Original Research
Voluntary Intake of Four Hay Types by Horses

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Abstract

Alfalfa, teff, oat, and wheat hays were fed to eight mature horses to determine voluntary intake of each hay type. After a 2-week adaptation period during which each horse was offered all four hay types each day, a 4-week study was conducted in which two horses were offered each type of hay each week, usually at the rate of 2.2% of initial body weight. Refused feed was collected and weighed the last 5 days of each week to calculate voluntary intake. Horses consumed significantly more alfalfa hay than the other hays. Wheat and teff hays were consumed in significantly lower amounts than alfalfa, but significantly more than oat hay. Across the 5 days during which voluntary intake was measured each week, hay consumption increased each day, reaching levels significantly greater than day 1 by day 4, when measured as a percentage of body weight, and day 5 when measured as a percentage of feed offered. Only alfalfa hay, at the amount consumed, met 100% of nutrient requirements for digestible energy, crude protein, lysine, calcium, and phosphorus for horses in maintenance condition. Teff hay met all nutrient requirements except digestible energy. Neither wheat nor oat hays met 100% of any of these nutrient requirements. Alfalfa and teff hays averaged about 12% nonstructural carbohydrate content (NSC), whereas wheat and oats hays contained about 30% NSC. The lower NSC content of the alfalfa and teff hays makes these more suitable for horses with problems related to carbohydrate metabolism or for refeeding starving horses.

Introduction

Because forage is the largest component of the diet of most horses, its quality and acceptability is of high priority to horse owners. Hay not only contributes to meeting the nutrient requirements of horses, but is also an important source of fiber or bulk in the diet. Palatability of hay is variable, and factors that influence palatability may not be discernable by chemical analysis or visual inspection.

In the western states, alfalfa hay (Medicago sativa) is widely available and is palatable to most horses. However, the protein and calcium content of alfalfa hay exceeds the nutrient requirements of most classes of horses, and therefore horses can become overweight if fed alfalfa hay generously. Cereal hays, particularly oat (Avena sativa) and wheat (Triticum aestivum) hays, are regionally available, and the nutrient content better matches the energy, protein, and calcium requirements of mature horses. Age of plants at harvest influences the grain (and therefore the starch) content of cereal hays. High starch content, especially in concert with selective eating of parts of the hay by horses, can result in horses consuming significant levels of starch when fed cereal hay. Horses with problems related to carbohydrate metabolism should not be fed forage high in starch or other nonstructural carbohydrates (NSC). Cereal hay is often variably palatable, and visual appraisal does not always indicate palatability.

Warm season grasses tend to accumulate lower amounts of NSC and, as such, may be suitable for horses with equine metabolic syndrome, insulin resistance, laminitis, or to those that are overweight. Teff (Eragrostis tef) hay has received much attention as a good hay for horses for these reasons as well as because of its hardy nature, heat tolerance, and capacity for multiple cuttings despite being an annual grass. Promoters of teff hay tout its palatability for horses, but with little scientific evidence.

The goal of this study was to evaluate the horses' voluntary intake of the following four kinds of hay commonly grown in the western states: alfalfa, oat, wheat, and teff hays. Evaluation of voluntary intake of these four hay types, all grown under similar field conditions, may help horse owners choose hays with appropriate palatability and nutrient content as well as understand how palatability may influence nutrient intakes from these feeds.

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Horses and Housing

This study was conducted in October and November 2010 in central California. Eight nonpregnant mature mares were used in this study. Six Hackney horse and two Quarter horse mares ranged in age from 4 to 18 years and ranged in initial body weight (BW) from 475 to 640 kg. Before the study, the horses were maintained on permanent pasture and were fed alfalfa hay twice daily.

In preparation for this study, the eight horses were transferred from pasture and housed in adjacent or opposing (across a

Results

Voluntary dry matter intake, measured as a percentage of BW, was significantly affected by period, day, and hay type. Voluntary dry matter intake, measured as a percentage of feed offered, was significantly affected by day and feed type, but not by period.

Voluntary dry matter intake was significantly greater for alfalfa hay than for the other hay types. Voluntary dry matter intakes of teff and wheat hays were similar and were significantly greater than that for oat hay (Table 1).

Voluntary dry

Discussion

As expected, horses consumed more alfalfa than the other hay types. A preference among horses for alfalfa over other hay types has been shown in other studies [3], [4]. In a review of literature on voluntary food intake by horses, Cuddeford [5] summarized several studies on voluntary dry matter intake of different types of hay, and reported that in almost all studies in which alfalfa hay was compared with other types of hay, alfalfa hay was found to be consumed at the highest levels.

Wheat and

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