more cattle than elk, more pigs than deer

and you can catch them with a bola, kill them with axe or spear. You can snare them or brain them with a .22 rifle, and the meat will feed a family for months. without people to care for them, the livestock will all be dead a week or so after shtf anyway. dog packs will run them into the fences, breaking their legs, they will die of thirst without water being pumped to them, etc. The guy claiming that animal will probably be the guy who just recently killed the real owner, you will have no way of knowing.

So, no, you do not need a 308 with which to take elk, moose, the great bears. Only Montana, Alaska and Wyoming have grizzlies anyway. it is quite easy to bait in a bear to a point near your tree stand and then brain him with a 223, if need be. you can rig up traps to snare a bear by the paw, hooked to a drag log. ditto foot snares for the elk and moose. these animals offer so much meat that you dont need to take more than 2-3 per year per family, along with a few deer, some small game and fish. If you can't get within bow and arrow range of them those few times per year, and brain them with a 223, you are no kind of hunter.