Oops–someone goofed. 
They threw something into the pig’s pen.     
Was it a root? No.
Was it food? No.
Was it something new to chew? 
No. It was too hard to chew.
It was a big, old screw!
A pig can’t chew a screw for food – ew!
The pig needs roots and shoots, or a scoop of pig food.