Effects of potassium sorbate and Lactobacillus plantarum MTD1 on production of ethanol and other volatile organic compounds in corn silage

Ethanol and other volatile organic compounds (VOC) are formed during ensiling, and may contribute to poor air quality and reduce feed intake by animals. Chemical or biological additives may help address these problems by reducing production of VOC during ensiling. The purpose of this study was to evaluate the effect of additives on production of nine silage VOC in corn silage, including compounds thought to contribute to poor air quality or affect feed intake (alcohols: methanol, ethanol, 1-propanol; esters: methyl acetate, ethyl acetate, ethyl lactate; and aldehydes: acetaldehyde, valeraldehyde, hexanal). Potassium sorbate, an anti-fungal additive that has shown promising results in reducing ethanol and ester concentrations (1g/kg on a fresh mass basis); a facultative heterofermentative lactic acid bacterium, Lactobacillus plantarum MTD1 (105cfu/g on a fresh mass basis); and a combination of both additives were compared to a control treatment, which received only water. Silage was made in bucket silos which were opened after 119 days of ensiling. Potassium sorbate reduced ethanol production by >70% and ethyl lactate and ethyl acetate by >65% whether or not L. plantarum was included. Other compounds were not clearly affected by either additive when used individually, but the combined treatment reduced 1-propanol and valeraldehyde. The concentration of valeraldehyde was increased by L. plantarum. Neither potassium sorbate treatment increased concentrations of any measured VOC. These results provide additional evidence that potassium sorbate is an effective additive for reducing production of ethanol and ethyl esters in corn silage. Combining potassium sorbate with L. plantarum may provide additional benefits, although the persistence of this effect for silages with higher VOC concentrations needs to be evaluated.