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Starmouse's rat breeding blog

starmouse

previously ratikate
Artist
Team Delta
Pokédex No.
200
Caught
Jun 30, 2019
Messages
57
Nature
Impish
Pronouns
she/her
Pokémon Type
Water, Fairy
Pokédex Entry
This Pokémon is said to be scared of its own shadow. It can often be found sitting in the rain.
Hello and welcome to my blog about breeding starmice rats! :no::no::no:

I thought I would start this first post with some FAQ type thing about breeding rats and breeding in general, since I know the whats and whys are something of a mystery to a lot of people, and there are a lot of very widely-perpetuated myths about breeding. Keep in mind, this will go into some slightly sensitive topics such as "feeder breeding", but I hope you will find it interesting if you choose to read it!


Science-based approach best approach!

Great question! (Thank you, me!)

Why breed rats in particular -- because they're lovely, funny, playful, very robust and simple to care for, and social! They're cute, to boot! I've kept pet rats for many years, and they are just really cool, awesome animals.

Why breed, period -- this has a bit of a complex answer. My main drive is to select for animals that have excellent temperament and health. Poorly-bred rats are prone to health problems like respiratory infections and tumours, and can be skittish or even aggressive. My goal is to work towards the opposite of that! Happier rats, and happier pet owners.

To preface this next part, I love all animals (except hippos). I also have a pet snake who does need to eat rats, so a secondary goal of mine is to breed humanely-raised "feeders" both for him and for other people's animals. A lot of our local feeder sources have really poor conditions, so I'd much rather breed feeders myself, as I know the rats are raised with love and care and humanely put to sleep when it's time to do so. (I do not sell live rats as food; only frozen.)

Many breeders also donate rats or other prey species to wildlife rehabilitation shelters that take in foxes, raptors, and other carnivorous animals.
(Other questions to be added as I think of them!)
It's a common sentiment that breeding is antithetical to animal rescue, and that breeders are filling up shelters with their animals. This isn't reeeally true, unless you're talking about backyard breeders. Ethical breeders screen adopters to ensure they will provide a good home for their animals, and maintain a relationship and follow up with said adopters to ensure the animals don't end up in a shelter! Often, breeders will take back animals that are no longer wanted, or will help rehome them. This means their animals will not contribute to shelter overflow problems.

For example, the breeder of my pet rabbit has adopters follow an agreement such that if you were to give up ownership of a rabbit produced by her, you can either bring the rabbit back to her, or she will work with you to find a suitable new adopter.

Good breeders also strive to breed well-adjusted, healthy animals. This means they are unlikely to have aggression or fear issues that could lead to the owner giving up on them, and are unlikely to rack up enormous vet bills that could do the same.

As for "adopt don't shop" as a policy -- while I think it's great to adopt animals, I also think people should be free to exercise choice in this regard, as shelter animals are often for more experienced homes and have an unknown history (for example, around small children). This is great if you are equipped for those things, but not everyone is. Particularly for rats, which don't live very long, and which you can't really spend years training and working with like you can with a dog.

While show and "designer dog" breeding is its own can of worms, and I can't really speak to that, hobbyist and pet rodent breeders almost never break even. I can't think of a single other rat breeder* I know who makes a profit. It's just not something you do for money. (I had, um, a very large bill recently when I sent in blood samples of my rats for disease testing.)

*excepting large-scale feeder breeders, but that's apples and oranges

No, actually! Well -- mostly no.

Quick glossary brush-up -- a "line" is an inbred or line-bred bloodline of animals. To "outcross" is to pair two animals that are completely unrelated. A "recessive" gene is a gene that needs two copies to be expressed. A "mutation" is a spontaneous change in a gene that was not present in either parent.

So, I'll talk specifically about rats to begin with -- because that's what I know the most about. Wild rats, as with many animal species, actually inbreed quite often, and studies show high rates of DNA similarity between rats in a specific area. Lab rats, as well, are inbred for quite a few generations in order to produce a predictable strain (a minimum of 20 generations is needed to consider the strain "inbred"). So how can this happen without creating terrifying blond sociopaths?

The reality is, genetic replication is pretty much indifferent to whether two parents are related or not. If two parents are related, this is only meaningful insofar as recessive genes are more likely to show up in pairs in their offspring, since both parents are more likely to have the same genes. But recessive genes are not usually bad -- they're responsible for causing such innocuous things as fur colour changes. There is no higher likelihood of actual mutations occurring in the offspring of related parents, and they will generally not come out "deformed" or anything like that.

The problem with inbreeding comes when the recessives code for something dangerous, like a genetic disease. However, there are processes to breed these out of the gene pool of a line, after which it would be extremely unlikely for them to return without an outcross (the only possibility being a random mutation occurring and producing exactly the same defect, which is exceptionally unlikely and totally unrelated to inbreeding). Thus, you can have a genetically homogeneous, and yet healthy, population of animals.

I should add that recessive genetic diseases are actually pretty uncommon, and I've yet to see one.

Inbreeding is also a safer bet in rats than in "slower" species, because rats have large litters and reproduce very quickly; thus, if there's (say) a 50% chance of inheriting a deleterious trait, that still means that on average, 6 rats in a litter of 12 won't have that trait, and 3 won't even carry it. At that point, it's just a matter of finding the ones that don't carry the trait, and boom, trait gone. Or, in the wild, a matter of natural selection doing its thing.

So inbreeding isn't actively harmful -- but it can be really beneficial, too. Outcrossing is kinda like playing Russian Roulette, which is to say, if you pair two totally unrelated rats, you have only a vague idea of what you're going to get. Outcrossing can be a useful thing in some circumstances, but when you inbreed, you form a line that you (with a reasonable degree of certainty, anyway) know. You know the line tends to throw litters of a certain size, you know the babies will be calm and interested in people, you know they won't have tumours, because none of their ancestors have had tumours in 20 years, etc. Moreover, inbreeding allows you to know if anything bad is lurking in the gene pool--which otherwise would bounce around quietly until it comes out in one big surprise.

(Secondary problems occur when animals are selected too hard for "designer" traits -- like brachycephalic dogs. This is a matter of being responsible and moderate, and never selecting for traits that will cause an animal to suffer.)


Phew! That took a while to type. If you have any questions about rat breeding that aren't answered up there, feel free throw them at me.
 
Last edited:

MouseWithADinosaurTail

On cloud nine, drawing away~
Artist
Writer
Team Omega
Pokédex No.
47
Caught
Jun 15, 2019
Messages
162
Location
La La Land
Nature
Quirky
Pronouns
she/her
Pokémon Type
Fairy, Flying
Pokédex Entry
Though she often appears sweet and polite, the smell of wrong opinions may cause this pokemon to latch bite.
Oh my god. oh my gooooooood. this is the content I didn't know I needed but needed so much

Edited to add cause I realized I sohuld probably say more sdkjfhsgf: It's nice to see some positive content towards rat breeding, especially breeding for food! I'm glad it sounds like you have a very humane practice, and I expect that you treat your rats with a lot of love and care! I can't wait to see some baby rat photos. OwO
 

Bug

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Team Delta
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1
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May 13, 2019
Messages
466
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in a pile of bugs
Nature
Rash
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he/him
Pokémon Type
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Pokédex Entry
oh fuck oh shit my dots...............................................................................................................................
I saw this blog and rushed in with wild abandon. I LOVE your rat posts. And I'm very interested in how you do things, because working in a store that sells your standard feeders, well... Poor things aren't really well handled. Knowing there are alternatives and how they work will definitely help me in the long run at sticking a couple of middle fingers up at nasty breeding practices. So, thanks for sharing what you know with us!

I don't know a lot about rats due to a lack of exposure, so I hope to learn a lot and see some really cute ratties.
 

starmouse

previously ratikate
Artist
Team Delta
Pokédex No.
200
Caught
Jun 30, 2019
Messages
57
Nature
Impish
Pronouns
she/her
Pokémon Type
Water, Fairy
Pokédex Entry
This Pokémon is said to be scared of its own shadow. It can often be found sitting in the rain.
  • Thread Starter Thread Starter
  • #4
@MouseWithADinosaurTail
@Bug

Aaah thank you both of you for your super nice comments!:squiddle: gfkgl;gv I'm really happy other people enjoy this stuff too!!!
I was worried a bit about posting about feeder breeding but I'm more than happy to talk about ethical practice and such as that's a big big sticking point of mine!

Mouse -- I am dying to take some more baby rat photos, but I'm on a breeding hold right now while I wait for some lab results to come in. Which I might make a post about, come to think of it.
 

sugar heart

nono morikubo is a qt
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Team Delta
Pokédex No.
257
Caught
Jul 1, 2019
Messages
63
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346 pro
Nature
Quirky
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she/they
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Pokédex Entry
hello, i like idols.
this is the kind of content that i live for

i never knew we needed a rat-breeding thread on nuzforums until you came along, this is beautiful
 

starmouse

previously ratikate
Artist
Team Delta
Pokédex No.
200
Caught
Jun 30, 2019
Messages
57
Nature
Impish
Pronouns
she/her
Pokémon Type
Water, Fairy
Pokédex Entry
This Pokémon is said to be scared of its own shadow. It can often be found sitting in the rain.
  • Thread Starter Thread Starter
  • #7
Gosh, I'm blushing here! Thank you @sugar heart @Zorua3 for your kind feedback!

I've written another entry below with some information about a very special kind of rat.

For today's post, I've decided to go back in time... to the very beginning.

To PINKIES!

Featured, one of my rat litters. Click thumbnail for high-res version.
Quoth my dad after seeing my rats' first litter: "I thought you'd get, like, three babies, and they'd look like rats. Instead you got 13 and they look like they came from space!"


"Pinkies" (singular "pinkie" or "pink") is an affectionate nickname for the tiny, pink newborn babies of rats and mice. The pinkie may also be known as a "bean", although older baby rats with fur are also considered "beans".

So why are they pink?

You see, most rodents adopt a strategy called "altriciality". "Altriciality" refers to a state of helplessness at birth, as compared to an animal like a horse that's up and running right after it's born (this is called "precociality"). Other animals that are born altricial include cats, dogs, and humans. But rodents take it to a bit of an extreme.

Rats and mice, at birth, are so underdeveloped that not only do they have no fur, their eyes are actually sealed under their skin. For comparison, humans' eyes have the ability to fully open at around 28 weeks of pregnancy. Rats are also born with their ear canals sealed shut. Their sight and hearing are therefore very rudimentary and dull, but their sense of touch is certainly there! Any kind of stimulation or pressure on their skin will cause pinkies to squeak instinctively, in a process known as "nociception".

There are a few theoretical advantages to being born so... fetal. Because the pinkies are so tiny, birth is very easy for a mother rat. Each pinkie only takes about five minutes to exit the birth canal. As a prey species with little in the way of defense, you don't want to be stuck in a vulnerable position for too long, so being able to give birth to all your babies in an hour or two is a pretty good deal. The small size also enables big litters, which is another handy thing for a small prey species, where your offspring tend to live fast and die young. Compare this to a whale or an elephant, which almost always has one well-developed baby that grows very slowly. In general, animals that move in herds will tend to have babies that can walk along with the herd, and nesting or denning animals will tend to have altricial babies, although there are exceptions.

In addition, altriciality means a pregnant rat's body can resorb the babies if things don't seem to be going well (not much food, stressful conditions), and try again later!

A nifty thing about pinkies is they don't feel pain. Earlier, I mentioned "nociception". So, let's imagine a scenario in which you burn your hand on a hot plate. Nociception is the thing that makes you jerk your hand away. Pain is the thing that makes you wince and go, "OUCH!". The neural development of pinkies, up to about 7-12 days of age, is stunted enough that it's considered highly unlikely that they experience pain. They will squeak and wiggle instinctively to avoid dangerous stimuli and to catch their mother's attention, but the pathways that would produce the subjective and very unpleasant experience of pain just aren't formed yet.

Kind of a nice bonus for a mammal, when you spend your first few moments of life being squeezed through a little tube!

From a rat breeder's perspective, what's really cool about pinkies is you can already tell a lot of things about what the rat will look like when it grows up. If you click on the image at the top of this post, you may notice that some of the pinkies have big, dark eyes, and some seem to have just... nothing. The ones with the dark eyes will appear, as adults, to have either black or very dark red eyes, while the ones with an apparent absence will grow up to have pink eyes! The pink doesn't show because the skin is about the same value and colour.

You can also tell, from their tiny sprouting whiskers, what type of coat the rat will have. If the whiskers are straight, the baby will have a typical coat of smooth, straight fur. If they're quite curly and short, the baby may be hairless, or it may be a "rex" with curly fur. If they are wavy and blown about, the baby is likely "velveteen", a very soft, slightly curled type of fur! There are a few others, but these are the most common and most easily-identified types.

Hopefully, you've by now learned something new about the amazing and honourable pinkie!

To close off this post, I'd like to share a video of a pinkie, because they are just so cool to watch:

""

P.S.: If you're wondering what they feel like to hold, picture a 5-gram, slightly deflated grape.
 
Last edited:

Bug

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oh fuck oh shit my dots...............................................................................................................................
Pinkies are SO cute. I see a lot of hamster pinkies more than anything, and they're pretty much the same, but like a smaller jellybean. There is nothing quite like lifting a hamster house to find a little cluster of pink, wiggly babies.

So, you talked a bit about feeders, so I have to ask: do you sell pinkies as well?
 

starmouse

previously ratikate
Artist
Team Delta
Pokédex No.
200
Caught
Jun 30, 2019
Messages
57
Nature
Impish
Pronouns
she/her
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Water, Fairy
Pokédex Entry
This Pokémon is said to be scared of its own shadow. It can often be found sitting in the rain.
  • Thread Starter Thread Starter
  • #9
Pinkies are SO cute. I see a lot of hamster pinkies more than anything, and they're pretty much the same, but like a smaller jellybean. There is nothing quite like lifting a hamster house to find a little cluster of pink, wiggly babies.
They are adorable. One of my favourite things is when I go into the rat room and hear those little new pinkie squeaks. They get so darn excited when their mother even comes anywhere near them, like "milk?!? Malk?!!!"
I guess hamster pinkies would have stubby tails? I'm going to Google them now!

So, you talked a bit about feeders, so I have to ask: do you sell pinkies as well?
Feeder talk: I do. In cases of large litters, I will often euthanize some pinkies within the first few days so the mother can provide more individual attention (and milk!) to each baby. Pretty much any pinkies I euthanize are sold, although I will sometimes feed one to my snake in between full-sized meals.
 
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Obelisk

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Eccentric 'locker obsessed with Magikarp.
Is there any criteria as to which pinkies you euthanize?

Rat breeding sounds really interesting and, tbh, I'm really curious...How often do you get the odd bad rat in a litter of good ones? i.e. bad behavior or unfortunately cursed with poor health. I apologize if that question comes off insensitive or rude.
 

starmouse

previously ratikate
Artist
Team Delta
Pokédex No.
200
Caught
Jun 30, 2019
Messages
57
Nature
Impish
Pronouns
she/her
Pokémon Type
Water, Fairy
Pokédex Entry
This Pokémon is said to be scared of its own shadow. It can often be found sitting in the rain.
  • Thread Starter Thread Starter
  • #11
Is there any criteria as to which pinkies you euthanize?
Euthanasia talk: Usually I will wait a couple days to see how they are developing and euth any that are either quite small (can be a sign of failure to thrive) or have physical traits I'm not looking for, like sex or fur type. Physical traits as a criteria aren't usually my first priority at all, but with pinkies, you can't tell other factors like temperament, so if I need to euth some anyway that's how I do it.
Rat breeding sounds really interesting and, tbh, I'm really curious...How often do you get the odd bad rat in a litter of good ones? i.e. bad behavior or unfortunately cursed with poor health. I apologize if that question comes off insensitive or rude.
Not insensitive or rude at all, don't worry!

So for me personally, I'm starting with less than great rats, so it's more common for me to have a litter of mainly skittish rats with one or two better ones (which get held back for breeding). I have seen other breeders share video of litters that are mostly really confident and sweet, with one rat that is aggressive, defensive, and even kinda scary. So bad apples happen.

For health, you can get a pinkie that has problems as a direct result of the birth or that aren't genetic, so aren't distributed among the litter. One example is hydrocephalus, a condition where the head swells up with water--sometimes hereditary but sometimes just bad luck.
When they are adults, there tend to be those that are more susceptible to respiratory problems and those that are less, but that's usually more of a gradient of severity than a "one bad apple" situation. Many health parameters are complex and polygenic, so for these it's more a matter of selecting for the healthiest rats so they will trend that way over time.
 

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