Ive found that with multiple males with females that usually only one male takes on the breeding role. The other male just lays about eating,drinking, and crapping, doesnt even really make a fuss. It isnt always the oldest male that takes on the breeding role.

To introduce males to eadh other I will normally put them in a seperate enclosure that neither has scent marked. Dont put in a hide/nest this will force them to sleep together. After 2 days put them back into the breeding enclosure (once it has been cleaned and bleached to remove scents). However with really only one of them doing the breeding its more productive to keep them in 1:3 or 1:4 matchings and rotate in females.

Some rats make terrible mothers. Usually its first timers ... but I have another one that just wont take care of them ... you can either foster them out (Ive had no problems) or use them. One bad thing about fostering is that it is alot of extra work on the part of the adopting mother. Mine usually have 12 that live when i give the mother an extra 6-12 I can visibly see her getting thinner and spending more time apart from the babies. You should give those females a bit more recoup time in-between litters.

As my breeders get moved around alot Ive invested alot of time and my wifes time in making them into "pets". Potential breeders are handled from day 1 to get them accustomed to being moved around. Its alot easier to do this than to try and figure out if you should go to the emergency room because a female just bit all the way to the bone.

Bryan