As always, another useful and timely discussion, as I am currently thinking about my own limits as I look toward my very first hatch, for which I will set eggs soon. I am resigned to cull some at hatch or right after - that will be a whole new thing to learn (emotionally). Among the Naked Neck hatches, this would be any fully feathered babies. Folks who do more serious breeding, esp. including coloring, often discuss how it is important to grow out chickens long enough (including through the molts to see what final coloring will be), but I will likely cull as many as I can at 12-14 weeks like I did this year. Even if/when I get lots of pens set up, it's too much time and effort to have a lot growing out at the older ages (and too much noise if the boys start all crowing in chorus). Maybe one day when I retire and buy lots of land...
- Ant Farm
Culling is from the beginning and until the end. Literally. The start is not setting undersized and off shaped eggs in the incubator. Then runts and unthrifty chicks etc.
No breeder grows all of their birds, all of the way, all of the time. That would make no sense at all. If there is reason to cull them early, then there is reason to cull them early. If there is no reason, then they are culled late.
We cannot fully evaluate the type or color until they are fully developed. That is not to say that there is not a lot that can be evaluated before. Especially, once we know our birds. Once you know them especially well, you can spot many things, very early. At the same time, the more uniform the stock is, the longer it takes to tell for the majority.
When selecting breeders, be very careful not to cull your best birds. Some will surprise you late in their development. There should always be a percentage retained for the final evaluation.
You cull for many things at different times. The final selection is made once the prospective breeders are finished and fully developed. There is a point where different strains obtain their "finish". It is up to you to find when that is.