The Megapodes are a family of birds in the galliformes order. They live primarily in Australia and are notable in being extremely precocial and laying more eggs than any other bird. They build large mounds to lay their eggs in and the largest of these birds are about the size of a turkey, hence the common name Australian Brush Turkey for Alectura lathami. The eggs also contain a larger yolk on average than chickens
So given their very fast rate of maturation, and their incredible egg laying capabilities, would they be a superior livestock choice compared to the humble chicken? The culture using them in my setting has had several centuries to selectively breed them and is living in the right climate.