So what's a Golden 300 hybrid duck made of anyway?

I think it's mostly Khaki Campbell...

and maybe a bit of black swedish seeing that the males look just like them 

I imagine that they breed a Khaki Campbell drake to a Black Swedish hen to get the Golden 300.  I am not sure, but this would seem to be the most likely considering the birds they sell and the appearance of the Golden 300's.  In ducks, when you breed any drake that carries the brown dilution genes to a duck that is grey or black, it is a sex-linked mating.  I'll try to remember to ask John the next time I talk to him.

I'm sure there's more to it than just crossing breeds.  They most likely selected their breeding stock based on which ducks laid the most eggs (and probably size of eggs too).  You might be able to breed ducks that looks like a Golden 300, but unless you breed really good layers, they probably won't lay as many eggs.

I think that is probably true to some extent, Duck Feeder.  I think they probably rely a lot on "hybrid vigor" though.  Just the nature of a sex-linked cross would make it difficult to selectively breed the hybrid line itself for a specific trait.  The actual bird that results (the Golden 300) is always going to be the F1 generation.  It would be impossible to selectively breed past the F1 generation because the sex-link would no longer work.  The drake has to carry the brown dilution for it to work and all the browns in the offspring are hens (just the F1's), hence hatcheries that sell sex-links usually state that it doesn't work in future generations.

Where they probably do use selective breeding for production is in the parent birds of each breed (again which I strongly suspect are a Khaki Campbell on Black Swedish).  Commercial farms like Metzers though are always concerned about production, regardless of breed.  They have to be.  I suspect that they just cross their already selectively bred breed "A" with their already selectively bred breed "B" to get the first generation hybrid that is high producing (the Golden 300).  The resulting hybrid vigor is likely what is largely responsible for the increased egg production in the F1 generation.  Does that make sense?

Editing to add- Of course, it is also very possible that it is a 3-way or 4-way cross.  For example, the black parent could be a cross between a Black Runner and Black Swedish and/or the brown parent could be a cross between a Khaki Campbell (or Chocolate Runner) and a Buff.  The cross that makes the Golden 300 though would have to be a brown drake to a black hen since that is the sex-linked mating that would result in brown hens and black drakes.  I could see that they might indeed use 3 or 4 breeds within 2 generations to get the Golden 300.  That would result in increased production.

Anybody have the Golden 300s? Or the Gold Star Hybrids from Murray McMurray? The pictures on the 2 websites are identical so I assume that they are the same. I have been thinking of getting some of these hybrids in the spring... I like the "calmer than Khaki Campbells" claim. I am also thinking about Welsh Harlequins; it seems like many people here have had great experiences with them, and they are beautiful. Some people don't like to be dependent on a hatchery to produce hybrids, but I don't think I'm going to be doing much incubating of eggs or letting mine reproduce the natural way. My partner in crime (my 9-year-old son--we egg each other on to get more ducks) has a really had time with the idea of butchering the "extra" males you get from straight run hatches. (Sending turkeys and chickens to freezer camp he can handle, but not his dear ducks!) But we don't want a lot of drakes around fighting with each other and harassing the hens either, so we are pretty much stuck with buying sexed ducklings from hatcheries. We have a few Cayugas and Rouens and a Runner around for variety, but the majority of the flock are Khaki hens. We plan to expand my son's little egg-selling business next year, so we'll be getting a couple dozen more layers in the spring. Just haven't decided which layers to go with. I'd love to hear from people with either the hybrids or Welsh Harlequins... how well are they laying for you, and what are their temperments like? Thanks, and a happy new year to all!

CityChicker, thanks for the lucid explanation of the genetics; it's very interesting. Do you have any idea of how they (Metzer's) might get the White Golden layers?

I have both, but they're ducklings still so I can't tell you much about the laying.  The WH are a little more laid back, the Goldens are very alert and a bit flightier.  Both breeds love to eat so much that they'll come over to you anyway, though.  Big ole boobs on my babies.  ;D

Whats a Golden 300 hybrid duck?