The 10 percent rule, or the rule of 10s, is based on genetic variability. Whenever you hatch poultry, even offspring from the same parents, the quality of the offspring will vary. Some birds will be about average. Some will be above average, and some will be below average. This is why it’s important to cull. Only about 1 out of 10 (or 10%) will be far enough above average to consider using them as breeders.
There are variations on this rule and how it is used. It’s not uncommon for breeders to select only the top 5% of male offspring as breeders (since fewer males are needed) while keeping the top 20% of females.
And some breeders, seeking improve their flocks more rapidly or more extensively, will select only the top 1% of offspring as breeders.
How this affects you, as a potential customer, is that you can expect some variability between the birds that you order from us. If you plan on starting your own breeding flocks, let us know, and we can help you determine how many birds to order to have a good starting point.
Pen mating is where you put a rooster (or cockerel) with a group of hens (or pullets) in a single pen. The rooster will mate with any of the hens in the pen, so you’ll know the sire, but you won’t know for certain which hen the eggs came from (unless you use a trapnest). It is often used in spiral mating or clan mating breeding systems.