Goose Anser anser

Domestic geese descend from two wild species — European breeds from the greylag goose, Anser anser, Asian breeds from the swan goose, A. cygnoides — with domestication placed in Egypt about 3,000 years ago. Geese are grazing herbivores kept for meat, for fatty liver in the Landes and White Hungarian, for feathers and down, as weeders and as guard birds. Reproduction is the production bottleneck: FAO breed tables give 30 to 70 eggs a year, breeder flocks often no more than 30 to 50, laying is strongly seasonal, and one gander is mated to about four geese. Adult weights run from 3 to 10 kg across breeds, with breeder stock at 6.5 to 7.0 kg. The incubation period is genuinely disputed — 30 days in FAO's goose manual against about 33 in extension guidance — which matters when hatchers are set. Veterinarily the goose follows the avian pattern that governs both anaesthesia and aerosol disease: nine air sacs, no complete diaphragm, ventilation driven by sternal movement, one-way pulmonary airflow. Newcastle disease and high-pathogenicity avian influenza are notifiable in geese as in other birds.