There are concerns over volatile organic compounds and the effect they can have on air quality and their potential for reducing feed intake, this study looks at options for reducing these compounds. The effects of silage additives on the production of volatile organic compounds (VOC; methanol, ethanol, 1-propanol, methyl acetate, and ethyl acetate) within corn silage were evaluated. Silage additives may reduce VOC production in silage by inhibiting the activity of bacteria or yeasts that produce them.

In the study 18.9-L bucket silos were filled with corn silage and split into the following treatments:

 1) Control, distilled water

2) Lactobacillus buchneri 40788, with 400,000 cfu/g of wet forage

 3) Lactobacillus plantarum MTD1, with 100,000 cfu/g;

4) Commercial buffered propionic acid-based preservative (68% propionic acid, containing ammonium and sodium propionate and acetic, benzoic, and sorbic acids) at a concentration of 1 g/kg of wet forage (0.1%)

5) Low dose of potassium sorbate at a concentration of 91 mg/kg of wet forage (0.0091%)

6) High dose of potassium sorbate at a concentration of 1 g/kg of wet forage (0.1%)

7) Mixture of L. plantarum MTD1 (100,000 cfu/g) and a low dose of potassium sorbate (91 mg/kg)

 

The high dose of potassium sorbate was the only treatment that inhibited the production of multiple VOC. Compared with the control response, it reduced ethanol by 58%, ethyl acetate by 46%, and methyl acetate by 24%, but did not clearly affect production of methanol or 1-propanol. The effect of this additive on ethanol production was consistent with results from a small number of earlier studies.

A low dose of this additive does not appear to be effective. Although it did reduce methanol production by 24%, it increased ethanol production by more than two-fold and did not reduce the ethyl acetate concentration.

All other treatments increased ethanol production at least two-fold relative to the control, and L. buchneri addition also increased the 1-propanol concentration to approximately 1% of dry matter.

No effects of any treatments on fiber fractions or protein were observed. However, L. buchneri addition resulted in slightly more ammonia compared with the control.

If these results hold under different conditions, a high dose of potassium sorbate will be an effective treatment for reducing VOC production in and emission from silage. Regulations aimed at reducing VOC emission could be ineffective or even increase emission if they promote silage additives without recognition of different types of additives.

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Limin Kung, Jr., Ph.D.: Email: mailto:lksilage@udel.edu