QUESTION: How old should my breeding rats be?
ANSWER: There are two different answers: one for females and one for males.
A male should always be well over a year old before he is mated, the older the better. This ensures that he is healthy and that he is not aggressive, both bad health and bad temper is inheritable. The only male that can safely be used as a young male is a very much inbred male, as long as his relatives are all healthy and have good temper. Example: many laboratory rats.
The general rule is to not mate your male with all your females, he may have hidden faults that show up later, and all your rat babies will be too closely related. Try using all your males that is not aggressive or unhealthy.
A female should be fairly young, never as old a year, when she delivers a litter. We have had many problems with females dying here in Sweden because they were mated at the age of over a year old. This has happened both with females that had never had a litter before, and with females that had had a litter once. I personally would never mate a female over 8 months old unless she had a litter very recently. The interval between litters for a female should be as short as humanly possible, I recommend 3 months. That means only one months of rest between litters.
The general rule is to only take one litter per female, as early as possible. If she produces extremely good baies and you need another litter, mate her again as early as possible, to ensure a safe delivery and healthy female and babies.
Copyright Eva Johansson.
Last update: 11th of August 2006.