|Hafner, Sasha - University Of Denmark|
|Franco, Roberta - University Of California|
|Kung Jr, Limin - University Of Delaware|
|Rotz, Clarence - Al|
|Mitloehner, Frank - University Of California|
Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/24/2014
Publication Date: 12/15/2014
Citation: Hafner, S., Franco, R., Kung Jr, L., Rotz, C.A., Mitloehner, F. 2014. Potassium sorbate reduces production of ethanols and 2 esters in corn silage. Journal of Dairy Science. 97:7870-7878.
Interpretive Summary: Volatile organic compounds (VOC) present in silage can contribute to poor air quality, and reduce feed intake by livestock. Both problems can be addressed through the use of silage additives if VOC production can be reduced by inhibiting the activity of the bacteria or yeasts that produce them. Addition of potassium sorbate at 0.1% of fresh forage mass was found to substantially reduce the production of ethanol and at least two other important VOCs, but a lower dose may actually increase VOC production in corn silage. A commercial buffered propionic acid-based product and two microbial silage additives stimulated VOC production. Regulations aimed at reducing VOC emission in corn silage will be ineffective or even increase emission if they promote silage additives without recognition of different types of additives and their effects on silage.
Technical Abstract: The objective of this work was to evaluate the effects of biological and chemical silage additives on the production of volatile organic compounds (VOC) within corn silage. Recent work has shown that silage VOC can contribute to poor air quality and reduce feed intake. Silage additives may reduce VOC production in silage by inhibiting the activity of bacteria or yeasts that produce them. We produced corn silage in 18.9 L bucket silos using the following treatments: 1) control (distilled water); 2) Lactobacillus buchneri 40788, 400,000 colony forming units (cfu) per g wet forage; 3) Lactobacillus plantarum MTD1, 100,000 cfu/g; 4) a commercial buffered propionic acid-based preservative (containing ammonium and sodium propionate and acetic, benzoic, and sorbic acids), 1 g per kg wet forage (0.1%); 5) a low dose of potassium sorbate, 91 mg per kg wet forage (0.0091%), 6) a high dose of potassium sorbate, 1 g per kg wet forage (0.1%); and finally, 7) a mixture of L. plantarum MTD1 (100,000 cfu/g) and a low dose of potassium sorbate (91 mg/kg). VOC concentrations within silage were measured after ensiling using a headspace gas chromatography method. The high dose of potassium sorbate was the only treatment that inhibited the production of multiple VOC. Compared to 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. While it did reduce methanol production by 24%, it increased ethanol production by more than two-fold, and did not reduce ethyl acetate. All other treatments increased ethanol production at least two-fold relative to the control, and L. buchneri addition also increased 1-propanol to approximately 1% of DM. 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.