The female rat obviously isn't a very good mother. This could be from alot of reasons. She may hot be healthy, bad diet, inbred, poor living conditions, or over crowded conditions, over stressed, to young, etc. I would suggest looking for a couple of rat females and set them up. Don't try to breed them for several weeks, to give them time to get used to their new environment, you and regular cage cleanings. Then introduce your male. I also suggest reading up on basic rat husbantry etc, if you haven't already. www.ratsrule.com has alot of good information and links to other sites with even more information.