Fiber analyses can indicate the cell wall content of hay. Low-quality hay has a high proportion of cell wall material, and the cell walls are composed of a relatively large amount of indigestible compounds, such as lignin. Lignification of the cell wall, which occurs as hay plants mature, is the primary factor limiting forage digestibility. Not only is high-quality hay more nutritious, but it is also more palatable and digestible. Therefore, animals consume it in larger quantities.
Supplements can only partially compensate for low-quality hay in the diet.
In fact, horses can become colicky when fed hay of too high a quality. The primary criterion when judging hay for horses is not its energy value but its condition. Hay for horses should be free of dust, mold, and weeds. Factors Affecting Quality Numerous factors, both controllable management factors and uncontrollable environmental factors, influence hay quality. Unfortunately, quality and yield are usually inversely related.