Lactic acid
Definition
Lactic acid is one of the primary acids formed during the silage preservation process. It is considered a palatable acid and is a key indicator of successful fermentation. A well-preserved silage typically contains a relatively high proportion of lactic acid.
Why lactic acid matters
Lactic acid plays an important role in animal nutrition:
- It helps maintain silage quality and palatability.
- In the rumen, lactic acid is converted into propionic acid, which is then transformed into lactose, positively influencing milk yield.
Ideally, grass silage should contain about 5% lactic acid for optimal performance.
Influencing factors
Crop condition: Harvesting crops that are not too dry and rich in sugar promotes lactic acid formation.
Silage moisture: Wet silage often contains 12–15% lactic acid, which can be beneficial but may also cause problems if excessive.
Nitrogen fertilisation: Over-fertilising with nitrogen slows acidification and reduces preservation quality because proteins fuel undesirable bacteria and buffer the silage.
Risks of excess lactic acid
While lactic acid is palatable and supports milk production, too much can lead to:
- Reduced feed intake due to overly acidic silage.
- Rumen acidification, especially if cows feed irregularly.
To prevent these issues, include slow-fermenting raw materials and buffering agents in the ration.
