients most affected by harvesting and storing are vitamins. Conversely, the protein and mineral content of hay is quite stable. All green parts of growing plants are rich in carotene and, therefore, have a high vitamin A value. In fact, the degree of greenness is a reliable index of vitamin content. Approximately 50 percent of the Vitamin A in hay may be lost during the first 24 hours of the curing process. If the hay is subjected to rain or weather damage, vitamin losses are greater. 

Vitamin depletion continues during storage with the rate of destruction determined by temperature, exposure to air and sunlight, and length of storage. 

When hay is stored under average conditions, vitamin content can be expected to decrease by approximately seven percent per month. If the hay is left outside, without cover, the vitamin losses will be more substantial. 

Again, the colour of the hay is the best, non-laboratory means of determining vitamin content. Remember, the greener the hay, the higher the vitamin level.

When Buying Horse Hay, What Nutrient Ranges are Acceptable?

The only reliable method to determine nutrient content of hay is laboratory analysis.  Remember, along with chemical quality, hay should also be of good physical quality.