Quote fromAlternate idea: nest and stuff like that:
For chickens: we get a chicken and an egg, or a chicken and a rooster
Cows: Cow and bull
Sheep: Sheep and ram
Pigs: 2 of em
They reproduce, and we get more pigs.
  
or perhaps a trough of sorts that lures animals to your pet, and prevents them from despawning so long as it is stocked with food