There are duck breeds today that can essentially lay as many eggs as the best egg-laying chickens. The Khaki Campbell breed, for example, can lay over 200 eggs/year, and many are claimed to produce 300 eggs/year, which is what the best egg-laying chickens produce. Also, there are duck breeds that do just fine without access to water (the Khaki Campbell happens to be one of them), so that wouldn't really be a limitation on them, either.
Ducks could easily slip into the same barnyard niche that chickens fill in OTL. It's possible that they would be slightly less efficient and productive, but I seriously doubt that the differences would have particularly important impacts on the speed of societal development.
You beat me to it. I will point out that Khaki Campbells were bred from Indian Runners in the late 1800s, which were in turn bred from Balis. The capabilities of modern breeds aren't necessarily indicative of those of heritage breeds. Goes double of White Leghorns.
Given that chickens and ducks were first domesticated in the same general area, I see no reason why a duck species wouldn't take the place of chickens in South East Asia. Spread to Europe is doubtful. There, geese were already widely domesticated. In fact, it seems that geese were domesticated independently in Egypt, Europe, and China. IMO, you lot are overestimating the importance of chickens in a pre-industrial milieu. Chickens only eclipsed other poultry when industrial agriculture practices were adopted.
Chickens are more susceptible to diseases than other poultry and are less able to protect themselves than geese. Geese can be used as
watch animals and will pull weeds (
not joking). Chickens are also the least nutritious poultry with the most boring flavour. Chickens are easier to confine, cleaner than waterfowl, and provide rousing fights to the death for the edification of all concerned. Chickens have better parenting instincts than ducks.
Don't forget guinea fowl, another galliform. I just realised that almost all poultry are either Anatidae or Galliformes. The only two expections I can think of are peafowl and ostriches.
No chicken. Ninety percent of my protein intake just disappeared.
More seriously, the Old World suffers a bit of a setback. Turkeys aren't available and I'm pretty sure it would be hard to raise ducks in Mesopotamia. Cows and horses are too valuable as a labor supply to be used as meat very often. That only leaves pigs, and I'm sure a struggling Mesopotamian farmer with stone tools is going to have a hard time during a boar into Babe, Pig in the (Sumerian) City.
No worries. Sumerians didn't have chickens anyway. They did have goats. Maybe sheep. Your point is even more invalid in light of the fact that pigs are the
second oldest domesticated animal, predating the Sumerians. Your mistake is in assuming that they were confined. Pigs have generally been a free-range domesticate until recently.