Choosing your keepers in isolation

How do you know, if you have no feedback from other breeders and judges at shows, if you’re choosing the right keepers in your litters? Well – you don’t. Even during shows you don’t, the judges rarely agree with your own prefences! You can only go with your gut, but there are things you can do to help you learn. Look at your rats and look at photos of rats online, see what you like, see what you don’t. You can’t spend too much time looking at rats for comparison points of view.

Remember that the standard mainly describes a very pleasant rat to look at, so if you have eyes and like looking at rats, most people can pick out a rat that is significantly nicer than another with no training. In fact, I don’t think you can train this – you either have an eye for a good rat or not. Judge’s training doesn’t teach you how to recognise good type, it teaches you how to put what you know about rats into words. The actual learning about type is something that you should do before you do judge’s training.

Pick your kittens up with your eyes closed, and see how they feel in your hands. This teaches you about body tone, muscle tone, overall type. Can you feel how some feel more solid, some have more length? Feel around their shoulder with your thumb and forefinger – feel how some have more shoulder than others. Feel the smoothness and length of their fur, run your hand down their back and feel the curve down the spine into the tail. Hold the tail in your hands and brush down it. Repeat this with each rat, feel the differences and work out what you like, and what you don’t. Now compare each aspect to the standard (if you have not memorised the standard you can open your eyes for that bit). None of your rats will meet the standard exactly but can you decide which ones are best in your view? Even if you can’t explain why in words (that’s what judge’s training teaches you), I bet you have an idea what you like by now from a standards point of view.

The one caveat I’d make to this is one mistake that novices (and – well, some people who should know better) often make with regards to heads. The standard calls for a long head, but firm fleshed and clean. This is difficult, and many people end up with long narrow heads (which aren’t attractive), or end up breeding for short heads (which look wider, and are easier to breed). Short heads are hard to breed out so be careful you select against them. Read your standard (then read it again then look at a rat then read it again).

Colour and markings are harder to do in isolation but doable. For colours, sometimes there are several shades and you need to pick what you prefer for breeding, so you may want to refer to the standard here. Can you visualise what the standard is asking for? Can you see how yours differ, or what you’d like to improve? What makes you like that colour or marking? No two judges will ever agree on what is perfect so you as a breeder are in charge of presenting what you think is closest to perfect possible, and persuading the judge that your particular shade of (whatever) should win because it’s just so good.

By the time you’ve had two or three litters in a line, you will have the confidence to pick your own kittens. Opinions from other breeder are great and I always chat rats with other local breeders, and sometimes ask what they think of my keepers, but asking for their opinions on what to keep will just result in you knowing what they value most in a rat, when the aim is to find out what you value most and make your own mark and recognisable line of rats.

When to breed, and selecting for later fertility

There is no correct age at which to breed a rat, and there are many equally valid preferences.

It was a commonly accepted truth that, at around six months, does would have their hips fuse and be more likely to die in labour. While this has some truth in guinea pigs, it’s absolutely false in rats, and so does not form a risk factor. Even so, breeding rats at 4-5 months old has advantages – the does are almost without exception fit, in their prime, and raise kittens beautifully. They recover very quickly from raising a litter. It allows you to get through generations at speed, which can be incredibly useful for test-matings, for realising the potential of outcross programs, or to reach a goal. Even breeder who often wait til later occasionally breed a younger promising doe simply out of the excitement of seeing what she will produce! It can become overwhelming though, with two and nearly three generations of rats in a year – while the rats recover quickly, it can take more of a toll on the breeder!

Most breeders breed does around 6-8 months. At this age they’re very definitely adults, they’re mature and almost invariably fertile. Often they’ll have had a chance to go to a few shows and prove their worth, but they’re still young enough that litters are an easy prospect and the does tend to do well. It’s a bit more of a relaxed pace for the breeder too, and a bit of a compromise position between the two extremes.

Some breeders choose to breed later than this, with 9-14 months being an oft-cited window. This extreme gap between generations allows breeders to gather more long-term data on a line before the next generation arrives, so it can be useful if you have concerns about a line having late-arriving issues that have proven problematic (lifespan problems, tumours, or similar), later breeding can provide a way of more easily monitoring those. As the rats get older there is more chance of infertility, and although most does cope fine with a litter, it probably isn’t ideal for the individual rat (like a 20 year old woman will normally find recovery from and child rearing easier than a 45 year old woman, even if they both are fine!).

If a line is used to being bred very early, then you may find that if you wish to breed later on, they are not fertile, as this is not something that has been selected for.

If the fertility is normally good at six months (does fall pregnant easily, give birth to good sized litters), I’d probably breed one at six months as normal, one at eight months.

If the second doe takes, favour her offspring in the next generation, and breed from those at 6/7 months and 8/9 months, and repeat, gradually pushing the age of breeding until they’re regularly fertile later on.If the second doe doesn’t take, breed from her offspring at 6 and 6/7 months … and repeat as above but maybe with smaller gaps between the early and late doe to ensure that you have more chance of fertility.

My personal preference is to breed does between 6-10 months, ideally at around 8 months. I feel this is a good compromise position between being able to get a good overview of the line and the pressures I am putting on the individual doe.

With regards to increasing fertility, I would also select towards kittens that are slower to mature – smaller, and look “kittenish” longer, and those with a racier and longer body type over the wider and shorter rats (thoroughbreds rather than draught horses) as my gut feel and experience says that they tend to become fertile later and stay fertile longer.

What is maternal aggression?

People will argue fervently about how maternal aggression is understandable to a degree, or entirely unacceptable – but we run into a huge communication issue because there’s no definition of what “maternal aggression” is, and so quite often people are talking at cross purposes.

The last time I got a bite from a doe with babies (not new babies – a couple of weeks old), she raced across the cage and bit me when I was nowhere near her babies – I consider that maternal aggression. She was absolutely fine before her babies, and absolutely fine once removed from them (the temperament of her kittens was, and remained, superb). I think we would all consider that maternal aggression without much debate, and all of us would be happy to consider that undesirable behaviour in a doe.


The edges is where it gets more murky. I’d never even consider putting my hands under a doe with new kittens to yank her kittens out from under her – it just wouldn’t occur to me as a respectful or appropriate way to handle a rat. Is that doe maternally aggressive? She hasn’t shown any aggression (my does generally come off the nest to get their treats, at which point I take the babies out). But if she didn’t immediately come off the nest and instead sat and fussed over her kittens and made it clear through her body language that she wasn’t comfortable leaving her newborns, I wouldn’t be concerned about that – she might just not want to right now, something might have spooked her or made her unhappy, she might just not feel like it. Some people want to be able to rip her off the babies and take them out without any unhappiness from the doe. It seems to be often a cultural thing in that different groups of fanciers consider this to be appropriate/acceptable.

The problem comes when people insist that the second example provides evidence of maternal aggression, that accepting that behaviour shows a breeder to be unethical or somehow subpar, and often insist it proves that the kittens will be bloodthirsty angry aggressive killers – rather than just accepting that different people raise rats in different ways, and all of us are perfectly capable of producing perfectly fine rat kittens. If you tell me that a doe who gives me a warning nip if I reach under her to take out a newborn pinkie is evidence of poor temperament in a line, I’m going to have to ignore what you’re saying because the thousands of kittens I’ve produced from does like this with perfectly sound temperaments proves that your hyperbole is wrong. You’re fine to not want to breed from does like that yourself, of course – but it’s silly to point to the probably hundreds people successfully doing something (for example – 99% of the UK fancy, who would consider someone getting a nip from a new mother as they reached under her to have got what they deserved) and tell them it’s impossible.

Equally, if you feel that behaviour from a doe is not desirable and want to select away from it, that is an entirely reasonable aim to have, but not all breeders will consider that a priority area for selection or even a necessary area for selection, and all of those viewpoints are equally valid to hold.