Dairy pellets vary in content but generally have fiber, protein, minerals and nutrients for cows that their normal forage might be lacking. So it should be a good thing for deer, however, since the mix is formulated to produce milk it's probably not exactly the right mix to grow antlers, but close. You can also get pellets formulated for other animals like goats and sheep, which might be closer to meeting the nutritional needs of deer. For a while we got a local feed mill to mix up custom deer feed, which they slurped up by the hundredweight like candy, to the point that it became cost prohibitive. That mix was corn, rolled toasted soybeans, oats, molasses, pellets, etc. and our deer just loved it, probably partly due to the high molasses content. So, I'd say pellets is a good thing if you can afford it.