As you say at the end, hmct, sheep will eat good hay. Ours generally prefer hay to silage, although at some times, freshly opened silage may be very popular.
We find it best to discard silage cattle haven't eaten within 18 hours, and that sheep haven't eaten with 72 hours.
As someone said elsewhere, it's important if using a feeder to discard old silage, not to just dump the new on top.
With hay, we just feed what they'll eat at each feed, which cuts right down on wastage. When there's snow on the ground we give the sheep a little extra (over and above what they'll eat up straight away) in the morning, all spread out in a line, then when they've finished eating they lie on what's left over, which keeps them more comfortable and makes a long pan where we can feed them cake for their evening meal. (Otherwise the cake sinks into the snow and there's a lot of waste of cake.) They get a bit more hay alongside for them to eat when they've finished their cake.