60 % of mammals are livestock, not 60% live in factory farms
99% of US farmed animals live in factory farms, according to this random website I just found. I don't claim to be an expert, though, and worldwide is probably lower than than 99%, but I would bet you that the vast majority of livestock is factory-farmed.
Agreed though that not all livestock are factory farmed. I should have clarified.
I'll point out though that even some non-factory-farmed livestock are likely suffering. Bentham's Bulldog talks about how hens undergo severe agony:
Egg-laying hens in conventional farms endure about 400 hours (!!!!!) of this kind of disabling agony. Remember, this is agony about as bad as the worst thing that’s ever happened to you, unless you’ve had an experience as bad as being severely tortured.
(emphasis mine.)
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A seal in the 4% living in the wild may be eaten alive by a killer whale or torn to shreds by a great white shark.
That's bad, though probably not anywhere near as much agony as being boiled alive for several hours until one's death. Regardless of whether you feel morally obligated to reduce wild animal suffering, you should admit that (a) from a utilitarian perspective, it's much easier to reduce factory farm suffering, and (b) from a deontological perspective, factory farming is (collectively) our fault, whereas the food chain isn't.