FORAGES FOR HORSES

By Dr. Katie Young, Equine Nutritionist, Purina Mills, LLC

Why should horse owners be concerned about forages for their horses? Horses need to be fed at least one percent of their body weight daily (dry matter) as forage. Most horses are fed more than that; many receive two or more percent of their body weight per day in grass or hay. This means that a 1000 pound horse may easily eat 15-20 pounds per day of hay, along with 3-6 pounds of grain ration such as Strategy or Omolene. When problems occur that may relate back to nutrition, people usually look to the grain ration. However, when the vast majority of the horse’s diet is hay, we should probably pay more attention to the important nutritional role that the forage plays in the horse’s nutritional status.

There are several factors that affect the quality of hay, therefore the nutrient content. The higher the quality of the hay, the better the horse’s digestive tract is able to digest and absorb the nutrients contained in the hay.

The factors that affect the quality of the hay include plant species, fertilization, maturity at time of harvest, season at which hay is harvested, climate conditions, storage condition, and age (time since cutting).

The maturity of the plant at time of harvest determines the hay quality more than any other factor. Young, leafy, immature plants contain more protein, energy and minerals than older, stemmier plants. As a plant matures, it contains more indigestible fiber (lignin), therefore is less digestible for the horse, as well as containing less protein, energy and minerals. To ensure high quality hay, plants should be harvested at the proper stage of maturity, for instance, timothy should be cut in the pre-bloom or early-bloom stages for the highest nutrient content.

Plant species (e.g. grass vs. legume) has an impact on the nutrient content of the hay, but not as most horse owners believe. The maturity of the plant when it was cut has much more influence. Alfalfa tends to have more protein, energy and calcium than grass hays, but research has shown that a good quality grass hay may provide more nutrients than a medium or low quality alfalfa because the higher quality grass hay is more digestible (less fibrous). For example, for protein to be of value to a horse as amino acids, it must be digested in the horse’s upper gut (stomach and small intestine). Since the fiber in hay can only be digested by microbes in the horse’s hind gut, the more fiber in the hay, the more that hay is digested in the hind gut. In one study, when horses were fed medium quality alfalfa hay, only 2% of the protein was digested in the upper gut. This means that 98% of the protein was of no benefit as protein to the horses. Horse owners sometimes feel that alfalfa is always a better choice for horses than grass hays, but that is not necessarily true. Further, sometimes high quality alfalfa does not provide enough fiber to maintain a healthy hind gut in the horse. A certain amount of fiber (bulk) is necessary to ensure the health of the microbes in the hind gut, as well as helping to maintain proper motility in the hind but.

Fertilization primarily affects yield per acre rather than nutrition of any one bale of hay. The season at which the hay is harvested affects quality in that digestibility is highest for forages harvested in the spring, somewhat lower in mid to late summer, and then it rises slightly in autumn. Climate conditions, such as excessive moisture or drought can affect the quality of hay, especially since climate conditions can affect when the hay is cut. Often the plants become more mature than optimum because climate conditions are not conductive to harvesting at the best time.

Storage conditions and age (time since cutting) primarily affect vitamin content of hays. Many vitamins are not very stable over time and lose biological activity. Environmental conditions such as heat, sunlight and rain can hasten the loss of vitamin activity in hay.

Characteristics to look for in choosing high quality hay include:

·High leaf to stem ratio (indicates less mature plants)

·Small diameter stems (less mature plants)

·Fresh small and appearance

·Cleanliness

·Color (faded, yellow or brown color may indicate aged hay or poor storage condition).

·Few seed head or blooms (less mature plants).

Hay analysis may provide more information, but the results need to be interpreted with caution. For instance, the crude protein determined by analysis does not indicate the site of digestion in the horse. A hay that tests high in crude protein and also high in acid detergent fiber (ADF) is not well digested in the horse’s upper gut, thus the amino acids from the protein are not readily available for absorption in the upper gut. A hay with lower crude protein and lower ADF may actually provide more nutrients, including protein, energy and minerals to the horse.

So, how can we ensure that out horses are getting adequate nutrition without testing every bale of hay? First, we need to choose hay with attention to the characteristics of quality that we can see without necessarily testing each bale. Then we need to choose a feed to go with that hay to ensure that all the horse’s nutritional needs are met. At Purina, we formulate the feeds to balance out the nutritional deficiencies that we commonly expect from hays and grasses. The feeds contain adequate protein (amino acids), energy, vitamins and minerals to compensate for what is frequently missing in the forages. Then the horse owner only needs to determine which feed best matches that horse’s lifestyle (e.g. Omolene 300 or Strategy for young growing horses, Ultium, Omolene 200, Race Ready or Strategy for performance horses, etc). For horses that obviously receive adequate energy (calories) from hay or grass – i.e. the horse maintains adequate body condition or possibly gets fat on grass or hay alone, the horse owner can feed Nature’s Essentials Born to Win or Mare & Maintenance. These concentrated supplements contain amounts of protein, vitamins and minerals so that they can be fed in small amounts (usually 1-2 pounds per day) to meet the horse’s requirements without adding a large number of calories.

For more information on which feed will best meet your horse’s requirements, see your local Purina Dealer, contact your Purina representative, or visit our website at    http://horse.purinamills.com

Back to Archives