When I installed my barbed wire fence ( 1.5 miles ) I knew I would need about 26 rolls of new barbed wire. One roll = 1320 feet. The dealer gave me a deal on a particular brand. Red Shank - Ever Sharp. I found out why when installing the first roll.
The barbs are sharper than razors and never get dull. They are just as sharp today as when they were installed fourty years ago. You slip as you snake your way thru my fence - a sliced pair of jeans will be the least of your concerns.
If I ever need to roll up some of this wire - it will definitely require some form of machine system.