tried it with the hens: it didn't work

Ferdinand the duck: Look, there's something you should know.
Babe the pig: Yes?
F: Humans eat ducks!
B: Huh? I beg your pardon?
F: Ah, most ducks would like to forget it, but the fact is that humans like to eat plump, attractive ducks.
B: Ohhh, I don't think so. Not the Boss, not the Boss's wife.
F: Oh, come on. Humans don't eat cats -- why?
B: Well, they're...
F: They're indispensable: they catch mice. Humans don't eat roosters -- why? They make eggs with the hens and wake everyone up in the morning.
B: Right.
F: I tried it with the hens: it didn't work. So I turned to crowing, and lo! I discover my gift. But no sooner do I become indispensable than they bring in a machine to do the job. Ohhhh-oh-oh, the treachery of it -- a mechanical rooster!
B: Ohhh dear me.
F: Oh dear YOU! Look, I suppose the life of an anorexic duck doesn't amount to much in the broad scheme of things, but it's all I've got.