Submitted to: Popular Publication
Publication Type: Popular Publication
Publication Acceptance Date: 3/1/2013
Publication Date: 3/27/2013
Citation: Coblentz, W.K., Coffey, K.P., Bertram, M.G. 2013. Effects of a propionic-acid based preservative on storage characteristics of alfalfa-orchardgrass hay in large-rectangular bales. Popular Publication. pp. 22-2. Interpretive Summary:
Technical Abstract: For many years, various formulations of organic acids have been marketed as preservatives, most specifically for use on hays that could not be field-dried to moisture concentrations low enough to reduce or eliminate spontaneous heating during storage. These preservatives are often propionic-acid-based products that are formulated to create an unfavorable environment for growth of storage microflora, and are buffered to limit oxidative damage to expensive farm equipment. In the past, these preservatives have been applied to small-rectangular (100-lb) bales with some success, but more recent evaluations of these products in large-round bales of alfalfa hay have been somewhat disappointing. In a recent study, a commercial preservative was applied at 3 application rates (0, 0.6, or 1.0% of wet bale weight) to hays baled at 19.6, 23.8, and 27.4% moisture. Following the 73-day storage period, hays were evaluated for digestibility in growing lambs. The commercial preservative was effective at reducing heating during storage. Within the wettest hays (27.4%), there was a clear rate effect, with the 1.0% application rate suppressing heating more effectively than the 0.6% rate, but both rates offered substantial improvement relative to the untreated controls. For drier hays (23.8 and 19.6%), both application rates produced comparable suppressions of heating that were far more desirable from a production perspective than untreated hays. Evaluation of in-vivo organic matter digestibility in growing lambs indicated that digestibility was depressed in a linear relationship with heating. Therefore, application of propionic-acid-based preservatives offer some insurance against spontaneous heating and/or combustion, and offer modest benefits with respect to digestibility. However, caution is advised in interpreting these results; in this trial, bales were stacked individually (without contacting other bales). These results cannot be extrapolated to large stacks without verification by replicated research trials.