Hay Preservatives

Alfalfa is usually wilted 15% or less moisture prior to baling for hay. However, harvesting at low moistures increases loss of leaves (protein) during baling and reduces nutritive value. In addition, long wilting times increases the risk for damage from rain. In order to retain more nutrients and prevent rain damage, hay can be baled at higher moistures but the risk of spoilage from undesirable microbial metabolism during storage increases dramatically. Although much is known about the microbiology of silage, less is known about microbial metabolism in moist hay. Although bacilli can be associated with spoilage of wet hay (> 20% moisture), most suggest that fungi are the microbes that cause spoilage problems in moist hay. Moist hay undergoes several distinct heating cycles when stored in stacks. The significance of the heating peaks and associations with either plant or microbial metabolism are poorly understood. It does appear, however, that if the moist hay does not undergo some heating, the bales never "dry down" during storage. Excessive heating of the hay bale can lead to an increase in heat damaged protein (acid detergent insoluble nitrogen, ADIN). Heat-damaged protein lowers the protein value of the hay.