RAT oestrus cycle

Question
I was wondering if you would be able to tell me some good web sites where i can
find some information on rat oestrus and breeding cycle.

If not could you give me some facts about it summed down ?

i need to know this for my rat breeding at school

Answer
A female rats oestrus cycle is usually every  4 to 5 days. When she goes in to heat it lasts about 12 hours. After mating the gestation period for a litter is anywhere from 21 to 23 days (21 being most common). If a male is living with the female during pregnancy he will need to be removed before the birth as the female can become pregnant almost immediately afterwards. Babies should be weaned and separated from mother no earlier than 4 weeks of age and no later than 5 weeks. At about 4 1/2 weeks to 5 weeks of age they are able to start reproducing and brothers and sisters, and sons and mother will mate.

Never breed a female rat before 6 months of age. It can be extremely dangerous. In my own opinion I feel that no rats should be bred except to reproduce offspring that are healthier, better tempered, sweeter, and more beautiful than the ones before them. A whole improvement to the fancy.