Commercial Diets

Lab Blocks / Kibble

Nora EatingThere are three main brands of lab blocks that are considered to be high quality food for pet rats. The companies who manufacturer these diets are Harlan Teklad (Since June 2015, Harlan Teklad has merged with Huntingdon Life Sciences and three subsidiaries under the company name, Envigo),  Oxbow Animal Health and Mazuri.

I would not recommend feeding any of the rodent blocks or seed mixes typically sold in pet stores. Manufacturers of rodent diets sold in pet stores do not come close having done comprehensive research into the nutritional needs of rats. The ONLY exception to this are the Oxbow diets which are found in some pet stores (details below).

Wendell EatingBefore giving an overview of the three major brands of commercial rat diets, I’d like to talk a little about soy and protein.


From the research I’ve done, I believe it is helpful to feed soy, especially to females. Soy has been shown to reduce the occurrences of mammary tumors. After upper respiratory infections, mammary tumors are the second most prevalent health concern for pet rats.

Please Note: There are plenty of people who believe the opposite, that soy actually causes mammary tumors.


There are varying opinions on how much protein should be in a rat’s diet. Many experts believe the need for protein decreases as a rat ages. The ranges recommended throughout a rat’s lifespan are from 23-24% for babies and young rats down to as low as 5% for geriatric rats. I have not, however, seen any commercially available diets that have only 5% protein.


Harlan Teklad

Harlan Teklad lab blocks are designed specifically for lab rats and are one of the highest quality foods you can buy.  Even though they look like particle board, Harlan Teklad lab blocks are a nutritionally complete food. They contain all the essential vitamins, minerals, amino acids, fatty acids and macronutrients your rat needs.

However, I have to say I cringe when thinking that these diets were originally and are primarily designed for laboratory rats. (Hence the name “lab blocks”.) I am not a supporter of using any animals for laboratory testing. Unfortunately, this diet is still held in high esteem by many experienced pet rat owners even though the manufacturer created this diet for laboratory rats who suffer and even die during and after being subjected to experimental tests. Not only does Envigo manufacture and sell laboratory animal diets, but they also breed and sell the animals used for scientific experiments. The lab animals they sell range from multiple types and strains of rats to mice, guinea pigs, rabbits and dogs.

As mentioned above, in June of 2015 Harlan Laboratories merged with Huntingdon Life Sciences to form the company, Envigo. Huntingdon Life Sciences is one of the world’s largest animal testing labs. In good conscience, I’ve stopped feeding this diet to my own rats. I am still including the information on Harlan Teklad lab blocks here, however, since many pet rat owners still believe it to be one of the best diets.

Out of the many rodent diets they make, there are three Teklad lab block formulas most widely used for pet rats.

Even thought they look like particle board, Harlan Teklad lab blocks are nutritionally balanced and complete

Even thought they look like particle board, Harlan Teklad lab blocks are nutritionally balanced and complete

  • Teklad 2018 – for pregnant, nursing or growing rats up to 8 months
  • Teklad 2014 – maintenance formula for the average size adult rat, also good for overweight and/or older rats

The above two Teklad lab block formulas contain no fish meal, meat meals or meat by-products, no alfalfa meal and reduced or eliminated soybean meal. (Soybean meal is only included in the ingredients of Teklad 2018.) The last two digits of each of the Teklad diets above corresponds to the percentage of protein in each diet. Teklad believes low fat, low protein diets promote longevity and normal body weight in rodents. The Harlan Teklad lab blocks specified above have only 4-6% fat.

Another diet, Teklad 8604, has soybean meal listed as the first ingredient and has a protein content of 24.3%. Teklad 8604 is designed to support gestation, lactation, and growth of rodents. This diet is a good one for young unspayed female rats since soybean meal is listed as the first ingredient.


Oxbow Essentials Regal Rat

Oxbow Essentials Regal Rat

Oxbow Essentials

Oxbow Animal Health offers two rat diets. One is for adults and the other is for young, pregnant or nursing rats.

For adults, Oxbow’s Essentials – Adult Rat Food, is a small kibble with 15% crude protein. This diet was introduced and recommended to me by my rats’ veterinarian. Oxbow’s adult, Regal Rat, diet is nutritionally complete and is low-fat to help maintain an ideal weight. The first five ingredients are Whole Brown Rice, Oat Groats, Wheat Bran, Wheat, and Soybean Meal.

For young rats, Oxbow Essentials Mouse & Young Rat Food contains 18% protein. Besides being used as a rat food,this diet can be fed to mice of all ages. Oxbow’s young rat diet contains added vitamins and minerals and is nutritionally complete. This diet’s first ingredient listed is corn, however, so it’s not ideal. The  first five ingredients listed are Ground Corn, Soybean Meal, Wheat Middlings, Soybean Hulls, and Dried Whey. It contains no artificial preservatives, colors or flavors. It’s in the shape of a lab block. (I don’t know why they decided to make the young rat food a big block and the adult food a small kibble!)

I’ve been able to find the Oxbow diets in some, but not all, pet stores. Online, both the adult and young rat diets (Oxbow Essentials Adult Rat and Oxbow Essentials Mouse & Young Rat) can be found at the lowest prices on



Wendell Eating Mazuri’s Rat & Mouse Diet is their only pet rat formulation. They promote it as meeting the nutritional requirements for “breeding and non-breeding rodents”.  It comes in the form of a lab block and, at 23%, this diet is very high in protein. Dehulled Soybean Meal is the first ingredient which makes it ideal for female rats if you believe that soy helps prevent mammary tumors (which I do). The Mazuri Rat & Mouse diet is a vegetable-based formulation. Because of the high level of protein, I would only feed this diet to young rats since many experts advocate feeding decreasing levels of protein as a rat ages.

The Mazuri Rat & Mouse Diet can be found for the lowest price on

Mazuri also makes diets for Zebra, Moose, Polar Bear and even Reindeer.


Last  updated 7/30/17

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18 Responses so far.

  1. Lucy Kaul-Hurst says:

    How do the Purina companies Lab Blocks rate?

    My rats have liked them, and I’ve heard the hard blocks help keep their teeth worn down. I buy fresh batches from a local feed store that sells a large amount.

    PS- I’ve had problems with stale food mixes and open bin Lab Blocks in several pet stores, even if the package date says they are within the sell date. Some have actually smelled rancid. The added vitamins and antioxidants arent much good then!

    • Hi Lucy,

      I totally agree it’s not a good idea to buy lab blocks from bins.

      My current favorite diet for adult rats is the Oxbow Essentials Regal Rat food. Compared to other diets, the first five ingredients in the Oxbow adult diet are much healthier. Both Harlan Teklad and Purina make formulas for rats used in laboratory experiments. I really like the fact that Oxbow does not make diets for laboratory rats.

      The Oxbow Essentials Regal Rat diet is available online. The lowest price right now is $9.34 for a 2.5 lb bag from

      Listed below are the protein levels and the first five ingredients of several rat diets including Purina. The ideal level of protein for adult rats is 14-15%. You’ll see that the Oxbow diet has an appropriate level of protein and that the first five ingredients are much healthier than what’s found in the other diets. You’ll also see that the Purina rat diets contain too much protein.

      There are two Purina rat blocks I’ve heard of people feeding their rats:

      Purina Laboratory Rodent Diet 5001
      Protein = 25%
      First five ingredients = Dehulled soybean meal, ground corn, dried beet pulp, fish meal, ground oats

      Purina Rat Diet 5012
      Protein = 25%
      First five ingredients = Ground corn, dehulled soybean meal, fish meal, wheat middlings, cane molasses

      Harlan Teklad 2014 [Harlan Teklad is also sold under the company name of Envigo or as Native Earth]
      Protein = 14%
      First five ingredients = Wheat middlings, ground wheat, ground corn, corn gluten meal, calcium carbonate

      Oxbow Essentials Regal Rat
      Protein = 15%
      First five ingredients = Whole brown rice, oat groats, wheat bran, Wheat, Soybean Meal

      Thanks for asking your excellent question!

      Best Wishes to You & Your Rats,

      Jasmine | About Pet Rats

  2. Em Dockins says:

    Hello, I have been reading over a lot of the info and noticed you mentioned lower protein diets. I recently got a harley rat and was not prepared for them to need a special diet. I recently learned they are protein sensitive and need a low protein diet. I have not been able to find such diets online and was wondering if you knew or could point me in the direction so I can properly care for my guy.

    • Hi There,

      As you may already know, Harley rats were first bred in 2002. At that time they did frequently develop skin issues due to protein sensitivity. However, as breeding practices have progressed, I don’t believe the protein levels of their diets is as big an issue as it used to be

      Has your rat shown symptoms of protein sensitivity?

      If you’re not seeing any signs that your rat is sensitive to protein, I would think that the Harlan Teklad 2014 would be a great diet for your guy if you do want to keep him on the low-protein side. (The Oxbow Adult diet—which is one of my favorites—has 15% protein and the Harlan Teklad 2014 has 14% protein.) 14% is as low as commercial diets go, as far as I know.

      One of my current rats looks as if he’s a Harley and he and his friend are on the 14% protein diet.

      If your rat is showing any symptoms, I’d first have him examined by a veterinarian (who’s knowledgeable about pet rats) to rule out external parasites or any other cause of the symptoms. If your vet believes he should be on a lower than 14% protein diet, you can always supplement the commercial diet with a larger quantity of vegetables and grains.

      I hope this addresses your question and gives you some ideas on how best to care for your Harley. You sound like a fantastic rat parent!

      Best Wishes to You & Your Rats,

      Jasmine | About Pet Rats

    • Laurence says:

      Another brand not listed here that I wouldn’t super recommend due to the low protein is Selective for rats. My vet recommended this to me because she got her facts wrong so now I have a bag of it kind of just sitting here. It has 12% protein and the first ingredients are Whole Wheat, Soybean Meal, whole barley, whole oats, dried apples. It comes in an oxbow shaped kibble and it’s hard food.

    • Hi Laurence,

      Thanks for providing the information about the Supreme Selective Fortified Diet for Rats. I’ve heard that lower protein diets are especially good for older male rats. Debbie Ducommun from The Rat Fan Club mentions 14% protein as being good for older males. I agree, though, that 12% is definitely too low for young rats.

      I am a big fan of the Oxbow Essentials Adult Rat Diet which seems to have optimum levels of the proper vitamins and minerals as well as a 15% protein level.

      I’d like to do some further research into pet rat nutrition. I wish there was an organic, freshly blended diet available, that had all of the nutritional ingredients pet rats need.

      Thank you again, Laurence for bringing up this diet as well as your opinion on it. I’m curious to know what diet you’ve decided to feed your rats.

      Best Wishes to You & Your Rats,

      Jasmine | About Pet Rats

  3. Victoria says:

    All this information is wonderful but as someone who is going to be a first time mother to 2, 6 week female rats I’m still a little confused and would like a little bit of guidance! I just want to give them the right food. Maybe a few tips what to give them on he side too?
    Thank you so much!

    • Hi Victoria!

      Congratulations on preparing to become a first-time mother to your new baby rats! I’m so glad to hear you’re interested in learning more about proper pet rat nutrition.

      A good diet for babies is either the Oxbow Essentials – Mouse & Young Rat Food or the Harlan Teklad 8604. Both are high in soy with the Harlan Tekald listing soy as the first ingredient.

      Recommendations for foods to give them on the side can be found on My Daily Menu for Pet Rats which includes all the foods I give my own rats on a daily basis.

      I definitely recommend Green Mush which is listed on my Daily Menu page.

      Since you’re getting girls, it’s important to feed them foods high in soy such as soybeans and tofu to help prevent mammary tumors. I also highly recommend getting them spayed (which both helps prevent mammary tumors AND promotes longevity) as long as you have a veterinarian in your area who’s both comfortable and very experienced with doing pet rat spays.

      I hope this information is helpful for you. Don’t hesitate to let me know if you have any other questions about pet rats.

      Again, CongRATS!

      Best Wishes to You & Your New Babies,

      Jasmine | About Pet Rats

      PS – You can receive a free copy of my Guide to Essential Pet Rat Supplies by signing up for About Pet Rats updates. The Guide shows where you can order both diets mentioned above as well as all of the other essentials for your new rats.

  4. Gail says:

    I just got a baby hairless male rat.What is the est food to feed?I see the oxbow for young rats is not good I have fed in the past harlan blocks to my females but not sure on the hairless he does need more protein but his brother is all hair so a little confused.HELP

    • It is a good idea to feed a little more protein and calories to compensate for hairless rats’ faster metabolisms. If your hairless baby boy is 10 months or younger, I’d feed him the Harlan Teklad 8604 diet. It contains 24.3% protein. This is also a great diet for females 8 months or younger, especially if they’re unsprayed since the first ingredient is soybean meal. A second option would be the Mazuri diet since it has 23% protein.

      If all of your rats are around 10 months or younger Harlan Teklad 8604 would work great as their main staple. When mixed age groups are housed together, it’s difficult to be able to provide the “perfect” nutrition for all age groups at once. If you do have a combination of baby/young/adult/senior rats, feed some of each type of block or kibble appropriate for the ages you have.

      Besides the information found on this page, you can get my free guide to Essential Supplies for Your Pet Rats which includes specific diets for each age.

  5. Krystal says:

    I love how you broke down the diet here, as well as the composition of the food. Personally, I love Oxbow. But it is far from the main food supply for my rats. I tend to offer mine a wide variety of foods (as I’m sure most people do), mostly because they are scavenger animals who find random foods at different times in the wild. While they are domesticated, I can only assume (and they only prove LOL) they kept their wide range of food preferences even after domestication 🙂 My babies feast!!!

    • Hi Krystal,

      Great point! Variety is extremely important.

      I love the adult Oxbow diet, too. I’m currently feeding my rats both the adult Oxbow and the 2014 Harlan Teklad for even more variety. 🙂

      Hope you and your rats are doing great!

      Jasmine | About Pet Rats

  6. Hello, I am planning to adopt 6 week old baby rats from a breeder. The breeder I am getting them from feeds her rats Mazuri, although I believe Oxbow Regal Rat is a better choice. Although, when I adopt them I will be giving them Oxbow Essentials Young rat and mouse. How do I introduce the Oxbow Essentials young rat and mouse if the babies were eating Mazuri? And is Oxbow Essentials Young rat and mouse diet a good choice? Some people, do not recommend this diet because it is smelly and makes their rats have an unhealthy odor to them as well as containing alfalfa they cannot digest and ground corn as one of the main ingredients. Any suggestions? Helpful tips would be highly appreciated.

    • Hi Brooke,

      A lot of breeders do use Mazuri. It’s not a bad diet for babies since it has 23% protein. It’s especially good for female babies since the first ingredient is soybeans. However, the second ingredient is corn which, as you’re aware, is not ideal. Dried corn can contain high levels of nitrates and amines as well as harmful fungi. Nitrates and amines can combine in the stomach to form nitrosamines which may cause cancer.

      I would choose Harlan Teklad 8604 for your new babies. It contains 24.3% protein and the first two ingredients are soybean and wheat. The third ingredient is corn. (It’s difficult to find a young rat formula without corn.) One reason I’d choose Harlan Teklad 8604 over the Oxbow Young Rat formula is because the Oxbow Young Rat diet lists corn as the first ingredient. Also, the Oxbow Young Rat diet only contains 18% protein which, for growing rats, is more beneficial at the higher percentages found in the Harlan Teklad 8604 and Mazuri diets. If you don’t want to buy the Harlan Teklad 8604, then I’d say the second best diet for babies would be the Mazuri diet since the protein level is higher than the Oxbow Young Rat diet and corn is at least the second (rather than first) highest ingredient.

      If you do decide to switch your new babies’ diets from Mazuri to Harlan Teklad 8604, ask the breeder if s/he will give or sell you a cup of the Mazuri lab blocks so you can make the change gradually. Start out with giving the new diet as 25% of the total amount of lab blocks eaten per day. Every few days increase the new diet up to 50%, then 75% and finally 100%.

      You can purchase Harlan Teklad 8604 from The Rat Shop or
      The Crafty Rat.

      Vera eating a salad

      Be sure to give fresh fruits and vegetables as well as the lab blocks. I also highly recommend Green Mush. After I began feeding my rats Green Mush I found they lived up to a year longer than without Green Mush.

      Once they become adults, gradually transition them to an adult diet. Males stop growing at around 8-10 months and females stop growing at around 6-8 months. For adult food I like the Oxbow Essentials Regal Rat Adult Diet which is 15% protein. The first five ingredients are whole brown rice, oat groats, wheat bran, wheat and soybean meal. There is no corn or alfalfa in this diet!

      If you are getting female rats, I highly recommend spaying them—as long as you can find a veterinarian who has lots of experience in spaying rats. I’m sure you’ll agree it’s better to have a rat veterinarian who is both confident and competent. I bring this up here because spaying significantly reduces the occurrence of mammary tumors. Diet also contributes to decreasing chances of females developing mammary tumors. Organic soy products (such as tofu and soybeans) along with miso are food items you can add to female rats diets if they are not (yet) spayed.

      I’m excited you’ll soon have your new babies! Let me know if you have more questions at any time.

      Best Wishes,

      Jasmine | About Pet Rats

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  7. abrune892 says:

    I’ve read soy is bad for rats, and in the wild rats stay away from soy plants…. Also most soy you’d find in the US is genetically modified which is never good for any living creature….. I also read that corn is bad for rats because of the mold issue… I’m getting so confused at what to feed my rats now….

    • There are some people who believe soy is not good for rats. From research studies I’ve read, however, soy can help prevent mammary tumors. You can also read what Debbie Ducommon wrote on her Rat Fan Club site about soy as being a helpful part of a cancer prevention diet (Scroll to bottom of page.)

      I live in the US and always buy organic tofu which is non-genetically modified. Wildwood, which is “non-GMO project verified” is my favorite brand of tofu. I agree that it’s not a good idea to buy or feed genetically modified food to anyone.

      Regarding corn, it is bad for rats if it is moldy. If you buy fresh, organic corn it is not likely to be moldy. Mold on corn is most frequently found when you buy nut and seed mixes that are sold in pet stores as a rat diet. These mixes often contain dried corn which can contain mold, among other unhealthy ingredients.

      Thanks for bringing up these excellent points. It’s great to see that you’re studying and learning about what foods are best for your rats!

  8. Paul Littlefield says:

    Just so you know, Mazuri does make a formula for adult rats, called Mazuri Rodent Breeder 6F. It’s confusing, because you’d expect this formula would be the high-protein one, but it’s the standard 16% for adults.

    • Hi Paul,

      Thanks for mentioning the Mazuri Rodent Breeder 6F. I didn’t include it on this page since it’s made specifically for “breeding colonies”. However, you never know, it could be helpful for someone out there to know about this formula.

      I read on Mazuri’s website that their Rodent Breeder formula contains yucca shidigera extract which “reduces aerosol ammonia in animal facilities”. Sad to think about breeder rats in animal facilities.

      That is interesting that their breeding formula contains 16% protein while their basic pet rat formula (for all ages) contains 23% protein. I’m thankful there are commercial diets available with lower protein such as Oxbow (15% crude protein) and Harlan Teklad (14% crude protein).

      Thanks again for writing about Mazuri’s other rodent diet!

      Jasmine | About Pet Rats