We ensilaged alfalfa at 23-25% dry matter in plastic bags. The plastic bags were bloated in first two days of ensilage. Can we have unspoiled ensilage after 60 days?
Grass and Maïze Silages are preservation forms of these forages at low pH after lactic acid production. Of course, conditions of pH and dry matter must be met. This preservation is made for months and not weeks. This year in Brittanny we keep 12 months maize silages of very good quality.
Even if you do not read French in détails you can have information from this Anses 2004 report https://www.anses.fr/fr/system/files/ALAN-Ra-ensilage.pdf