Horses' Voluntary Intake of Four Hay Types

The majority of the equine diet should be based on forage, which serves as a source of fiber and nutrients. However, some horses might not readily consume all types of hay. To that end, a team of California State University researchers set out to compare four hay types to determine which horses are most inclined to consume.

Hay palatability depends on a variety of factors, such as species and maturity at harvest. In addition, some hay types might not be suitable for all horses, depending upon individual nutrient needs for maintenance, work, growth, or reproduction. In the current study, led by Anne V. Rodiek, PhD, researchers evaluated horses' voluntary intake of alfalfa, oat, wheat, and teff.

The study involved eight mature mares housed in individual, partially roofed pipe pens. During a two-week adaptation period, all horses received one flake of each hay type daily (alfalfa and wheat hay in the morning and oat and teff in the evening). During the following four-week evaluation period the horses were paired and fed the same hay at the same time.

The team separated the horses into four groups of two, each of which consumed each type of hay alone for one week at a rate of 2.2% body weight (as determined by a weight tape) increased to 2.5% body weight if the horse consumed all the hay during the feeding period. The researchers removed any leftover hay prior to the next feeding and weighed it during the last five days of each week to calculate voluntary intake.

The team also collected samples of each hay type to analyze nutrient composition.

After reviewing the results, Rodiek concluded that:

  • Horses voluntarily consumed more alfalfa hay over all the other hay types and showed a clear preference for alfalfa hay;
  • Horses consumed wheat and teff hay at a lower rate than alfalfa, but more than oat hay; and
  • Chemical composition of the four hays did not serve as a predictor of voluntary intake in this study.

Rodiek noted that although the wheat and oat hays' chemical composition did not differ, the horses consumed more wheat hay than oat hay. She believes this could have been due to the wheat hay having more grain in it than the oat hay.

Additionally, the team found that the non-soluble carbohydrate percentage was higher for the wheat and oat hay compared to alfalfa and teff hay.

Finally, Rodiek noted that hay intake increased throughout each week of the study, and the only hay that was voluntarily consumed to meet the horse's energy requirements was the alfalfa hay. Horses consumed enough alfalfa and teff hay to meet their protein, lysine, calcium, and phosphorus requirements; however, neither oat nor wheat hay were consumed to meet any of these requirements.

The study, "Voluntary Intake of Four Hay Types by Horses," appeared in September in the Journal of Equine Veterinary Science. The abstract can be viewed online.

Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.