I add it to mine, late summer early fall they start hitting the brassica greens then all winter they hit the bulbs. I believe it's a good addition to your brassica mix.
Purple top turnips, rape, radishes, kale is the mix, I have 2 plots one's about 3/4 acre and the other's about 1/4 acre and plant the brassica mix around the 4th of July.
I know mine will eat the radishes because I planted them in my rye, but I have a feeling it might be not be if they will eat it but when. Time will tell.
Years ago, I planted some giant kale seed that I bought from Albert Lea Seedhouse. I don't know if they sell it any more though. It grew a few feet tall and deer bedded in it. The deer started eating it in late December once the snow got a foot or so deep. By the end of winter, it was eaten down to the base. It was a great wintertime carryover food for the deer.
Take this for the limited value it holds, but I have a friend that's a farmer in my town (Central NH, not much ag, very low deer density) that was getting his kale absolutely savaged throughout our hunting season. I don't know what kind of kale it was, and I'd bet the area he was growing it in was smaller than a 1/5 of an acre, but it got blitzed.