Introducing Rats

I was doing some math and figured out that Kasper, my albino female will be old enough to breed by the end of April, but Nibble, my berkshire female won't be old enough to breed until the end of May. Both will be about 4 months old by those times. I was wondering if it is ok to introduce Kasper to a male and begin breeding her and then introduce Nibble to the group. I know with mice its a no-no because the mice will kill each other. Will the rats be ok with re-introducing other members of the group?

Usually it's ok!

but sometimes the female rats are aggressive/bossy towards new girls, especially if they have never met before. I have 3 very bossy girls in my colony that cannot be around my albino girls. The albino girls were raised completely seperate from my other rats for 3 months before I brought them out of quarantine. Those girls have never gotten over it and will be extremely pushy to my albinos, sometimes biting them.

Mine is a pretty extreme case, and for best introductions you will want them to meet each other while they are still young. Do it in a fresh clean tub/cage that no one has been in.

I think you'll be fine honestly. Just a word of caution, you should always quarantine new rats in a different room, best as far away as possible. They can spread some very contagious viruses and other illnesses including parasites.

Well Kasper and Nibble were bought together so they are in the same cage. They cuddle, groom each other, and play. I was just wondering if it was going to be an issue to seperate them and then reunite them. I'll have to seperate them because Kasper will be old enough to breed a month before Nibble will.

There really shouldn't be any major problems with that. Actually though if the first female has been with the male for a couple of weeks or so, she'll likely be pregnant and ready to be set up to deliver a litter by the time the month has passed for the smaller female to reach breeding weight anyways. I rarely have problems with any of my rats, male or females, being shifted around. They might scuffle a bit to remind everyone who is boss of the enclosure but it's rarely more than that.

I do find that if you are concerned about rats getting along that it helps to schedule the introduction for cage cleaning day. Dump and clean the enclosure, add in fresh water, dry food and a treat type food and then the rats. Since no one has their own scent laid down already, and there is loads of food and treats to focus on, there's rarely time or concern about fussing with each other much. If they do scuffle too much, just rap the enclosure, give them a good holler to knock it off and they get the point pretty quickly that serious fighting isn't allowed by the dominant rat (that being me LOL).

Thanks to both of you! :D