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Meta-analysis of the effects of preservatives on hay spoilage I: Chemical treatments.

M. Killerby




Meta-analysis of the effects of preservatives on hay spoilage I: Chemical treatments.
M. Killerby*1, R. White2, D. C. Reyes1, A. Y. Leon-Tinoco1, S. Rivera1, H. Paz3, J. A. Jendza4, J. J. Romero1. 1Animal and Veterinary Sciences, School of Food and Agriculture, University of Maine Orono, 2Animal and Poultry Sciences, Virginia Polytechnic Institute and State University Blacksburg, VA, 3Department of Animal and Dairy Sciences, Mississippi State University Starkville, MS, 4BASF Florham Park, NJ.

When producers are forced to bale hay above 20% moisture, large losses of DM and nutritive value, and the presence of mycotoxins can be expected. Our objective was to conduct a meta-analysis to evaluate the effects of preservatives on hay spoilage during storage. A literature search was conducted using the ISI Web of Science database where a total of 459 peer-reviewed papers were retrieved. For inclusion in the analysis, studies had to (1) be published in English language peer-reviewed journals; (2) concurrently examine untreated and treated groups; and (3) report the preservative application rate. Chemical preservatives were analyzed as a separate subset from microbial inoculants due to incompatibilities in application rate units (% vs. log cfu/fresh g, respectively). The chemical subset included 330 treatments from 50 articles. The metafor package of R statistical software was used to fit a multilevel linear mixed-effects model with response variable reflecting the standardized mean difference between treated and untreated for DM loss, sugars, and mold presence in hay samples within an experiment, within a study. Experiment and study were used as random effects. Moderators included forage type (FT: grass, legume, or mix); moisture class (MC: below 20% or above 20%); normalized application rate (AR); and preservative classification (PC). The 2- and 3-way interactions among these moderators were also tested. Final models were selected using a backward selection procedure where non-significant variables were removed iteratively if they were not involved in significant interactions. The final model suggested DM losses were significantly related to the interactions between FT and MC (P = 0.044) and between PC and AR (P < 0.001); and to the main effects of FT (P = 0.001), AR (P = 0.050), and PC (P = 0.004). A non-significant main effect for MC (P = 0.355) was also included in the model. Sugar concentration was affected by the 3-way interaction between PC, AR, and MC (P = 0.032); and by forage type (P < 0.001). Mold presence was affected by the 3-way interaction between PC, AR, and MC (P = 0.0267) and by the 3-way interaction between PC, AR, and FT (P < 0.001).

Keywords: hay, chemical preservatives, meta-analysis.

Biography: Marjorie Killerby is a veterinary scientist currently studying a Master's degree in Animal Sciences in the University of Maine, researching on the effectiveness of preservatives in hay and silage for the animal industry.