What do the bacteria produce that preserves the silage?

Question

What are 2 advantages of preparing silage vs. shelled corn?

Answer 1

Silage undergoes anaerobic fermentation, typically beginning about 48 hours after the silo is filled. Traditionally, the fermentation is caused by indigenous microorganisms. The process converts sugars to acids and exhausts any oxygen present in the crop material. The fermentation is essentially complete in about two weeks.
Advantages over shelled corn are it is a cheaper source of a more complete feed. Also it is a safer feed to start feeding than shelled corn.

Answer 2

I'm going to guess lactic acid.