Temperament isn’t the only thing working in favour of Missy (Ouzles Daughter of Kong,1, if you want her formal name!). Her last litter produced a some show rats on their way to becoming champions. But I think you’ll agree it’s her temperament that makes her such a special doe!
Temperament is perhaps the most difficult thing to breed for. First, you can’t really tell what you’ve got until a rat is bit older. Does can be very, VERY active in their early months. Most bucks are sweet until 5-9 months at which time their testosterone comes into play. That is not to say that bucks are testosterone-driven thugs (okay, some are!) but that you don’t know for sure what you’ve gone for a period of time.
That’s why the NFRS recommends waiting until bucks are at least 8-9 months old before breeding them. I wait even longer! My Russian Silver rat, Pluto, is will be thirteen months before he goes in with a doe. I may breed my roan buck, Cornelius, next year because his temperament looks like it may be among the gentlest bucks I’ve ever met. His mother and two brothers are also very, very gentle so he has some likelihood of bringing that to his offspring. But he’s only 6 months old right now, so let’s wait and see, right?
While everyone agrees that temperament is critical, some people like a more active rat while some prefer the “lap rat” personality. But nobody wants a rat that bites people or is a terror to the rats, picking serious fights that cause injury to cagemates. Breeding early can mean you pass on a dodgy temperament to baby rats that are homed out to new owners before you are even aware that the father has an unsuitable temperament.
As for does, you have to expect them to be zippy and active, but the question is whether they are being active because they are skittish or because they are excited about being alive (and with you!).
Missy uses me as a climbing frame and a shoulder to perch on just like any rat. However, her superpower is being a “lap rat”, too, after she’s had a little time to wander. I’ve had a few does that like to sit like this for long periods having their ears stroked and all my does are very friendly (one leaps from the cage onto my shoulder when I open the door!), but Missy is extra sweet and I hope she passes that onto her young.
Are there any guarantees? No. Epigenetics come into play. That is, not everything about the genetics of a rat result in a particular temperament. A 2004 study at MGill University showed that the way in which mother rats take care of their babies affects the temperament of the offspring. “Mother rats spend a lot of time licking, grooming, and nursing their pups. Others seem to ignore their pups. Highly nurtured rat pups tend to grow up to be calm adults, while rat pups who receive little nurturing tend to grow up to be anxious…Through her licking behavior, a mother rat can write information onto her pups’ DNA in a way that completely bypasses eggs and sperm. In a sense, her nurturing behavior tells her pups something about the world they will grow up in. Mom’s behavior actually programs the pups’ DNA in a way that will make them more likely to succeed.” (Genetics Science Learning Centre).