Breeding Rats

Why do you want to breed rats?

Think carefully about breeding your rats. Why do you want to breed them? It can be hard to find homes for up to 15 or more rats and you could easily be left with many offspring who have grown up too much for people to want to buy. Before you decide to breed, try and figure out whether you have an outlet for the babies. Pet shops can be a good outlet, but BE CAREFUL. Many pet shops don’t care who buys the rats, and will sell to people who can’t/won’t care for them properly, or to snake owners as food. If you want to sell them privately, you will probably need to line up homes long before the litter is born, or failing that, advertise a heck of a lot. Bringing new rats into the world is no joke, it’s not something one should do without a lot of thought.

Selecting the parents.

If all you want to do is have a litter once just for the experience, you can probably find a rattery or friend who has a male to mate your female to. However if you want to get into selective breeding, it’s a good idea to brush up on your basic genetics knowledge so that you can predict litter outcomes and select males and females that will produce the colours and markings that you want. A great site on basic genetics can be found here. Rat associations such as AusRFS (Australian Rodent Fanciers Society) usually encourage their members involved in breeding to colour breed (breed by genetics to produce better coloured or marked offspring).
The males and females that you choose to breed should be good representatives of their colour/markings. It is imperative that they are healthy and of sound personality.
Don’t breed females for the first time who are older than 8 months as they may have extreme trouble in the actual birthing because their pelvic bones fuse into position at this age. At the other end of the scale, females should be about 5 months old before they are bred. This ensures that the females are big enough and old enough to cope with the demands of a litter.

Mating the ratties

Female rats come on heat approximately once every 5 to 6 days. It is best to leave the female in with the male for about two heat cycles to ensure that she will be pregnant. Never put a female in with more than one male as the males will engage in vicious fights. Once you can see that the female is pregnant, put her in a cage on her own. Never leave the female in with the male to have her litter as she will come on heat soon after she has given birth and the male will mate with her again.

The gestation period…

Your rat will have a gestation period of 3 weeks. In this time it is possible she will grow so big that she’ll look like she swallowed a tennis ball. Closer to birthing time, she will start building The Ultimate Nest so make sure she has a lot of nest building materials such as tissues. To help her cope with motherhood physically, a little more protein should be added to her diet. I personally like giving my mummy rats meal worms – a good source of protein and the rats absolutely love them. Meal worms are usually available at pet stores.

The birth.

You will probably become aware that your rat has given birth when you hear little tiny squeaking sounds coming from behind the wall of nesting materials that mum has blocked the nest entrance with. It is best to leave her and the babies alone for a little while as she will be busy coming to terms with the fact that she has a bunch of anklebiters hanging off her. When mum comes out of her nest for a break, coax her out of the cage with a treat and put her in another room while you check on her babies. Remove any dead ones that may be there and check their general health. Try not to touch the babies as your scent on them may stress the mother. The babies will be little pink jellybean looking things (maybe with darker markings). At this age they are blind and hairless. Don’t stick your fingers into the nest if mum is in there because no matter how sweet tempered she usually is, she will be instinct driven to keep intruders out of the nest and may bite you.

Growth Chart

Birth : hairless and blind, completely dependant on mum for everything.

  • 1 – 2 weeks : fur grows in, colours and markings become evident.
  • 2 weeks : eyes open and mum goes nuts trying to control her kids.
  • 3 – 4 weeks : they start to experiment with solid food.
  • 5 weeks : wean babies and separate boys from girls.
  • 6 weeks : baby fur starts to moult.

Finding homes for the kids.

If you are breeding excellent coloured/marked rats, you may be able to sell a lot of the babies to breeders and exhibitors. However generally there will always be some left over that need homes. Most pet shops will take rats, but be wary and ask if they sell their rats to snake owners. Also check that they don’t keep their rats in deplorable conditions. If they do, don’t let them have your rats! You can also advertise on community notice boards or in the paper for good homes. Generally $10 is a fair price to charge for rats.

After weaning…

Mum needs a break! Don’t mate her again immediately. It is best to give her 4 – 6 weeks rest and recuperation time as motherhood can take a lot out of them. Keeping your rats constantly pregnant and feeding babies will only serve to shorten their lives and create weaker babies.

Sexing young rats.

It is important to know the difference between the male and female babies, especially by 5 weeks of age. By this age rats are physically able to mate and the sexes should be kept apart. Males have more space between the anus and the genitals than the girls do. You can also see the nipples on the girls at about 2 weeks of age before their tummy hair grows in.