Here are our average weights for babies up to 12 weeks
Week five (numbers off because of male rescue)
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
25% Fat 12% Protein
Formula for puppies
40% Fat 33% Protein