'May I urge you to consider my liver?' asked the animal

Would it be unreasonable to expect that evolutionary forces will ultimately make chicken want to be eaten? By us? How do we know that is not already the case?

In a way that is different from other predator-prey relationships, it seems reasonable to assume that human beings have the capability to ensure the proliferation of a species which isn't on the brink of extinction (think poultry). The devices of modern science can ensure a rate of growth of these species, which would far exceed what would be possible in an uncontrolled environment. Certain genes would thrive; Prof. D nods.

Arthur: I just don't want to eat an animal that's standing there inviting me to. It's heartless.
Zaphod: Better than eating an animal that doesn't want to be eaten.