I have a similar situation. My cows are used to rotating to nice green 10" tall grass most of the time since May.  Well, being October in WI they are in a pasture that still has some grazing but it's more work cleaning up along the fence under the electric wire on standoffs and maybe eating stuff less attractive than they are used to.

They've been bawling like yours when they see me for a couple days wanting me to move them but then go back to grazing.  I did put out a bale of year and a half old (wrapped) hay in a ring to make sure they have enough but basically when they get hungry they will be less picky. I just keep an eye on their condition - don't want them getting thin going into winter. I watch their ribs - never want to be able to see ribs on my cows (= BCS 5 to 6).

In your case though, be careful about feeding them green, wet, unensiled lower stalks this time of year as nitrates collect in the lower stalk in the fall and can lead to nitrate poisoning. Depends on the mix of stalks to husks etc. It's different if the lower stalks are brown.

BT lower stalks are also just plain tough. Good luck.

Jim at Dawn