Female kittens must first become queens. When a cat becomes a queen, it means she has matured sexually and now has regular heat sessions. Usually this happens around 6 months of age, but it can happen as early as 4 or 5 months. At this young age, female cats are still kittens. It is unsafe for them to breed with tomcats because pregnancy can be life threatening. Most responsible breeders wait until queens are around 1 year of age before they begin mating them.
Once the queen has come of age and is old enough to be mated, the heat cycles becomes very important. This is the time when the queen's estrogen level severely increases and she becomes very restless. All she wants is to mate. She is uncomfortable until she mates or until the heat cycle finally ends. This cycle can last anywhere between 3 days to 2 weeks. Rubbing against furniture, restlessness and moaning are all tips that a queen is in heat. Male cats pick up on her cues. They can sense a queen in heat from very far away and flock for the opportunity to mate with her.
Once a breeder realizes their "of age" queen is in heat, they introduce her to a tomcat. Most breeders do this as quickly as possible to end her discomfort. She assumes the position. Her tail is raised, hind quarters up and front paws bent to the ground. She keeps her head down and displays her vulva. The tomcat mounts her and places his penis inside. The penis has barbs on it to keep it in place. He also holds the female in place with paws wrapped around her hind quarters and with his mouth, biting the scruff of her neck. Then, the tomcat ejaculates.
After the male ejaculates, he withdraws his penis. The barbs pull on the inside of the queen. She howls either out of pleasure or pain. Both the barbed penis and the biting of the neck scruff stimulates the queen to ovulate. The egg is viable for around 24 hours after ovulation. To ensure impregnation, some breeders will reintroduce the queen and tomcat two or three times during her heat cycle. Leaving them together during the entire heat cycle, however, is not advised because the mating is insatiable.