I just thought of something after checking my rats, may be you guys have some insight on these:

1. When we use rack with tubs for the breeder rats, they can't stand up on the two hind legs as high as when they're in taller bins, do you think it would affect their breeding? since the boy kind of have to get up higher to do his thing.

2. I notice many animals' growth rate kind of related to the enclosure they're in, the bigger the enclosure, the faster they grow. Are rats the same? Because after I weaned my rats 2 weeks ago, I put them is a smaller container than the tub they were in with the Mom, and I havn't notice any growth in them?

Thanks.