I have 4 hens that are around 1 year old, and they started laying 7 or 8 months ago. They laid very regularly until the last couple weeks. I am wondering when should I order new replacements for my layers? What is the average number of seasons that they lay regularly? If it helps, I have 2 barred rocks, 1 brown leghorn, and 1 black austrolorp. I just don't know if I should get chicks in the spring so they can start laying around this time next year, or will my current girls have another season or two in them before they start to slow down in their egg production? Thanks for the advice!