Grass Silage For The Chickens

There is this tiny little snippet in the current (August/September 2008) issue of Backyard Poultry (more about that in another post):

One of the things you can supplement your winter feeding with is "grass silage." It says this is "created by packing dried lawn grass into heavy plastic bags (do not allow any air or moisture in or the grass will spoil) and allowing it to sit until fermented." Page 31

Wonder how you know when it's fermented. This must be the yard grass version of those giant white round hay bales. Interesting!