Evaluation of Hay for Horses

While chemical analysis of hay represents the gold-standard for forage evaluation, horse owners can tell plenty about a hay’s quality by a thorough visual examination. Physical characteristics of hay quality include plant type, maturity at harvest, color, and moisture content.

For experienced horsemen, identifying the plants that compose individual bales of hay may be simple. Certain plants are easily discernible. Other plants may be more difficult to classify, and an expert may be needed to identify miscellaneous grasses or unusual plants. Suspect weeds should be noted as well. Generally speaking, the purer the bale, the higher quality the hay.

Hay maturity is determined through the presence of seed heads, stem coarseness, and a low leaf-to-stem ratio. Though they frequently have higher yields, first cutting hays are apt to be more mature than later cuttings. Second and third cuttings tend to have fewer stems and more leaves, which make them more nutritious, as leaves are rich in nonstructural carbohydrates and protein, and low in structural carbohydrates.

Color is not the end-all, be-all of hay evaluation, yet the most desirable hays are typically bright green. This color indicates the hay was cured properly with little likelihood of rain damage. A green color is also indicative of the amount of alpha-tocopherol (Vitamin E) and beta-carotene (Vitamin A) in the hay. A yellow or light-brown color points to rain damage, sun-bleaching, or overmaturity at harvest.  Sun-bleaching may occur during storage, when hay is exposed to direct light. In these instances, though, the majority of a bale might still be green with just discolored edges.

Hay quality is dependent on proper harvesting. Most notably, hay must be dried to less than 20% moisture. Hay that is baled too wet will mold and be unsuitable for consumption by horses, and hay that is baled too dry will be predisposed to leaf shatter (disintegration of leaves) or leaf loss. Legumes are especially prone to leaf shatter.