@mischievoustomato @anemone The person who wrote it must have 0 knowledge of chickens.

They live off of anything, and lay on average almost one egg per day. They don't require complex accomodations, and at industrial farming scale the only really necessary veterinary cost is when you need to make sure they're not spreading something contagious, otherwise they are so plentiful when they get sick or injured they are just cheaper to replace.

It absolutely makes sense that it would be one of the cheapest source of animal protein. Like, easily.