I recently got some 18 month old isa browns and was quite perturbed to find out that not only were their laying days effectively over but that they would be lucky to live past 3 and considered essentially worthless. And while I may be confusing the effects of hand-rearing with breed temperament I've really become entranced with the personality and intelligence of these birds, they're light years more evolved than the leghorn hybrids I grew up with. So I'm embarking on a project to breed a chicken that lays at maybe 75-90% of the quantity and quality of an Isa Brown (or any production red sex-link) but with improved longevity. My first consideration for a cross was one of the larger dual-purpose breeds like Australorp or Wyandotte but given they've gone out of fashion for having a much higher feed consumption to egg production ratio I thought I'd try a lavender aracauna for his smaller body-size, similar rate of maturation, vigor and climate resistance and of course the blue egg gene. Plus I'm hoping this cross will produce some silver hens that can be used in time to re-create sexlinks, either that or cross a rooster from this pairing over a barred plymouth rock to bring in auto-sexing although that would require finding some plymouth rocks bred for egg production and not exhibition which may be difficult in Western Australia. I'm also starting to suspect its the body size and early maturity itself that makes egg-laying such a lethal activity for the Isa Brown so it may be self-defeating to try and preserve these traits. Either way I currently have at least 8 eggs that have been incubating for a week now and candling ok so I'll let you know how they go but in the meantime it occurs that many others must have either deliberately or inadvertently crossed Isa Brown to a heritage bred so I'm hoping someone has more information on what to expect and the best crosses to get what I'm after. For example when crossing a breed that lays 180 eggs a year to one that lays 300+ a year can I expect the offspring to lay closer to 180, 300 or somewhere in the middle? I feel like the daughters from this cross should lean closer to their mothers in terms of egg production but that's an assumption.