Preservation Index
Definition
The Preservation Index is a score that indicates how well silage has been preserved after ensiling. It provides an immediate assessment of fermentation quality and overall storage conditions.
Importance
Proper preservation is critical for silage success because it determines:
- Shelf life
- Palatability
- Nutritional value
Poor preservation increases the risk of undesirable microbes such as harmful moulds and bacteria, which can lead to reduced feed intake and issues like butyric acid in milk. Early detection of poor fermentation allows timely management actions and helps improve future ensiling practices.
Role of Lactic Acid Bacteria
Lactic acid bacteria convert sugars into lactic acid, lowering the pH and stopping harmful bacterial activity. Successful fermentation requires:
Anaerobic conditions (airtight environment)
Poor conditions favour undesirable microbes like clostridia and increase the risk of aerobic spoilage, reducing feed value.
Interpreting the Preservation Index
- Score range: 0 to 100
- Target: Above 80
The index reflects the quality of silage technique. Poorly preserved silage cannot be improved post-ensiling but can be redirected to lower-value uses, such as feeding young stock.
