Choosing hay and incorporating it into the ration should be done with the individual's needs in mind. Hay alone may not meet the total dietary requirements of young, growing horses or those used for high levels of performance. However, high quality hay may supply ample nutrition for less active adult horses. For optimum health, nutritionists recommend that at least half of this should be roughage such as hay. For a 1000 pound horse, that means at least 10 pounds of hay each day.
Most people buy hay based on how it looks, smells and feels.
Ask that one or several bales be opened so you can evaluate the hay inside the bales. Choose hay that is as fine-stemmed, green and leafy as possible, and is soft to the touch. Avoid hay that is overcured, excessively sun-bleached, or smells moldy, musty, dusty or fermented. Examine the leaves, stems and flowers or seed pods to determine the level of maturity. Avoid hay that contains significant amounts of weeds, dirt, trash or debris.