I am far from an expert on this. However, I think that CJBS accurately makes the point for this area of the country.
I believe that the effects of feeding deer in the normally frozen and snow covered areas of the country are a whole lot different than in those areas of non-frozen warmer climates in the southern part of the country.
For anyone up north, including in our area where the ground is frozen and snow covered, I would have a real hard time suggesting that anyone feed the deer in winter, unless it is done as consistently and meticulously as would be done for cattle. Plus, way too much of the cheap corn sold in this area for deer feed has been rejected as animal or human feed because of the high levels of aflatoxins.
Just my ramblings ...