Fat pigs compete with elephants, but their noses are short. Kill one head in the whole society, enough to eat for half a year. What does that mean?

It is an extreme exaggeration to describe that pigs are raised big and fat.

This is a limerick poem during the Great Leap Forward, which reflects a kind of "grandiose style" at that time.

There is another song:

A grain of rice is boiled in one pot, and a corn pulls a cart; Sorghum stalks frame wires and cross the Yellow River with melon skins.