Effect of Lactobacillus plantarum MTD1, Potassium Sorbate or their Combination on Production of Volatile Organic Compounds and Aerobic Stability of Corn Silage
Silages have the potential to contribute to poor air quality through emission of volatile organic compounds (VOC), especially ethanol. Silage additives may be useful for reducing VOC production, but few studies have evaluated them for this purpose. The objective of this experiment was to test the effects of a biological and a chemical additive on production of VOC and aerobic stability of corn silage. Whole plant corn (37.5% DM) was chopped, processed and treated with L. plantarum MTD1 (LP, Ecosyl, Ltd., Stokesly, UK) at a rate of 1 × 105 cfu/g fresh forage basis, potassium sorbate (0.1% fresh forage basis, PS), a combination of LP and PS (LPPS), or distilled water (untreated, CTRL). Forage was packed in 7.5 L bucket silos at a density of about 230 kg DM/m3, in quadruplicate, and ensiled at 21-23°C for 119 d. Silage data were analyzed by analysis of variance as a completely randomized design using the software JMP. Measurements with a headspace GC method showed that both PS and LPPS reduced (P < 0.05) production of ethanol and ethyl acetate by more than 75% below CTRL. Treatment LPPS also reduced production of three other significant VOCs: 1-propanol, methyl acetate, and valeraldehyde. Lactic acid was slightly elevated by LPPS (P < 0.01) compared to other treatments, but the concentration of acetic acid was similar among treatments. Compared to CTRL, the additives had no effects (P > 0.05) on CP, soluble CP (% of CP), ADF and NDF. Due to contaminated media, the numbers of yeasts in silage could not be accurately determined and thus are not reported. However, there was a trend (P < 0.07) for improved aerobic stability (48, 49, 169 and 218 h, respectively, for CTRL, LP, PS, and LPPS). In conclusion, a combination of L. plantarum MTD1 and potassium sorbate appears to be a very effective additive for reducing production of several important VOCs (including the most important compound - ethanol) in corn silage. Potassium sorbate alone appears to have nearly the same effect on overall VOC production.
corn silage, inoculant, volatile organic compounds