My rabbits enjoy munching on corn stalks under the snow in our garden, along with lots of other garden waste. This is our first winter with rabbits but I’d say they are hugely more adaptable than most modern rabbit owners give them credit for. I started out more worried and watching exactly what they eat. Now that I see they are fine, thriving actually, I let them sort through piles of garden and wild vegetation for what they want. They seem to eat or nibble at just about anything including things that are supposed to be bad for them.
If you read old books on livestock you see similar discussions as the one above. Today, everything is so cheap and readily available thanks to cheap petroleum that we can be very picky about feeding our animals - like only purchased hay and pellets for rabbits. Back in the good old days, people were a lot more open minded. They had to be to survive. Herbivores like cattle were fed all sorts of vegetables and grain by products (straw, turnips, etc) and chickens and pigs were fed all sorts of table scraps and meat from butchering day. Nowadays, everything is about animal ‘nutrition’. Of course the nutrition advice is often paid for by the feed companies, LOL, just like human nutrition research is funded by big food companies.
I suppose growth rates are slower on our diet, but the rabbits are healthy, happy, grow quickly, run around, provide amusement, and the difference of a few ounces or less of meat is fine with us. It is like feedlot versus pastured beef, or caged laying hens versus our home flock. We prefer pastured beef even though it has slower growth rates. We prefer our homegrown eggs to supermarket eggs.
If we want a few more ounces of rabbit meat on our buns, we can wait to butcher a few days later. All this extra vegetation is free anyway. And we have more rabbit than we can eat right now.