So many people have asked me what a rat should weigh at a given age, or how much a mama should gain during pregnancy. This varies a lot due to genetics but also to environment. You have probably noticed that we often post the weights of our ratties. This is such a great resource for us. If we have an older rat that suddenly drops weight (illness in rats move so quickly) we can usually find a problem 'before' it gets chronic. It shows us that a mama maintains her weight while feeding sometimes over a dozen babies, and if a baby is failing to thrive. Over the last couple years we have randomly tracked over 36 different babies up to 12 weeks of age (and beyond) Some were 'foster', some were emergency rescues but most were born here or added here at 6 weeks. One thing we noticed, is that even with a huge litter, on average the rats catch up with their weight at 6-8 weeks with those of a smaller litter. If you would like to see the different weights of 'healthy' babies with litter size, feel free to contact us for this information.

Here are our average weights for babies up to 12 weeks 
male/female
Week one 
 19/19 grams
Week two
32/35 grams
Week three
51/59 grams
Week four
81/93  grams
Week five (numbers off because of male rescue)
110/123 grams
Week six  
151/156 grams
Week seven
209/183 grams
Week eight
271/202 grams
Week nine
292/229 grams
Week ten
320/243 grams
Week eleven
354/266 grams
Week twelve
381/283​ grams

​We rescued 2 boys at week 5, they came to our mischief weighing only 50 & 54 grams.  They were obviously failure to thrive due to their rescue home being hit by SDA (A very infectious virus among rodents) when they were only about a week old. We offered to help these boys with our 'magic potion' since they had not gained in almost 2 weeks. By week 6 they gained over 70 grams (in 1 week) and by week 7 they were holding their own with the rest of our mischief's weights. Once quarantine was over for these boys they actually became some of our largest boys.​

OCRA's Magic Potion for Weight Gain

We came up with this mixture after we had ZERO success with the Oxbow Critical Care our vet prescribed for an ill rattie. Critical Care is for herbivores, we might have had more luck with the Carnivore Care. The best thing about our mixture is it isn't something new for the rats. We offer them eggs every once in a while (They love to peel hard boiled) We are always offering them a mix of veggies and a few fruits. When they are not sick we also train them to take sugar water or diluted Torani syrup from a syringe. Such a great thing to teach them for if they do get ill they will already know the habit.  It is very hard to get them to take a new food because they are SO smart. In the wild they actually will send their weakest to test the new food to make sure they don't die if that isn't an option they will only take a tiny portion to make sure it is safe. If you grind up rat block, that they have already been eating, you should have much success in getting them to eat new foods with that mixed in.  

Here is what we do with our rat block

Take rat block (18% protein) put into a blender to make it into a fine flour type powder. It usually takes just a few seconds. Grind about 1/2 cup - 1 cup for several meals.  Melt tablespoon of coconut oil into skillet. Add yummy veggies and fruits (use shredded carrot, peas, avocado, shredded apple or even banana mashed up) Then add eggs to the skillet. (about 3-4 scrambled raw eggs) Once all in the skillet, sprinkle the powdered rat blocks into the skillet. Stir well, letting it all cook together on med/low with lid. If needed you can add a little water. When it is finished it is almost like a souffle. Offer this mixture to the rat needing a bit more  sustenance, keeping leftovers for a few days in fridge.  If they are really struggling,  we also add baby soy formula to the mix right before we feed them it becomes a soupy oatmeal texture.  In our opinion, soy formula is so much better for them than 'Ensure'  (full of unneeded sugars and dyes) or even puppy or kitten formula which many like to offer to those needing extra goodies. This Magic Potion has NEVER let us down for struggling weanlings, ill or elderly rats.

Rat Milk Composition
14.8% fat (by day 20 it drops to only 4.2%) 11.3% protein

Information from The Rat Fan Club on raising orphans 
Soy Formula 
25% Fat 12% Protein 
Formula for puppies
40% Fat 33% Protein 

We paired OCRA Aurora with OCRA CRUS Apollo this last week. We only leave them together overnight. This is the first time I have not seen them actually mate. It is a bit frustrating to not have instant confirmation but with weight observations and tracking Aurora's heat cycle I can pretty much confirm that have mated.

In Heat?
To know when a female rat is coming into or already in heat is pretty easy if you know what you are looking for.  For basic anatomy here is a link to see what I am talking about Sexing Rats. The female's vaginal opening is directly below her urethra. Many people mistake females for males because they think the urethra is a penis. Here is a picture of our Ariel, being hairless you can see her nipples (only female rats have nipples - 12 in all) you can also see her urethra. The vaginal opening is directly below that. I wish I had a better shot of it but with the link above and Ariel's picture it should help you know more about rats then you ever wanted.  When a female rat is in heat the vagina is open. Sometimes it becomes discolored, a blue or purple hue. Which often shows up in our darker rats.  When a female is not in heat, the hole is tightly closed.  With tracking our rats they seem to go into heat every 5-6 days. Usually a female in heat will also behave a bit different. If you scratch her back she may arch it. She may also be more jumpy, darting and sometimes spinning around. To tell the male she is interested, she will even stiffen her legs and lift her tail.  With our new girl, Pumpernickel, we will even be able to see her ears vibrate when she is in heat. The dumbo mutation prevents female dumbo ears from doing this. 

Courtship
It is possible for a female to get pregnant from a single mounting. However, during courtship, they will mount many times before the male can complete the act. Usually the female is in heat for about 10-12 hours at night but this is not always the case. Our EmmaOreo went into heat around 10 am. I have read, it is very important not to let your male rats 'play' with your female even if she is not in heat, the male might stimulate her to come into heat. What I find amazing, is how a female in heat is also VERY determined to procreate. Rats will usually synchronize their heat cycles. This helps them in the communal living to take care of each others offspring like many other animals in the wild.   A friend's new females actually chewed through their cage and chewed out the male (YES, it pays to watch CSI - the fragments were on the outside of the male's cage)  Both females became pregnant. My friend knew right away for one because she saw a mucus plug. It is a waxy plug in the vulva of the female. It is formed by the secretions from the males and can be visible for up to a day after mating. This prevents other males from breeding her. Like dogs, superfecundation, is one way to keep the genetics diverse within a colony.

How We Pair
​There are a couple different methods for breeding rats. We usually use our single level cage.  On the day the female goes into heat, we place them both together into the cage. Often it is immediate but we will leave them in the cage together overnight. In the morning, we put them back with their cagemates, usually without any problems. Occasionally the male is still a little amped up, so we often provide some yummy extra food as a distraction as he settles back into the boys dormitory. The second method, usually used by larger scale breeders, is a bit longer and less involved with the 'humans'.  They will place the male with one or two females for about 10 days. This method, insures that the female has had at least two heat cycles. However, it does sometimes make it difficult when reintroducing the rats back  with their cagemates. For this reason they usually keep the females in the cage or tub until after the babies are weaned. The male will need to be bathed and slowly reintroduced to his old cagemates to prevent any posturing or aggressive attacks. 

Tracking Weight
Now many of you know, I am a bit OCD when it comes to weighing our rats. This habit has come in handy for me to see that a rat has lost weight quickly over a weeks time. Might not look visible at first but if a healthy buck drops 15 grams in one week that is usually a sign that something is off. We weigh our juveniles and adult rats once a week. We weigh dams daily, starting from day of pairing. This has been a valuable resource helping us and others in knowing if there are complications, predicting how many babies, and overall just plain fun!  Once the babies are born depending on the size of the litter we will usually weigh the largest and the smallest the first few days. If we have runts we have even weighed them before and after us feeding them to insure they 'swallowed' formula. As for determining weight gain for a female. We notice right away a weight gain of 8-12 grams then slowly 2-10 grams a day during first few weeks. The last week there are usually huge daily gains. We have tracked up to a 24 grams gained in just 1 day with our litter of 18 (Spring 2015 'X-Men' Litter)! 

Is She Expecting?
As for Lil Miss Aurora, her weight has fluctuated so far. Last week before pairing her weight was 324g. The next morning it was 214g. The following days it went back up to 324g, yesterday it was 326 and today it is 330. I am tracking her heat cycle to see if she comes back in. We do hope she took last week. If not, this week we will continue with her evening 'playdates' with Apollo.

Very excited about our Marvel Line Pairing of OCRA Beast ♡ CRUS Celtic Rose. If all works we should hear the lil pip (squeaks) making their debut the weekend of 9/11/15.

We were just asked for the news on OCRA Truffles? It reminded me that I had not updated her Adventure the past two weeks. I am not sure if it was the shock, or denial that caused me to avoid the discussion. 

Once a week we weight our ratties. We do this to track their weight, watch for illness, and over all see the average weight for a rat at any given age. This is also a great tool when we are tracking weight in our pregnant females. We can tell right after a pairing if she has taken. We can also often tell right away if she has reabsorbed the litter. This also helps us guess fairly accurately how many lil pips(queaks) they will have.

This past month we were hoping to pair OCRA Aurora with Buddy Chandler of OCRA.  So we have been giving her extra goodies to get her pre-pregnant weight up to 300 grams. Most of our lines to this point have been so small we have had a hard time getting them to meet our personal goal of 300 grams.  On average the females have been 260 grams. 

Little bit of info : With each pregnancy the female will gain more weight filling out after her babies have been weaned. They usually will not stay down at pre pregnant weight rather gain 10-30 grams due to the hormones that have flowed so freely during pregnancy and nursing. 




For example:
EmmaOreo of OCRA  (our grandma) is now 334 grams from her previous weight of 297 grams.  She is still sleek looking without a belly but her head is much broader than before.  

OCRA Truffles on the other hand went back down to 314 after her last pregnancy (14 grams more than pre pregnant weight)  During the past few weeks she had actually gained over 40 grams going all the way to 354 grams!!! Panic. Concern. Confusion. That was what we all felt as we began to weigh even daily gains. We were actually worried that the boys in her last litter had matured early. Not common but still possible. We looked at dates, realizing that she would have had to hold over fertilized eggs before implantation for 8 days if she was pregnant again.  Possible again but still doubtful. 

We actually became convinced we were going to have another litter watching this weight gain. Fortunately, on Monday her weight dropped down 10 grams, and has continued daily to drop. Today she is 334 grams like her mama.  

Two possibilities: 
The first, she was pregnant and has begun to reabsorb. 
The second, she had been sneaking Aurora's extra treats we have been giving her to fatten her up. 

We will go with option two, even though the weight gain started before the extra treats - lol. Just because we cannot imagine getting so lucky again with her being healthy after her last delivery and us avoiding a serious catastrophe with her delayed delivery of her 4th baby. 

 ( I had to come back here to add something I forgot to mention about our lil side adventure. I was desperate to figure out the weight gain and ended up going back to re-sex all of the ratties in the girls cage, Especially, CRUS Ariel and OCRA CRUS Artemis, since they were the more recent additions but am happy to confirm they are ALL girls - hahah)