Protecting Hay Quality during Storage

When hay is first baled stored, it may go through a “sweat”, an increase in bale temperature. This increase in bale temperature is a combination of plant, bacteria, yeast, and fungi respiration. Plant soluble carbohydrates, principally sugars, are the source of energy for this respiration and increase in heat. As hay storage time increases, the hay loses Dry Matter (DM), and increases in Neutral Detergent Fiber (NDF) and Acid Detergent Fiber (ADF). If forages are stored at temperatures > 95° for extended periods, indigestible Maillard products may be formed. Round bales that are stored unprotected may weather on the outer edges; six inches of weathered hay may represent as much as 31% of the total bale. The weathered hay at the bale exterior has less digestible Crude Protein (CP), and has a higher NDF and ADF concentration than at the bale interior. Hay that is stored unprotected in the irrigated Sonoran Desert during the summer may become heat damaged. During extended storage periods, hay may be protected by placing the hay under a roof or by covering the hay with plastic tarp and thereby reduce losses in DM and reduce the increases in NDF, ADF, heat-damage.