Seramas can be tough to hatch. I'm certainly no expert, but I have hatched a few. IME, they usually hatch on day 18-19 of incubation. I have "peeled" a few, for some reason, an unusual percentage of mine have wound up coming out of the wrong end of their eggs. Sometimes I have had very good results (with my very first "home grown" Serama eggs, all 7 made it to "lock down," and 6 hatched) at other times, not so good. Broodies generally do much better than I do with the Serama eggs. I suspect that some of my failures may have drowned in the egg; I wonder if the tiny egg size may play a role, too. I currently have a small hen that lays surprisingly large eggs; I'm going to watch to see if her larger eggs have a higher success rate.
The lethal gene in Seramas comes from the Japanese Bantam that is part of the Serama's ancestry. The short leg gene is desirable in Japanese, but the Serama breeders are trying to breed it OUT of the Serama. If both of the parent birds had undesirably short legs, it could factor into the low hatch rate, but otherwise, it shouldn't be an issue.
I don't know about the lifespan; most of the Serama deaths that my flock have suffered came from a predator or disease. I can say that 2 of the first birds that I bought are at least 3 years old now, and still very lively.
The lethal gene in Seramas comes from the Japanese Bantam that is part of the Serama's ancestry. The short leg gene is desirable in Japanese, but the Serama breeders are trying to breed it OUT of the Serama. If both of the parent birds had undesirably short legs, it could factor into the low hatch rate, but otherwise, it shouldn't be an issue.
I don't know about the lifespan; most of the Serama deaths that my flock have suffered came from a predator or disease. I can say that 2 of the first birds that I bought are at least 3 years old now, and still very lively.