I believe the livestock grew far past what was planned/usable. The cows are gone, but it's not like we've left the vegetation alone for centuries to let it rea

I believe the livestock grew far past what was planned/usable. The cows are gone, but it's not like we've left the vegetation alone for centuries to let it reach it's previous levels, and it's not like the marine life can spontaneously reappear after being wiped out. It's hard to restore a destroyed ecosystem.