Old McDonald should have had corn

Why all the animals Old McDonald? I just don't get it. Is that something like having a diverse portfolio for your retirement? Because I'm getting tired of singing about your animals...ALL your animals to William while I am trying to feed him stinky peas. May I make a suggestion? Keep the cows OR the sheep. The mooing and baaaaaing here and there and EVERYwhere usually makes him smile. But, get rid of everything else. Plant some corn. Or wheat. Do something different.