Watch Out for Silage Gas!

It’s important to recognize potentially harmful silage gases. Click here to listen to Bob Charley, Ph.D., Forage Products Manager, Lallemand Animal Nutrition, explain more.

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Is it possible to have 0 concentration of lactic acid in a silage and still have a low pH? That is my experience with sugar beet leaves at the moment. What could be the reason?
Best regards.

Hi and thank you for your question,

It depends on what you consider lower pH silage but, yes, it is possible to have a lower pH (4.5-5.5) silage with little or no lactic acid detected.

It is more than likely that your silage has undergone a normal lactic acid fermentation and lowered the pH of the silage to around 4. However later in the cycle, the fermentation has been compromised. Check the pH of your silage. If it is in the range of 4.5-5-5, the chances are its undergone a secondary fermentation due to undesirable bacterial growth.

A secondary fermentation usually occurs under very specific conditions, generally wet silages are more prone to this type of fermentation and are caused by bacteria such Acetobacter and Clostridia growing in the silage. Acetobacter as the name suggests produce acetic acid and clostridia utilise lactic acid as a food source and produce a weaker acid, namely butyric. Both these acids will raise the pH of the silage (as they are weaker than lactic) but still keep it in the acidic range.

If the silage smells bad, it’s a strong indication that a clostridial fermentation has occurred and lactic acid has been converted in butyric acid (which smells bad), this can be caused by silage that has been contaminated with soil or slurry. Check the ash levels of your silage, if it is higher than 10% there a greater possibility that the fermentation has been compromised.

If yeast or moulds are visible on the surface areas of the silage, this indicates that the silage is aerobically unstable. This type of contamination is normally caused by silage that has been poorly consolidated and or has been poorly sealed in the silo. Yeast will utilise lactic but tend to raise the pH of the silage significantly to more the pH 5. Check the consolidation of the silo and make sure it was sealed correctly. Uncovered silages will normally be over very poor quality.

If none of the above applies to your silage, there is a possibility the analysis you have received is inaccurate. Many silages are by measured by NIR (near infra-red) and forages which don’t have proper calibration studies can give widely conflicting results. Again check with the analysis company.