The day before our first hard freeze I went ahead and cut back all the greens from the hydroponic stands. I salvaged a little for us, but ended up feeding most of it to the chickens.
We have also learned it is better to shut off the main water line that runs out to the animals. The couple of times we've forgotten or have taken a chance, a faucet or pipe will freeze and burst. Sometimes we don't see it for a few days and end up with a huge water bill.
We had one day when it didn't get above freezing all day so I had to cart water out to some of the animals. Most of it splashed out of the buckets before I got out there.