Silage is pickled pasture. When pasture is ensiled, its sugars are converted into lactic acid by bacteria. It is the lactic acid which pickles the pasture, allowing it to be preserved for a lot longer than it would have been if left in the open air.
It is impossible to produce high quality silage from low quality pasture, no matter how good the fermentation is. Both the quality of the ensiled pasture and the quality of the fermentation must be considered.
Estimate of DM% grass silage
| Squeeze Test: Break up silage 2-3cm length and roll into ball size of tennis ball, squeeze in fist for 30 seconds | DM% |
| Hands dry, sample does not stay in tight ball when stop squeezing | Over 30 |
| Sample stays in ball when stop squeezing, no juice, hands moist | 26-30 |
| A little juice runs out with difficulty | 21-25 |
| Juice runs out easily | 18-20 |
Interpreting pasture silage analysis
| Factors measured | High quality fermentation | Low quality fermentation | Interpretation |
| pH | 3.5-4.5 | 5.0-6.0 | A low pH prevents unwanted butyric fermentation. |
| Ammonia N (% of total N) | 5-10 | 20-30 | Low values indicate minimal breakdown of protein in silage usually due to rapid fall in pH to a low level in silage. |
| Lactic Acid (% of DM) | 8-12 | 0.1-1 | High concentrations indicate well preserved silage. |
| Butyric Acid (% of DM) | 0.1-1 | 3-5 | High concentrations indicate poorly preserved silage. |
Time to ensile grass silage (days to when can be fed out)
| % DM | Days to ensile with inoculant | Days to ensile without inoculant |
| 20 | 4-7 | 8-14 |
| 30 | 4-10 | 14-21 |
| 40 | 4-10 | 20+ |
| 50 | up to 14 | up to 30+ |
Note: Need to use crop specific inoculant i.e. grass inoculant. Lower the DM the quicker to ensile but more risk of low quality silage (compost). Higher the sugar content the quicker to ensile.