So many people think there isn't much difference in finding the best brassicas for deer when it comes to general seed selection. Here is a brassica trial from a couple years back showing on the right, a common brassica used in many mixes in the industry. To the left of it is a newer and improved variety that out yields and is way more palatable. You can even see there is some early consumption by whitetail deer on the more green, less diseased brassica.
Both varieties are 60 day maturity but in years where you have wet conditions, plant diseases can come into play. Grandpa Ray's uses multi graze varieties of brassicas that are newer and improved genetics. Wonder why the deer are not eating your brassicas? One reason can be plant stresses and disease, an overlooked area of food plotting.