No matter whether you are in the east or the west, supplementing protein to cows on corn stalks, winter range, or any other type of low-quality forage is getting very expensive. I'll pass on the discussion of when supplements are needed or not for the cow herd as I will assume everyone has a good handle on that.
Let's move on to more important things like cost. The table below shows the approximate crude protein content, bulk cost, cost per pound of CP, the approximate amount that needs to be fed per head per day to maintain a minimum 7% CP diet for dry cows, and the cost per head per day for a variety of common protein supplements. Note of course that all bulk prices and associated price calculations are FOB orgin, freight obviously will play a big role in final destination costs.
I rounded all fed amounts to 1/2 pound increments, figuring that few folks will actually calculate out 1.3748 pounds per head per day. So if you calculate and don't get the same thing, that is why.
One other thing to note is how I priced alfalfa and alfalfa/grass. With the small amount of Supreme, Premium, and Good alfalfa left in the country as a result of demand from dairies and Texans; any alfalfa that is left for beef cows is probably home raised and is priced as such.
I did include a few oddball products that you might not normally see in a list of supplements because this year they happen to be in abundant supply and reasonably priced. Many of these products are available in North Dakota, so proximate distance will determine freight cost and ultimately feasibility.
The last thing to note is that I kept the intake and cost per head per day for licktubs at about 1.0 pounds per head per day. The reason I did that is because on average, a cow will eat 0.75 - 1.0 pounds per day on tubs and that doesn't seem to change much. Of course it depends on the brand of tub and so on, but we are just using averages here.