I don't know, but as someone who tried everything and ended up having to slaughter that flock I can tell you I will never feed a laying hen a food that does not contain at least 3% calcium. Those that say they don't do this because #1 it's not great for the rooster, and #2 they want more protein.
Well for #1 I would say it has never harmed my rooster or anybody else's rooster that I have ever heard of. Plus my flocks are all about the girls and their health is most important. Honestly most roosters are far more likely to be killed by a preditor or replaced to keep a balanced Gene pool long before this comes into play. And if he is a free ranger it likely never will as my roosters eat bugs/vegetables so rarely even sample the layer feed.
#2 Purina game bird Layer has 20% protein if thats what you wanna run but also has 3% calcium. This is a food I plan on testing at some point as a local feed store carries a ton of it.
But consider this, there is a trend in modern society to focus very heavily on protein. I don't think it's a good idea to run high levels of protein. Keep in mind a can of tuna is 20% protein.
I believe a far bigger health issue to think about is that chickens and ducks are omnivores like us, and need some animal fats and proteins to be healthy. Feed manufacturers have removed all animal products from the feed and replaced them with soy. Soy is unavailable as a digestible nutritional support if it has been heat treated, cooked, or possibly best option, fermented.
Cheapest way I have found to add good healthy fats / animal proteins is a quality cat food. Also excellent but more expensive is a game fish food, like the kind used at a fish hatchery.