The problem with breeding rats with an entirely unknown genetic history, is that you pretty much have to keep several generations until they die, simply to identify any problems in their line. So it'll be another year or 2 years before you'd ever really begin to know if there are any problems.
Your best bet, if you really want to invest in making a new line, which may never work out and years of work be wasted, is to not breed them when they are immediately able to breed. Wait until they are getting around 9 months or so and breed then, so you aren't breeding as many litters. They'll all be older and you'll have fewer to take care of in the long run and it'll help you figure out if there are any genetic problems.
I would invest in good breeding stock from a reputable breeder. That way part of the work is already done and you are less likely to end up with serious problems in the line.
Your best bet, if you really want to invest in making a new line, which may never work out and years of work be wasted, is to not breed them when they are immediately able to breed. Wait until they are getting around 9 months or so and breed then, so you aren't breeding as many litters. They'll all be older and you'll have fewer to take care of in the long run and it'll help you figure out if there are any genetic problems.
I would invest in good breeding stock from a reputable breeder. That way part of the work is already done and you are less likely to end up with serious problems in the line.