Submitted to: Experiment Station Bulletins
Publication Type: Experiment station
Publication Acceptance Date: 6/24/2013
Publication Date: 9/6/2013
Citation: Coblentz, W.K., Undersander, D.J., Bertram, M.G. 2013. Propionic acid preservatives for hay. Experiment Station Bulletins. Vol. 15. No. 5. Interpretive Summary:
Technical Abstract: Hay producers working in humid environments are well-acquainted with the consequences of baling moist hays, which include heating, molding, losses of dry matter and nutritive value, and the possibility of spontaneous combustion. Traditionally, the effect of heat damage within forages has focused on reduced bioavailability of crude protein within ruminant animals; however, recent research also has shown that losses of energy from heated hays are perhaps more important. As a result, preventing or limiting spontaneous heating is critical to prevent hay fires, but also to maximize hay quality. Results of numerous research studies dating back nearly 40 years indicate that propionic acid-based preservatives clearly alter the normal patterns of spontaneous heating within moist hays, but do not eliminate heating entirely. Research results have been somewhat erratic, and this may be related to wide variability in production practices, the specific formulation of the preservative, baling equipment design, bale size and/or type, as well as storage management. Based on these studies, it appears that preservatives are most effective when initial bale moisture is <25% (15 to 20% is the normal threshold for safe storage, depending on bale size and type) and they become less effective as bale moisture increases. These products also appear to be more effective when applied within the bale chamber to rectangular bales rather than at the pick-up assembly, which is common for large-round balers.