It's going to be quite some time until humans weigh 55 tons, but if you interpret the graph like people pitching to investors like to, we'll get there.
Measured in whole-population calorie throughout, is there a more successful species than cattle? They even managed to breed (in their own passive, patient way) a large group of their bipedal accomplices into greater compatibility/dependence.
I'm picturing several classic movies remade from the cows' perspective. Logan's Run would be the obvious choice, but I could also see a bovine Charlton Heston shouting You've gotta tell 'em! BEEF IS COW! We gotta stop them! Somehow! Listen! Listen to me… MOOOOOO!!
Chickens 34 Cattle 560 Sheep 70 Ducks 2 Pigs 75 Total 741 (animals)
Humans 420
Looks like there are nearly two measures of livestock weight for every one of humans.