Manganese in a raw diet
Let’s keep exploring the micronutrients our cats need and how to supplement them (if needed). In this article, we are going to talk about manganese: what it is, why it’s important, and its sources, like the blue mussel or green tripe.
What is manganese?
Manganese, like iodine, is a mineral (an inorganic element) and—more precisely—a micromineral or trace element: it’s present in the body in very small amounts. To give you an idea of how small these amounts are, the body of a 4 kg cat (8.8 lbs) contains around 2.3 mg of manganese.
Even if manganese is present in very small quantities in the diet and in the body, it has some important roles.
Manganese participates in bone and cartilage development as well as for the metabolism of lipids and proteins. [1][2][3]
Manganese deficiency hasn’t been reported in cats. However, this doesn’t mean that cats can’t be deficient in manganese. What it means is that there hasn't been any study in which cats were purposely fed a diet deficient in manganese, nor a case report of manganese deficiency. In fact, reporting a case of nutrient deficiency is difficult as the symptoms can often be confused with more common diseases. A deficiency can take from a few months to several years to appear and it requires knowing precisely the diet of the cat during this time.
Fortunately, we know what the symptoms of manganese deficiencies are in other species: bone and joint abnormalities as well as reproduction issues. In newborn and growing animals, a manganese deficiency can cause retarded growth, bowing, and shortening of the forelegs. In adults, it may lead to lameness and joint enlargement; there are also reproductive issues that have often been observed, such as increased abortion rates as well as stillbirth and low birth rates. [1][2][3]
As manganese is the least toxic trace mineral, manganese excess is a relatively low cause of concern. Nonetheless, at least one case of manganese toxicity has been reported in a dog that ate an excessive amount of joint supplement tablets that contained manganese. The dog ingested 538 times its daily manganese requirement, which led to hepatic failure and euthanasia. [5]
How much manganese does your cat need?
Let’s look at how much manganese our cats need:
The NRC recommendation is 1.2 mg/1000 kcal of diet, equivalent to 4.8 mg per kg of DM with 4000 kcal/kg.
It means that an average 4kg cat will need 0.3 mg of manganese a day.
This recommendation is based on a study made on a purified diet with safety margins added for lower bioavailability in standard diets. [2]
The safe upper limit legally defined by the European regulations is 42.5 mg/1000 kcal equivalent to 170 mg per kg of DM.
Where do you find manganese?
Manganese is found in many ingredients such as spices (ginger, cinnamon, cloves), mussels, leafy vegetables, rice…
However, manganese content is quite low in muscle meat: it’s generally around 0.08 mg/1000 kcal, so well below the requirement. Organs such as liver (~2 mg/1000 kcal) and kidney (~1.3 mg/1000 kcal) and bones have higher manganese content. Green tripe is another notable animal product which is particularly rich in manganese, at 15 mg/1000 kcal.
As muscle meat is low in manganese, raw diets based on Prey Model or BARF ratios will almost always be deficient in manganese.
In the raw feeding community, it’s common to say that fur, feathers, and wool of prey are rich in manganese. However, it seems that this manganese content depends on the diet of the animal, which means it’s not always rich in manganese. Additionally, given the low digestibility of feathers and fur, it’s not sure their manganese content would be bioavailable. I would advise against relying on feathers and fur to fulfill the manganese requirement of cats. [4]
How to supplement a diet with manganese?
The best way to add manganese to a diet is often to use mussels: they are so manganese-rich that only a small amount is sufficient. They are also lean and provide omega-3 fatty acids. Be sure to feed blue or black mussels and not green-lipped mussels which have lower amounts of manganese.
It’s recommended to feed cooked mussels: you can often find them already steamed, frozen, and without shells making them extremely easy to feed. You will find a calculator at the end of this article to determine how much your cat may need.
An alternative to mussels is green tripe (if you can find it and if your cat likes its taste): it’s also very rich in manganese.
While leafy greens, rice, and legumes contain manganese, the quantity of the ingredient needed is often too high to provide enough manganese. It’s also likely that the bioavailability of manganese in plant food is lower than in animal food. So, while you can use these ingredients, I wouldn’t rely exclusively on them. [4][7]
Similarly, using spices such as ginger or cinnamon isn’t suitable as the bioavailability of these ingredients is questionable and most cats won’t like the taste.
If you can’t find either mussels or green tripe, your best option would be to use a manganese supplement. I would recommend using a chelated manganese supplement like the one of Solgar as they have better bioavailability. As these supplements are made for humans, they are quite concentrated and you will often need 1 or fewer capsules for a month.
From my personal experience, you can consider that the meat, organs, and raw meaty bones will fulfill around 30% of the manganese requirement of your cat. You will then need to supplement the other 70%.
Manganese in prey/nature
Once again, when you look at the nutritional data of domestic whole prey, the quantity of manganese exceeds the recommendation for adult prey. Even juvenile prey, while being below the recommended amount of manganese is still higher than meat. We know that the nutritional content of domestic prey and of wild prey is different but it’s likely that the diet of wild cats contains enough manganese according to the nutritional recommendation. [6][7]
To recap, manganese is a micronutrient often lacking in a homemade diet and—like vitamin E—this nutrient is present in higher quantities in prey compared to commercial meat. I recommend adding mussels, green tripe, or a manganese supplement to the diet of your cat as manganese is important for joint health.
Supplement calculator
This calculator is made using the metabolic weight formula: the recommended allowance is 0.119mg per kg/BW^0.67 equivalent to 1.2mg per 1000kcal.
The cooked blue mussel value is 6.8mg/100g (USDA).
Manganese in raw meat, organs, whole preys and foodstuff
| mg of manganese / 100g as fed | mg of manganese / 1000kcal | |
|---|---|---|
| Cut | ||
| Chicken breast | 0.01 | 0.08 |
| Chicken breast with skin | 0.02 | 0.12 |
| Beef chuck stew meat | 0.01 | 0.08 |
| Ground beef 10% | 0.01 | 0.06 |
| Ground beef 20% | 0.01 | 0.04 |
| Beef brisket point | 0.01 | 0.04 |
| Lamb shoulder chop | 0.02 | 0.08 |
| Pork leg shank | 0.02 | 0.10 |
| Turkey thigh with skin | 0.01 | 0.06 |
| Veal shoulder | 0.03 | 0.24 |
| Venison | 0.04 | 0.33 |
| Organs | ||
| Beef liver | 0.31 | 2.30 |
| Chicken liver | 0.26 | 2.18 |
| Beef kidney | 0.14 | 1.41 |
| Lamb kidney | 0.12 | 1.24 |
| Chicken heart | 0.09 | 0.59 |
| Turkey heart | 0.10 | 0.71 |
| Beef spleen | 0.07 | 0.67 |
| Whole Prey | ||
| Mouse, neonatal <3g | 0.00 | 0.04 |
| Mouse, juvenil 3-10g | 0.24 | 1.97 |
| Mouse, adult > 10g | 0.25 | 1.47 |
| Guinea pig, 10 week | 0.21 | 0.94 |
| Rat, neonatal < 10g | 0.13 | 1.17 |
| Rat, adult < 50g | 0.37 | 1.73 |
| Quail, japanese | 0.22 | 0.94 |
| Rabbit stillborn | 0.06 | 0.51 |
| Rabbit 30 to 45d | 0.92 | 6.49 |
| Rabbit <65d skinned | 0.24 | 1.43 |
| Foodstuff rich in manganese for reference | ||
| Ginger, powder | 33.30 | 99.40 |
| Wheat germ | 17.00 | 45.33 |
| Blue mussel, cooked | 6.80 | 39.53 |
| Green tripe | 2.57 | 15.30 |
| Spirulina | 1.90 | 6.55 |
| Spinach, boiled | 0.90 | 39.00 |
| Kale, boiled | 0.54 | 15.00 |
| Lentils, boiled | 0.44 | 3.46 |
| White rice, cooked | 0.35 | 2.85 |
Sources
[1] Linda P. Case et al. 2015. Canine and Feline Nutrition.
[2] National Research Council. 2006. Nutrient Requirements of Dogs and Cats. Washington, DC: The National Academies Press.
[3] Thatcher, Craig & Hand, M.S. & Remillard, Rebecca. (2010). Small animal clinical nutrition.
[4] Trace Elements in Human and Animal Nutrition, volume 1, 5th edition, 1986, Walter Mertz.
[5] Borchers, A., Epstein, S. E., Gindiciosi, B., Cartoceti, A., & Puschner, B. (2014). Acute enteral manganese intoxication with hepatic failure due to ingestion of a joint supplement overdose. Journal of veterinary diagnostic investigation : official publication of the American Association of Veterinary Laboratory Diagnosticians, Inc, 26(5), 658–663.
[6] Kerr, K. R., Kappen, K. L., Garner, L. M., & Swanson, K. S. (2014). Commercially available avian and mammalian whole prey diet items targeted for consumption by managed exotic and domestic pet felines: macronutrient, mineral, and long-chain fatty acid composition. Zoo biology, 33(4), 327–335.
[7] Dierenfeld, Ellen & Alcorn, Heather & Jacobsen, Krista. (2002). Nutrient Composition of Whole Vertebrate Prey (Excluding Fish) Fed in Zoos. 7994.
Sources for the table
USDA
CIQUAL
Kerr, K. R., Kappen, K. L., Garner, L. M., & Swanson, K. S. (2014). Commercially available avian and mammalian whole prey diet items targeted for consumption by managed exotic and domestic pet felines: macronutrient, mineral, and long-chain fatty acid composition. Zoo biology, 33(4), 327–335.
Dierenfeld, Ellen & Alcorn, Heather & Jacobsen, Krista. (2002). Nutrient Composition of Whole Vertebrate Prey (Excluding Fish) Fed in Zoos. 7994.