Can we make isoglosses?

[Anton]

I'm afraid the idea of a "milk goose" does not hold from the practical point of view. Milk piglet or milk calf are called that because they are so young that they still feed on their mother's milk. Their meat is delicious and practically valuable, so a specific term was derived in practice to designate that kind of product.

A goose cannot feed on its mother's milk for apparent reasons. Hence any mechanical transfer of "milk something" (in the sense above specified) on a goose would be impossible in language. One would hardly succeed in locating such construct as "milk goose" in German language, let alone "goat milk goose". Even "goat milk calf" would be problematic - again, for reasons apparent.

One may argue that it might have been peasant who gave milk to geese. Why not, if he was a successful one and had no better application for his goat milk (with its comparatively low production volume). However, where is "goat milk goose" in the language of history of agriculture? There is none.

A "very young goose"? What's that? A gosling? Who would accept goslings for yearly tax? Except for breeding, may be. But that could rather serve as render for one's landlord, not as tax to the state.