Feeding FF in below zero weather:  I gave up!  During the last month, the feed would not stay thawed long enough for them to enjoy it.  So, I cleaned out my buckets, and switched to dry pellets, with a single serving of HOT moist mash to warm them up in the morning.  That kept them going.  
Finally, this week has seen a break in the weather pattern.  I'm ready to start FF again.  However, I was not looking forward to the "wait" for the FF to "mature".  Yesterday, I started 1/2 bucket of FF.  For starter liquid, I used rinse water from my sprouting.  By THE END OF THE DAY, the contents of that bucket were percolating like a witch's brew.  Nice tangy scent to it this morning.  Moving forward, I intend to keep about 3 gallons of ferment going.  They will get one bowl of FF, in addition to dry pellets until the weather remains predictable so their whole feed regime can return to FF.