Short Term Barn

I have the idea to build a 3-walled, un-plastered straw bale barn for the winter, as a warm place for my Dexter and calf.  Roof would be corrugated metal on a round-wood frame.  In the Spring, the bales will be used as mulch.

We live in NW Ohio, so the land is flat as a pancake and the Winter temps range from 4 to 40 F.  We could have no snow all season, or we could have a blizzard!  

Any Advice?  What other short-term barn-building methods would this group recommend?

The strawbale will last the winter season, esp if you can keep it 1ft off the ground with a row of earthbag/stone/etc

I use large bales 800-1000lbs for this purpose each year. I make a pen for the pigs in the fall and then mulch them in the spring. I tried this with small bales and they just pushed them over.