Efficacy of Pediococcus pentosaceus for alfalfa forage exposed to precipitation during field wilting

The objective of the current study was to determine the preservation potential for an inoculant containing two strains of Pediococcus pentosaceus for forage that had been exposed to precipitation during the wilting phase. Forage was exposed to 26.4 mm precipitation and moderate drying conditions prior to being baled at 20–25% moisture without (Wet) or with Pediococcus pentosaceus (Wet-PP) application at the time of baling. A third hay treatment consisted of forage exposed to 27.6 mm precipitation and baled at 15–20% moisture without inoculant application (Dry). Contrary to results from previous studies with good drying conditions, application of Pediococcus pentosaceus at a rate of 105 cfu g−1 forage did not reduce extent of fungal invasion during storage as determined by storage temperature, glucosamine change, post-storage visual scores and fungal populations. Two wilting trials were conducted to determine the effect of exposure to precipitation during the wilting phase on the indigenous microbial population on the surface of forage material. Forage that was not exposed to precipitation during drying had total bacteria, lactic acid bacteria and total fungal populations ranging from 105 to 106, from 101 to 103, and from 104 cfu g−1 forage DM, respectively, at the time of baling. Exposure to precipitation resulted in population ranges of 107–108, 103–105, and 104–105 cfu g−1 forage DM, respectively. Total bacterial populations increased significantly due to exposure to precipitation. Utilization of a bacterial inoculant at 105 cfu g−1 forage may not be an adequate application rate when the density of the indigenous population on the forage surface is 100–1000 times greater. Key words:Pediococcus pentosaceus, hay, storage, mold, bacteria