Variations of geese under domestication

Man has been in interrelationship with wild water fowl for thousands of years. Yet, in that time, only two species of wild geese have been domesticated (13.3% of all true geese); the Greylag goose (Anser anser) in the fourth millennium B. C. and the swan goose (Anser cygnoides) in the second millennium B. C. From these two species, numerous breeds (181) have been developed. Compared to other domestic animals, the goose has varied less during domestication, aside from a few modifications in appearance, reproductive traits, internal organs and behaviour. It has increased in body weight, and hence became a non-migratory bird. Compare to the greylag goose (gander 2.8-4.1 kg, goose 2.5-3.8 kg body weight), the body weight of the Toulouse gander has increased by 331-421%, and the Toulouse goose by 286-364%. The African goose developed higher body weights (gander by 285-362%, goose by 292-311%) compared to the weight of the swan goose (gander 3.5 kg, goose 2.8-3.5 kg body weight). Conformation traits have changed, whereby the natural grey feather colour has changed to white in some breeds. Furthermore, sexual maturity has accelerated, and prolificacy increased. Egg production of a significant proportion of the European goose breeds has increased by 600-1000% compared to the greylag goose (5-6 eggs/goose). For example, egg production of the Chinese goose has increased by 875-1200% compare to the wild swan goose (5-8 eggs/goose), and the monogamous partnership typical of wild geese has turned into polygamous matings.