Must have features for a Hobby Barn?

I am looking to build a barn to house our future critters. (Milk cow, pigs, sheep , goats, storage etc) On a smaller scale I will add. Any ideas on what size has worked great for you? What features are a "must Have"? Thanks!

While a true hay loft requires special equipment to fully utilize, having an upper storage area will nearly double your usable space. More 'stuff' can be kept out of the weather, and protected from critters.

Such a design would require less square footage of ground space, which should limit what the tax man measures.

The first thing you will need to consider is how many critters of each type. How comfortable do you want them to be pen size way? I would include a loft area for up high storage of hay and feed as already mentioned. Each space will need feed & water troughs, mineral delivery might be good also. Goats will need a Hay feeder rack, water bucket or trough, mineral feeder, all wall mounted would be best. If I were going to house all these different critters in one barn, I would have it 14-20 feet wide by 30-40 feet long with a half the length loft area with two ladders (one at each end) and perhaps a block and tackle for lifting/ lowering square bales of straw and hay or bags of feed. I would give the cow at least 3 times the animal size for an indoor pen, the hogs and sheep about the same per animal space. the goats would probably be in one large area pen.