Gilts need to be separated from male pigs by the time the females reach 16 weeks old.
As the female starts to reach five to six months old, breeders look for certain traits in them that might indicate good, healthy litters. At this stage, the female pigs will weigh about 185 to 200 pounds (85 to 90 kg.) Gilts that are not selected for breeding at this stage are generally sold off for slaughter.
When the Gilts selected for breeding reach seven and a half to eight months of age, weighing about 265 to 290 pounds (120 to 130 kg), they are ready for breeding. The boars used need to be younger ones, as older, heavier boars may injure them.
Gilts are best raised at least in pairs; when not feasible, pig raisers advise to keep them somewhere where they can at least see and hear other animals and people in order to socialize them.