I had a guitar that went through strings like crazy. I upgraded the saddles to ones that have graphite inserts where the strings contact them and the problem went away. You should have a look at your bridge, nut, any string trees, and tuners to see if you have burrs as someone mentioned. Also be careful not to kink the strings when wrapping them on the tuner. If you're still breaking a lot of strings, you might need to adjust your technique to something less violent. I do a bit of slapping (not tons) and haven't broken a bass string in many years.