The Ideal Rat Food: An Open Recipe

By Brian · 32 min read · Last saved September 15, 2026

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Public-domain example formulas, so anyone can make a better food for roof rats and fancy rats. I have nothing to sell. I would just like this food to exist.

Why I am giving this away

I do not sell rat food, and I am not going to. But I keep wishing a certain kind of rat food existed, and it mostly does not, so I am writing down what it would be and putting the recipe in the public domain. Take it, change it, improve it, and if you make it, sell it. You do not need my permission and you do not owe me anything. The only thing I am hoping for is that somewhere a better bag of rat food ends up on a shelf.

This is written so it works for both kinds of pet rat: the roof rat (Rattus rattus) this site is about, and the far more common fancy rat (Rattus norvegicus, the Norway or brown rat). They are close cousins with nearly the same nutrition, and where they differ I will point it out. If you make food for the pet trade, the fancy rat is your market; the roof rat notes cost you nothing and widen the audience.

A note for keepers, not just manufacturers: you can use this too. Most of it is beyond a home kitchen (you cannot easily make a balanced, fortified block at home, which is exactly what our feeding without a pellet page is about), but the treat formulas below are very doable at home, and the target spec tells you what to look for on a label.

Want a recipe you can actually make? Our free Rat Food Builder turns these ideas into an exact recipe, shopping list, and cost for your own rats, with a built-in safety check. Open it in natural-food mode for a whole-food mix, or treat mode for functional treats.

Is this just one keeper’s opinion? No, and that matters if you are going to act on it. There is no official nutrient standard for roof rats, so everything here rests on the published laboratory-rat and nutrition science plus years of keeping the colony, not guesswork. Every claim below links to a fuller, fully cited explainer on this site, and the cornerstone studies, with their identifiers, are listed under “The science behind this” at the end.

The one idea behind all of it: do not throw away the good stuff

A normal extruded kibble is cooked hot, pressed, and stored for months. That process is great for shelf life and consistency, and it is why a good block keeps rats healthy. But high heat and long storage also strip out or degrade a lot of what real, varied food contains: fragile omega-3 fats, polyphenols, carotenoids, some vitamins, and compounds rats evolved eating that no one even puts in.^[1][2] The whole point of this recipe is a food that keeps those things in, by being gently made and by deliberately adding back what processing usually removes. If a maker just extrudes this at high heat like any other kibble, most of the benefit is gone and there was no point.

So the single most important specification is not an ingredient. It is the processing:

• Gently made, not high-heat extruded. Bake low and slow, cold-press, or cold-form (bind without a hot cook).
• Add the fragile actives after any heat step, by coating or post-mixing, so the omega-3, the polyphenols, and the heat-sensitive vitamins survive into the bag.
• Accept a shorter shelf life. A food that still contains live omega-3 will go rancid faster than a sterile cracker. That is the tradeoff for keeping the good stuff; use antioxidants, smaller packs, and honest dates rather than pretending it lasts two years.
• Let it look like food. Because it is gently formed instead of extruded smooth, this food can show its real ingredients, flecks of seed, herb, and dried vegetable, instead of being a uniform brown pellet. That is worth doing on purpose: visible whole ingredients tell a buyer that real food went in, and they appeal to exactly the owner who reads labels. The one rule is to bind the inclusions into a complete piece rather than selling a loose muesli, because rats, like rabbits, will pick out the tasty bits and leave the balanced base, which quietly breaks the “complete” promise.

The target spec (what to hit, and why)

All numbers below come from the Norway rat (the lab rat, via the NRC and the AIN-93 diet standards)^[3][4] plus my own roof-rat keeping, because there is no published nutrient profile for roof rats specifically. So for a fancy rat these are solid targets, and for a roof rat they are the best available. Treat them as a formulator’s starting point to validate, not as gospel.

Protein and fat, by life stage:

• All-life-stages compromise: about 20 to 21 percent protein, 5 to 6 percent fat. If you make one SKU, make this.
• Growth, pregnancy, nursing: about 23 percent protein. The peak-demand groups; this is the one Norway-rat figure that clearly carries over.
• Adult maintenance: about 18 percent for roof rats, about 14 to 16 percent for fancy rats. Roof rats stay lean and active, so they do better higher; fancy rats trend toward obesity, so they are usually kept a little lower. A well fed older roof rat may still put weight on and become less active, so go by body condition rather than by age. Use animal protein and legumes rather than grain alone. Different protein sources are strong in different amino acids, so mixing them is more likely to give a complete amino acid profile than grain by itself.^[5][6]
• Senior: keep weight on. Do not reflexively cut senior protein; an older rat that is wasting needs palatable, energy-dense, easy-to-eat food more than it needs restriction.^[7]

Minerals:

• Calcium about 0.5 to 0.6 percent, with a calcium-to-phosphorus ratio between about 1.2 to 1 and 2 to 1. Keep calcium above phosphorus. An inverted ratio, with more phosphorus than calcium, is a common failure in home-mixed diets and works against bone health, which is why the target above is set the way it is.^[8][9] Keep the trace minerals to the NRC profile (a standard rodent vitamin and mineral premix does this; do not freelance it).

The things ordinary food is short on (the reason to bother):

• Ergothioneine (EGT). A mushroom-and-soil antioxidant that animals cannot make but have a transporter for, and that processed diets contain almost none of.^[10][11] It is heat-stable, so it survives processing, which makes it the easiest of these to build in. This is the flagship add. (See our ergothioneine page.)
• Betaine and taurine. Two more compounds worth adding on purpose, for opposite reasons. Plants carry essentially no taurine, so a plant-based mix has no source for it at all^[12]. Betaine is the other way round: wheat bran and wheat germ are among the richest sources measured, so the betaine in a grain sits in the parts that refining removes^[13]. (See our betaine and taurine pages.)
• A real omega-3 balance, with a little GLA. Most rat food is heavily omega-6 and short on omega-3, and the anti-inflammatory effect of omega-3 depends on the absolute amount eaten.^[14] Add a modest amount of long-chain omega-3 (or a stabilized ALA source) and a little GLA, and protect it with antioxidants. Keep this modest, not maximal (see the dilute-rat note below). (See our omega-3 page.)
• Full-spectrum vitamin E, not just alpha-tocopherol. Vitamin E is eight compounds. Most foods fortify only with alpha-tocopherol, which actually suppresses the others.^[15] Use a mixed natural vitamin E that includes the tocotrienols and gamma-tocopherol, at a sensible dose. (See the dilute-rat note.)
• Polyphenols and carotenoids from real food: berries (anthocyanins), orange vegetables and leafy greens (beta-carotene, lutein), and a little vitamin K2. These come along for free if real fruit and vegetables are in the formula rather than just grain and a premix.
• Fermented ingredients and probiotics, the way good pellets already do. Many quality blocks add a yeast culture and a prebiotic fiber (inulin or mannan-oligosaccharide), and those survive baking, so build them into the base. If you want a live probiotic, use a heat-tolerant Bacillus spore-former (such as B. subtilis or B. coagulans) and coat it on after the cook step, because fragile Lactobacillus does not survive processing. The gut benefit for rats is plausible rather than proven: the rat evidence we could find is a single antibiotic-recovery study, and it used a Lactobacillus rather than a spore-former.^[16] It is cheap and safe, though, and it is what the better foods already do. A little dried fermented soy also brings vitamin K2.
• Yucca schidigera extract, for cage odor. A small amount, around 100 to 125 ppm of the finished food, is the standard, GRAS feed additive for cutting the ammonia smell of droppings, and it is heat-stable, so it goes in the base.^[17] Be honest in the claim: the odor benefit is well documented in livestock, poultry, and aquaculture, but no rat-specific studies were found in a live PubMed search on 2026-09-06, so present it as a likely nicety, not a proven feature, and do not overdose it, since the saponins are bitter.

A dilute-rat / blonde-line caution, baked into the recipe. Blonde roof rats, and pink-eyed or albino rats of either species, can have a platelet defect that makes them bleed more easily.^[18][19] Two things on this list, omega-3 and vitamin E, thin the blood, so a food aimed at or safe for those lines should keep both modest, not megadosed, lean on GLA rather than a big fish-oil load, and is a good place to include vitamin K (it supports clotting). If you sell a “blonde” or “dilute” line, this matters; the full reasoning is on our omega-3 page.

Example formula 1: an everyday base food (block or cold-formed nugget)

Given as percent by weight of the dry mix, so you can scale it to any batch. This is the all-life-stages compromise at about 20 to 21 percent protein, with adjustments below for adult and growth diets. Validate it with a qualified formulator and a proper rodent vitamin-and-mineral premix before you manufacture; treat the numbers as a sound starting formula, not a lab-certified guarantee.

Base formula (about 20 to 21 percent protein), percent by weight:

• Grain, 45 percent: 25 percent rolled oats, 12 percent brown-rice flour, 8 percent barley flour
• Legume protein, 22 percent: yellow split-pea or lentil flour
• Animal protein, 18 percent: 12 percent dried whole-egg powder, 6 percent sardine or whitefish powder (these also supply the B12 and vitamin D3)
• Calcium, 2 percent: finely ground eggshell, close to 400 mg calcium per gram^[20]
• Rodent vitamin-and-mineral premix, 2 percent (a complete small-animal premix, dosed per its label, for the trace minerals, vitamin D3, choline, B vitamins, iodine)
• Binder, fiber, and prebiotic, 9 percent: dried pumpkin or apple, a little psyllium, and a prebiotic fiber (inulin or mannan-oligosaccharide) with a yeast culture
• Cage-odor and live-culture extras, trace: yucca schidigera extract at about 100 to 125 ppm (heat-stable, mixed into the base); and, if you want a live probiotic, a Bacillus spore-former added with the post-bake actives, never before the oven
• The actives blend, about 2.6 percent, folded in AFTER baking (doses below)

The math: the protein adds up to roughly grain 4.9 + pea 5.3 + egg powder 5.4 + fish powder 4.2, which is about 20 percent protein.^[4] Phosphorus from the grain, legume, and animal-protein flours runs about 0.75 percent, so calcium needs to be about 0.9 percent to land a Ca:P near 1.2; the 2 percent eggshell plus the premix gets you there. Re-check against your premix’s own calcium and phosphorus and tune the eggshell so the final Ca:P sits between 1.2 and 2.

The actives (the things pellets miss), per kilogram of finished mix: ergothioneine 5 to 15 mg;^[10] betaine 1 to 2 g; taurine 1 to 2 g; omega-3 (EPA and DHA from fish or algal oil) about 0.5 to 1 percent of the diet, with a little GLA (50 to 100 mg from borage or evening-primrose oil);^[14] mixed natural vitamin E 50 to 100 IU (tocopherols and tocotrienols, which also keep the oils from going rancid).^[15] These rat doses are scaled estimates; start at the low end, and keep omega-3 and vitamin E modest in a blonde or dilute line.^[18][19]

Variants: for an 18 percent adult (roof rats) or 14 to 16 percent fancy-rat mix, drop the egg powder to 8 percent (and the fish powder to 4 percent for the lower end) and add that back to the grain. For a 23 percent growth, pregnancy, and nursing mix, raise egg powder to 15 percent and fish powder to 9 percent, trim the grain to 39 percent, and bump the eggshell to about 2.3 percent to keep the Ca:P up.

Method: mix the dry components, add water or pumpkin puree to a stiff dough, press about a centimeter thick, and low-bake at 250 F (120 C) for 25 to 35 minutes until firm and dry.^[1][21] Cool fully, then fold or drizzle in the actives blend, and dust on the Bacillus probiotic if you are using one, so the fragile oils and live cultures never see the oven. Break into rat-sized nuggets; store airtight in the fridge up to two weeks, or freeze.

Example formula 2: a larger-piece functional treat (the easy win)

Want the builder to do it for you? Open the Rat Food Builder in treat mode to pick treat ingredients and get the amounts, a shopping list, and the cost.

This is the part a small maker, or any keeper, can actually do, and it solves a real delivery problem: the fragile, oily actives (omega-3, GLA, vitamin E) do not survive a high-heat block and do not scatter-feed well as powders or tiny seeds. Here they go in after baking, so they stay intact.

Ingredients:

• Rolled oats, 80 g (about 1 cup)
• Whole-wheat or oat flour, 40 g (about one-third cup)
• Cooked mashed pumpkin or unsweetened applesauce, 60 g
• Hard-boiled egg, mashed, 50 g (about 1 large egg)^[22]
• Plain canned sardine, mashed with the bone, 30 g
• Ground flaxseed, 15 g (about 2 tablespoons)^[23]
• Finely ground eggshell, 2 g (about half a teaspoon)^[20][23]
• Blueberries or unsweetened dried cranberry, chopped, 25 g (about 3 tablespoons)
• Water, 1 to 2 tablespoons to bind
• Added after baking: fish or algal oil (EPA and DHA) 4 g (about 1 teaspoon); borage or evening-primrose oil (GLA) 1 g (about a quarter teaspoon, which is roughly 240 mg of GLA if you use borage)^[24]; mixed natural vitamin E oil, about 100 IU for the whole batch, worked out from your own bottle’s IU per drop, because drops differ a lot between products

Method: heat the oven to 300 F (150 C). Mix everything except the three finishing oils into a stiff dough, adding water a little at a time. Roll into small balls, or press into a thin sheet and score into small squares, on parchment. Bake 18 to 22 minutes until just firm and lightly dry; do not brown hard.^[21][25] Cool completely. Whisk the three finishing oils together, drizzle or brush them over the cooled bites, and let them absorb for 10 minutes. Weigh the finished batch after the oils have absorbed, and divide it into roughly 3 g portions. That last step keeps the omega-3, GLA, and vitamin E biologically intact, and the vitamin E doubles as the antioxidant that keeps the fish oil from going rancid.

Yield, dose, and storage: the number of bites depends on the cooled finished weight; portion them at roughly 3 g each. Offer 2 or 3 per rat per week as a treat, not a meal. Store airtight in the fridge and use within 7 to 10 days, or freeze up to 3 months and thaw a few at a time. If a bite ever smells like paint or off fish, throw it out: oxidized omega-3 does more harm than good.

Example formula 3: a fully vegan base food (proposed)

Some keepers and makers want a plant-only food, and a vegan rat diet can be complete. But veganizing a rat food is not just leaving out the egg and the fish. There are four things a rat needs that a plant-only mix does not reliably supply, and each one has to be added back on purpose or the food is quietly deficient: vitamin B12 (absent from plant foods), vitamin D3 (plants do not make it, and an indoor rat gets little UVB to make it from light either), taurine (almost absent from plants), and the long-chain omega-3s EPA and DHA (which normally come from fish and have to come from algae instead).^[26] Handle those four and the formula below is sound. Ignore them and it is not.

Base formula (about 20 to 21 percent protein), percent by weight:

• Grain, 42 percent: 24 percent rolled oats, 10 percent brown-rice flour, 8 percent barley flour
• Legume and soy protein, 33 percent: 18 percent yellow split-pea or lentil flour plus 15 percent soy protein. The soy matters: peas are a little short on the amino acid methionine, and soy runs higher in methionine than peas do, so blending the two raises the mix’s overall amino acid score, even though neither is complete alone. Use cooked or toasted soy, never raw.
• Mushroom powder, 3 percent: dried oyster or shiitake, for umami and a natural ergothioneine contribution. Culinary mushrooms only.
• Food-grade calcium carbonate, about 1.5 percent (this replaces the eggshell, at about 400 mg calcium per gram). Tune it to land the calcium-to-phosphorus ratio between 1.2 to 1 and 2 to 1.
• A vegan-complete vitamin-and-mineral premix, 2 to 3 percent. This is the non-negotiable part. It has to supply vitamin B12, vitamin D3 from lichen (the one vegan source of true D3), choline, the B-vitamins, iodine, and the trace minerals. In a vegan diet this premix is not a finishing touch, it is what makes the food complete.
• Binder, fiber, and prebiotic, 9 percent: dried pumpkin or apple, a little psyllium, a prebiotic fiber (inulin or mannan-oligosaccharide), and a yeast culture. B12-fortified nutritional yeast helps with flavor and B-vitamins, but it is not a reliable sole source of B12, so still lean on the premix.
• The actives blend, about 2.6 percent, folded in after baking (below).

The actives, per kilogram of finished mix (all plant-sourced): ergothioneine 5 to 15 mg (mushroom extract); betaine 1 to 2 g (from beet); taurine 1 to 2 g (synthetic taurine is made without any animal product, so it is vegan, and it is essential here because plants have almost none); omega-3 EPA and DHA about 0.5 to 1 percent of the diet from algal oil (the vegan source of the long-chain omega-3s fish would otherwise provide), plus a little GLA (50 to 100 mg from borage or evening-primrose oil); mixed natural vitamin E 50 to 100 IU; and a little vitamin K2 as MK-7 from natto. Start at the low end, and keep the omega-3 and vitamin E modest in a blonde or dilute line. See our ergothioneine and omega-3 pages for the reasoning.

Method: the same as formula 1. Mix the dry components, bind to a stiff dough with water or pumpkin puree, press about a centimeter thick, and low-bake at 250 F (120 C) for 25 to 35 minutes until firm.^[1][21] Cool fully, then fold in the actives blend so the fragile oils never see the oven.

The vegan completeness check (run it, do not skip it): a plant-only base passes only when (1) B12 and (2) vitamin D3 are supplied by the fortified premix, (3) taurine is added as the synthetic active, and (4) the long-chain omega-3 comes from algal oil. Have a qualified formulator confirm the amino-acid profile (lysine and methionine especially) and the final vitamin-and-mineral numbers. Done this way a vegan rat food is complete and non-toxic. Done as a naive leave-the-meat-out, it is not.

Example formula 4: a vegan functional treat

This is the plant-only version of formula 2, and it is very doable at home.

Ingredients:

• Rolled oats, 80 g (about 1 cup)
• Oat or whole-wheat flour, 40 g (about one-third cup)^[23]
• Cooked mashed pumpkin or unsweetened applesauce, 70 g
• Firm tofu, mashed, 60 g (this replaces the egg as the protein), or 25 g soy protein^[23]
• Ground flaxseed, 15 g (about 2 tablespoons, plant omega-3 as ALA)^[23][27]
• B12-fortified nutritional yeast, 10 g (flavor and B-vitamins)^[23][28]
• Food-grade calcium carbonate, 2 g (replaces the eggshell with approximately the same amount of calcium). Sesame is not a gram-for-gram substitute for this measured calcium addition.
• Blueberries or unsweetened dried cranberry, chopped, 25 g
• Water, 1 to 2 tablespoons to bind
• Added after baking: algal oil (EPA and DHA) 4 g (about 1 teaspoon); borage or evening-primrose oil (GLA) 1 g (about a quarter teaspoon, which is roughly 240 mg of GLA if you use borage)^[24]; mixed natural vitamin E oil, about 100 IU for the whole batch, worked out from your own bottle’s IU per drop, because drops differ a lot between products

Method: heat the oven to 300 F (150 C). Mix everything except the three finishing oils into a stiff dough. Roll into small balls or press and score into small squares on parchment. Bake 18 to 22 minutes until just firm; do not brown hard.^[21][25] Cool completely, then whisk the three oils together and drizzle or brush them over the cooled bites so the omega-3, GLA, and vitamin E stay intact. Let the oils absorb, weigh the finished batch, and divide it into roughly 3 g portions. Offer 2 or 3 per rat per week. Store airtight in the fridge for 7 to 10 days, or freeze.

One completeness note for treats: a treat is judged as the daily block plus the treat combined, so the treat itself does not have to be complete. But if these vegan treats are a rat’s main protein top-up, make sure the daily base already covers B12, vitamin D3, and taurine, the three things a plant-only diet most easily misses.

A vegan-specific safety note: keep it to safe plants. No onion, garlic, leek, or chive (all toxic to rats); only culinary mushrooms (never wild-foraged, and never the poisonous or psychoactive kinds); and cook the legumes and soy, because raw beans and raw soy carry lectins and enzyme inhibitors that harm the gut. Do not megadose the fat-soluble vitamins.^[29][30] With those rules, the vegan formulas above are non-toxic.

Per-life-stage and per-line variants (the same recipe, retuned)

• Growth / pregnancy / nursing: protein up to about 23 percent, calcium toward the high end (lactation pulls calcium from the dam’s bone^[31]), energy-dense.
• Adult maintenance: about 18 percent protein for roof rats, 14 to 16 percent for fancy rats; not calorie-dense; both run best lean.
• Senior: keep it palatable, soft, and easy to eat; antioxidant-forward; go by body condition rather than by age, and do not cut the protein just because the rat is old.
• Blonde / dilute / pink-eyed line: modest omega-3 and vitamin E, GLA over a big fish-oil load, include vitamin K. (See the dilute-rat note above.)

How to form it: rat cookies and pressed blocks

A “rat cookie” and a “block” are the same thing made two ways. You mix the ingredients, bind them, form them, and dry them. The only real difference is the purpose: a treat cookie just has to be tasty and safe, while a base block has to be nutritionally complete and balanced (hit the target spec above). So the method below is one method; whether the result is a treat or a daily base depends on whether you built it to be complete.

1. Mix the dry base: ground grains, cooked-and-dried legumes, a protein (egg, insect, or fish), ground seeds, and ground eggshell for calcium.
2. Fold in the small stuff: the vitamin and mineral premix (B12 yeast, a speck of kelp for iodine, wheat germ for vitamin E and betaine) and any functional add-ins. UV-exposed mushroom powder adds vitamin D2 rather than D3, so treat it as a bonus and let the premix supply the D3.^[32] Powders only work mixed in like this; loose, they just end up in the litter.
3. Bind it: work in a binder until it holds together: a little natural peanut butter (unsalted, no xylitol), manuka honey, mashed banana or sweet potato or pumpkin, or a beaten egg. Peanut butter and honey also make it irresistible.
4. Form it: press into a tray and score into blocks, or roll small cookies or nuggets.
5. Dry it: low-bake in a low oven or dehydrate until firm, or for a no-bake version chill cold-formed cookies. Dry enough to store, but soft enough for a sore-mouthed or old rat if that is who it is for.
6. Store cool and use within a few days, or freeze.

A few add-in notes. Turmeric goes in with a little fat to absorb it, and without black pepper. Ginger and spirulina only work hidden in the mix. Nettle goes in dried or as a tea. Bee pollen mixes well with honey. Milk thistle is a liver supplement, used as an extract stirred in. Manuka honey is a good binder, and it is mildly antibacterial,^[33] so a small dab also works as a dressing on a scrape and is safe if the rat licks it off.^[34] Raw honey carries the infant botulism caution used for human babies under a year old; this page cannot point to evidence either way for rat kits, so keep it away from young kits and nursing mums as a precaution rather than as a proven rule.

The Rat Food and Menu Builder now has these binders and add-ins built in: choose “complete block or cookie” for a base, or “functional treats” for a cookie, and it keeps the balance right.

Honest caveats for anyone who makes this

• There is no roof-rat nutrient standard. Every number here is Norway-rat data or my own keeping, extrapolated. A fancy-rat food is on firm ground; a roof-rat claim should be honest about the extrapolation.
• Get a real formulator and a premix involved. “Complete and balanced” is a serious claim. Use a qualified animal nutritionist and a proper vitamin and mineral premix; do not eyeball completeness from the example proportions above.
• Rodent food is lightly regulated, which cuts both ways. AAFCO nutrient profiles cover only dogs and cats, so there is freedom here, but that means “complete” is your claim to stand behind. Be careful with health claims.
• The benefits of the cutting-edge adds (EGT especially) are promising, not proven, in rats. Do not let marketing outrun the evidence. The honest framing on every one of these is on the linked pages.
• The gentle-processing, omega-3-containing food is inherently shorter-shelf-life. Plan packaging, storage, and dating around that instead of fighting it.

The science behind this

There is no official nutrient profile for roof rats, so every number and claim here is built on the published laboratory-rat (Norway-rat) and nutrition literature, plus years of keeping the colony. Nothing here is invented. Each topic has a fuller, fully cited explainer on this site; below are the cornerstone sources, every one checked against the original.

1. Why processing strips nutrients: high-heat extrusion and long storage degrade polyphenols and oxidize the fragile omega-3 fats. This is well established in food science and is laid out with citations on our Why kibble falls short page.
2. The nutrient targets (protein, fat, calcium, calcium-to-phosphorus): National Research Council, Nutrient Requirements of the Laboratory Rat (NCBI Bookshelf NBK231925); Reeves and colleagues, the AIN-93 purified diet standard, Journal of Nutrition 1993 ^[4].
3. Ergothioneine (EGT): a diet-only antioxidant animals cannot make yet actively pull into cells through a dedicated transporter, OCTN1 ^[10]; dietary EGT raised median lifespan about 16 percent in male mice ^[35]. It is also notably under-consumed in some modern diets, and higher blood levels track with lower disease and mortality, though that association is correlational, not proof ^[11]. Full page: Ergothioneine for rats.
4. Omega-3 and the fat balance: fatty acids are dietary essentials for rats ^[36], and the anti-inflammatory effect of omega-3 depends on the absolute amount eaten ^[14]. Full page: Omega-3 for rats.
5. Full-spectrum vitamin E: vitamin E is eight different compounds, and a high alpha-tocopherol intake can suppress the others, the tocotrienols ^[15]. Discussed on the omega-3 page.
6. The blonde and dilute bleeding caveat: the blonde coat comes from the Rab38 gene, the same gene behind the fawn-hooded laboratory rat’s platelet storage-pool deficiency, so these rats bleed a little more easily ^[18][19]. That is why the recipe keeps omega-3 and vitamin E modest in dilute lines; full reasoning on the omega-3 page.
7. Calcium and eggshell: measured, finely ground eggshell powder supplies close to 400 mg of calcium per gram (Schaafsma and colleagues measured 401 plus or minus 7.2 mg per gram) ^[20], rats absorb that calcium about as well as the calcium carbonate in a supplement (Hirasawa and colleagues, a rat balance study) ^[37], and grinding your own from boiled eggs is a tested way to make a home calcium source (Brun and colleagues) ^[38]. Correction, 2026-08-17: this page used to say that eggshell supplies “about 380 mg of calcium per gram and is absorbed about as well as a calcium supplement” and credited both halves of that to Brun and colleagues. Their paper reports 2.07 g of calcium in a whole eggshell, which is about 5 g of powder, gives no per-gram figure, and does not compare absorption to a supplement. The measured per-gram figure is Schaafsma’s and the rat absorption comparison is Hirasawa’s. The calcium-to-phosphorus targets themselves are the NRC’s ^[4]. The all-natural recipes use this to correct the otherwise-inverted ratio; see feeding without a pellet for the worked math.
8. Yucca and probiotics (the production-feed extras): yucca schidigera extract is a long-used, GRAS feed additive whose ammonia-reducing effect is well documented in livestock, poultry, and aquaculture; no rat-specific studies were found in a live PubMed search on 2026-09-06, so the benefit for rats is an extrapolation, not a proven one.^[17] A typical inclusion is about 100 to 125 ppm. Probiotic and prebiotic inclusions are standard in the better pet foods; heat-stable Bacillus spore-formers survive processing or are coated on afterward, and the gut benefit for rats is plausible rather than proven; the one rat study we could find used a Lactobacillus in an antibiotic-recovery model.^[16]

Betaine and taurine each have their own evidence-and-dosing pages: Betaine for rats and Taurine for rats. Two honesty notes: where a benefit is still a promising hypothesis rather than proof in rats (EGT’s lifespan effect, for instance), the linked pages say so plainly; and because AAFCO nutrient profiles cover only dogs and cats, for rodent food “complete and balanced” is the maker’s claim to stand behind.

Public domain dedication

To the extent possible under law, I dedicate the formulas, target spec, and recipe ideas on this page to the public domain (Creative Commons Zero, CC0). No rights reserved. You may copy, change, manufacture, and sell food based on these, for any purpose, with no permission and no attribution required. I make no warranty and accept no liability; anyone manufacturing a food is responsible for its safety and completeness. If it helps rats, that is the whole point.

Frequently asked questions

Is there a recipe for the best rat food?

There is no single official one, because no nutrient standard exists for roof rats and rodent food is lightly regulated. This page gives an open, public-domain target spec and example formulas: gently made (not high-heat extruded), the right protein and calcium for the life stage, and the things ordinary kibble leaves out, like ergothioneine, a real omega-3 balance, full-spectrum vitamin E, and polyphenols from real fruit and vegetables.

Can I make my own rat food or treats at home?

A complete, balanced block is hard to make safely at home, because it needs a proper fortified vitamin and mineral premix, so for the daily base, buy a good block. But the larger-piece functional treats on this page are very doable at home, and they are the best way to deliver the fragile omega-3 and vitamin-E actives that do not survive a high-heat kibble.

What is the ideal protein level for rat food?

Roughly 23 percent for growth, pregnancy, and nursing; about 18 percent for adult roof rats, which stay lean; and about 14 to 16 percent for adult fancy (Norway) rats, which trend heavier. A single all-life-stages food lands around 20 to 21 percent. These come from Norway-rat data, so watch your own rat’s body condition more than any single number.

What do commercial rat foods leave out?

High-heat extrusion and months of storage degrade fragile omega-3 fats, polyphenols, carotenoids, and some vitamins,^[1][2] and most foods never include compounds a wild rat eats, such as ergothioneine, or use only alpha-tocopherol instead of full-spectrum vitamin E. A better food keeps those in by being gently made and deliberately fortified.

Are these formulas free to use commercially?

Yes. They are dedicated to the public domain under Creative Commons Zero (CC0): you can copy, change, manufacture, and sell food based on them, for any purpose, with no permission and no credit required. There is no warranty, and anyone who makes a food is responsible for its safety and completeness.

Does this apply to fancy pet rats or only roof rats?

Both. The nutrient targets are Norway-rat-derived, so they fit the common fancy (Norway) rat directly and are the best available guide for a roof rat. The main difference is body type: fancy rats trend heavier and are usually kept a little lower on protein at maintenance, while roof rats stay lean and do better on the higher end.

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This is care and design information from one keeper, not veterinary or formulation advice. Validate any food with a qualified animal nutritionist before you make or sell it.

Special needs: for how this fits feeding a rat with a health condition, see Feeding a Rat With Special Needs.

References

• [1] Tran QD, Hendriks WH, van der Poel AFB. “Effects of extrusion processing on nutrients in dry pet food.” Journal of the Science of Food and Agriculture 2008;88(9):1487-1493. DOI.
• [2] Lin S, Hsieh F, Huff HE. “Effects of lipids and processing conditions on lipid oxidation of extruded dry pet food during storage.” Animal Feed Science and Technology 1998;71(3-4):283-294. DOI.
• [3] National Research Council (US) Subcommittee on Laboratory Animal Nutrition. “Nutrient Requirements of Laboratory Animals: Fourth Revised Edition, 1995.” National Academies Press 1995. source.
• [4] Reeves PG et al. “AIN-93 purified diets for laboratory rodents: final report of the American Institute of Nutrition ad hoc writing committee on the reformulation of the AIN-76A rodent diet.” Journal of Nutrition 1993;123(11):1939-1951. PubMed.
• [5] Koo WW, Lasekan JB. “Rice protein-based infant formula: current status and future development.” Minerva Pediatrica 2007;59(1):35-41. PubMed.
• [6] Li P, Wu G. “Composition of amino acids and related nitrogenous nutrients in feedstuffs for animal diets.” Amino Acids 2020;52(4):523-542. PubMed.
• [7] Barbé C, Salles J, Chambon C, Giraudet C, Sanchez P, Patrac V, Denis P, Boirie Y, Walrand S, Gueugneau M. “Characterization of the Skeletal Muscle Proteome in Undernourished Old Rats.” International Journal of Molecular Sciences 2022;23(9). PubMed.
• [8] Koshihara M, Masuyama R, Uehara M, Suzuki K. “Effect of dietary calcium:phosphorus ratio on bone mineralization and intestinal calcium absorption in ovariectomized rats.” BioFactors 2004;22(1-4):39-42. PubMed.
• [9] Merck Veterinary Manual. “Fibrous Osteodystrophy in Animals (nutritional secondary hyperparathyroidism).” link.
• [10] Gründemann D et al. “Discovery of the ergothioneine transporter.” Proc Natl Acad Sci U S A 2005;102(14):5256-61. PubMed.
• [11] Beelman RB et al. “Is ergothioneine a longevity vitamin limited in the American diet?.” Journal of Nutritional Science 2020;9:e52. PubMed.
• [12] Zhao X, Jia J, Lin Y. “Taurine Content in Chinese Food and Daily Taurine Intake of Chinese Men.” Advances in Experimental Medicine and Biology 1998;442:501-505. PubMed.
• [13] Zeisel SH, Mar MH, Howe JC, Holden JM. “Concentrations of choline-containing compounds and betaine in common foods.” Journal of Nutrition 2003;133(5):1302-1307. PubMed.
• [14] Calder PC. “Omega-3 polyunsaturated fatty acids and inflammatory processes: nutrition or pharmacology?.” British Journal of Clinical Pharmacology 2013;75(3):645-662. PubMed.
• [15] Sen CK et al. “Tocotrienols: Vitamin E beyond tocopherols.” Life Sciences 2006;78(18):2088-2098. PubMed.
• [16] Yao G, Cao C, Zhang M, Kwok LY, Zhang H, Zhang W. “Lactobacillus casei Zhang exerts probiotic effects to antibiotic-treated rats.” Computational and Structural Biotechnology Journal 2021;19:5888-5897. PubMed.
• [17] Xue S, Liu Q, Feng J, Feng Y, Jia H, Yi L, Zhao S, Zhu J. “Applications and Action Mechanisms of Yucca schidigera Extract in Livestock, Poultry and Aquatic Animals.” Animals (Basel) 2026;16(15):2376. PubMed.
• [18] Oiso N et al. “The rat Ruby (R) locus is Rab38: identical mutations in Fawn-hooded and Tester-Moriyama rats derived from an ancestral Long Evans rat sub-strain.” Mammalian Genome 2004;15(4):307-314. PubMed.
• [19] Ninkovic I et al. “The role of Rab38 in platelet dense granule defects.” Journal of Thrombosis and Haemostasis 2008;6(12):2143-2151. PubMed.
• [20] Schaafsma A, Pakan I, Hofstede GJ, Muskiet FA, Van Der Veer E, De Vries PJ. “Mineral, amino acid, and hormonal composition of chicken eggshell powder and the evaluation of its use in human nutrition.” Poultry science 2000;79(12):1833-8. PubMed.
• [21] Roldán M, Mesias M, Morales FJ. “Balancing nutrition and safety: Acrylamide and HMF in biscuits from different cereal flours.” Food chemistry: X 2026;34:103579. PubMed.
• [22] U.S. Department of Agriculture, Agricultural Research Service. “FoodData Central (SR Legacy food composition records and household portion weights).” USDA FoodData Central 2019. link.
• [23] Roof Rat (this site): “Rat Food and Menu Builder (the site’s own food library and calcium arithmetic).” link.
• [24] Kim KP, Shin KO, Park K, Cho Y. “Borage Oil Enhances Lamellar Body Content and Alters Fatty Acid Composition of Epidermal Ceramides in Essential Fatty Acid-Deficient Guinea Pigs.” Lipids 2021;56(3):345-353. PubMed.
• [25] Oba PM, Hwisa N, Huang X, Cadwallader KR, Swanson KS. “Nutrient and Maillard reaction product concentrations of commercially available pet foods and treats.” Journal of Animal Science 2022;100(11). PubMed.
• [26] Zafalon RVA, Risolia LW, Vendramini THA, Ayres Rodrigues RB, Pedrinelli V, Teixeira FA, Rentas MF, Perini MP, Alvarenga IC, Brunetto MA. “Nutritional inadequacies in commercial vegan foods for dogs and cats.” PLoS One 2020;15(1):e0227046. PubMed.
• [27] Czerwonka M, Bialek A. “Fatty Acid Composition of Pseudocereals and Seeds Used as Functional Food Ingredients.” Life 2023;13(1):217. PubMed.
• [28] Moravcova M, Siatka T, Krcmova LK, Matousova K, Mladenka P. “Biological properties of vitamin B12.” Nutrition Research Reviews 2025;38(1):338-370. PubMed.
• [29] Lind T, Lind PM, Hu L, Melhus H. “Studies of indirect and direct effects of hypervitaminosis A on rat bone by comparing free access to food and pair-feeding.” Upsala journal of medical sciences 2018;123(2):82-85. PubMed.
• [30] Mortensen JT, Brinck P, Binderup L. “Toxicity of vitamin D analogues in rats fed diets with standard or low calcium contents.” Pharmacology & Toxicology 1993;72:124-127. PubMed.
• [31] Laporta J, Peters TL, Weaver SR, Merriman KE, Hernandez LL. “Feeding 5-hydroxy-l-tryptophan during the transition from pregnancy to lactation increases calcium mobilization from bone in rats.” Domestic Animal Endocrinology 2013;44(4):176-184. PubMed.
• [32] Calvo MS, Babu US, Garthoff LH, Woods TO, Dreher M, Hill G, Nagaraja S. “Vitamin D2 from light-exposed edible mushrooms is safe, bioavailable and effectively supports bone growth in rats.” Osteoporosis International 2013;24:197-207. PubMed.
• [33] Mavric E, Wittmann S, Barth G, Henle T. “Identification and quantification of methylglyoxal as the dominant antibacterial constituent of Manuka (Leptospermum scoparium) honeys from New Zealand.” Molecular Nutrition & Food Research 2008;52(4):483-489. PubMed.
• [34] Gill R, Poojar B, Bairy LK, Praveen KSE. “Comparative Evaluation of Wound Healing Potential of Manuka and Acacia Honey in Diabetic and Nondiabetic Rats.” Journal of Pharmacy & Bioallied Sciences 2019;11(2):116-126. PubMed.
• [35] Katsube M et al. “Ergothioneine promotes longevity and healthy aging in male mice.” GeroScience 2024;46:3889-3909. PubMed.
• [36] Burr GO, Burr MM. “A new deficiency disease produced by the rigid exclusion of fat from the diet.” Journal of Biological Chemistry 1929;82:345-367. DOI.
• [37] Hirasawa T, Omi N, Ezawa I. “Effect of 1alpha-hydroxyvitamin D3 and egg-shell calcium on bone metabolism in ovariectomized osteoporotic model rats.” Journal of bone and mineral metabolism 2001;19(2):84-8. PubMed.
• [38] Brun LR, Lupo M, Delorenzi DA, Di Loreto VE, Rigalli A. “Chicken eggshell as suitable calcium source at home.” International Journal of Food Sciences and Nutrition 2013;64(6):740-743. PubMed.