Zinc in a raw diet
Zinc is one of the minerals often said to be lacking in a raw diet. Today, I’m going to go into more detail about this, and see when you need to supplement it. I will explain what zinc is and its roles, how much zinc your cat needs, in which foods you can find it, and more!
What is zinc and what are its roles?
Like iron, manganese, and iodine, zinc is a micromineral or trace element. This means that it’s an inorganic element present in very small quantities in the body.
However, even if it’s present in small quantities, it doesn’t mean that zinc doesn’t have an important role in the body. Zinc plays a role in the metabolism of lipids, proteins, and carbohydrates and it’s necessary for the synthesis of DNA, RNA, and proteins. It’s also essential in order to have normal reproductive and immunity functions, as well as skin and wound healing.
A zinc deficiency causes anorexia, reproduction issues, immune system dysfunctions, and skin lesions. The first signs of zinc deficiency are often related to the skin and hair coat, such as a dull and coarse coat or even hair loss and depigmentation. In kittens, it’s also linked to growth retardation.
Contrary to other microminerals, zinc is relatively non-toxic. However, excess zinc will affect the absorption of other minerals and so it can cause a calcium, copper, or iron deficiency. [1][2][3][4][5]
How much zinc does your cat need?
As for iron, studies to determine the requirement of zinc were made on kittens. The current NRC recommendation for kittens is the following:
The minimum requirement of zinc is 12.5 mg per 1000 kcal, which is equivalent to 50 mg per kg of dry matter (DM) for a 4000 kcal/kg diet. This requirement is based on a study where a purified diet was fed.
The recommended amount of zinc is 18.5 mg per 1000 kcal, which is equivalent to 75 mg per kg of DM. This recommended amount was established with a 50% safety margin from the minimum requirement, to take into account a lower bioavailability in kibbles.
For adult cats, the recommended amount is the same, however, there isn’t a minimum requirement set, as it hasn’t been studied. When adult cats are fed a raw diet that has a high bioavailability, we could assume that the minimum requirement for kittens is also safe for adult cats. [2]
There is not enough research to define a safe upper limit, but up to 600 mg per kg DM has been fed safely to cats for several weeks (equivalent to 150 mg per 1000 kcal). However, the legal maximum defined by the EU for pet food is 227 mg per kg DM, equivalent to 56.7mg per 1000 kcal. [2][6]
Where can you find zinc?
Zinc is found mainly in meat, organs, seafood, and fish. Whole grains, nuts, and legumes also contain zinc in less amount, while fruits and vegetables don’t have much zinc.
The richest food in zinc by far is oysters, containing more than 200 mg of zinc per 1000 kcal. It’s also found in organs like liver, heart, and kidney, at around 20 to 40 mg of zinc per 1000 kcal. Red meat and especially lean beef is also particularly rich in zinc, and will often be the main contributor of zinc in a raw diet.
It’s important to pay attention to the amount of fat in a cut of meat, while lean beef at around 5% of fat contains 42 mg for 1000 kcal; ground beef with 20% fat contains only 16 mg for 1000 kcal.
In poultry, hard-working muscles which are darker in color are also richer in zinc. For example, chicken and turkey breasts contain respectively 5.7 mg and 10 mg per 1000 kcal while chicken and turkey thighs contain 13 mg and 25 mg per 1000 kcal.
Like for other minerals, the absorption of zinc can vary depending on many parameters. In particular, the bioavailability of zinc in plant food is reduced because of several anti-nutrients such as fiber and phytates. High levels of other minerals can also reduce absorption of zinc such as calcium, iron, and copper. [2]
Do you need to supplement zinc?
Contrary to some minerals like manganese and iodine which are always deficient in a PMR diet, depending on the meat you feed zinc supplements may not be needed. If you feed lean beef, zinc supplements generally won’t be needed. However, as white meat often contains less zinc than the minimum requirement and the recommended amount, a supplement will likely be needed.
Let’s look at some sample diets to get a better idea:
Example 1
If we consider a PMR recipe with a daily ration of 120 g, which is approximately 3% of Praline’s weight:
20 g chicken necks, 20 g beef hearts, 6 g beef liver, 6 g pork kidney, 12 g mackerel, and 56 g chicken breast.
The daily recommended amount of zinc for my cat Praline (3.7 kg) is 4.56 mg, the minimum requirement would be 3 mg.
This diet contains 1.78 mg of zinc which is only 39% of Praline’s recommended amount. If we consider the minimal requirement, the diet still covers only 59%. In that case, a zinc supplement would be needed.
Though, if we replace the chicken breast with turkey thigh, the diet contains 3.05 mg of zinc which is 66% of the recommended amount. The minimum requirement is entirely covered at 101% but if the diet has higher levels of copper and iron a supplement will be needed to avoid issues with reduced absorption.
Example 2
In this second example, let’s consider another PMR recipe but with red meat:
27 g chicken wings, 20 g chicken hearts, 6 g chicken liver, 6 g lamb kidney, 12 g sardine, and 49 g beef chuck stew meat.
The diet contains 5.16 mg of zinc which is 113% of Praline’s recommended amount and 173% of the minimum requirement. In that case, a supplement in zinc won’t be needed.
How to supplement zinc?
One way to provide zinc in a diet is to feed oysters as a few grams will generally provide enough zinc.
If you can find them fresh in your country, canned oysters are the best option, as it’s already cooked so you’ll avoid any bacteria and parasite contaminations.
However, if you can’t find oysters at all, a good alternative will be to feed a zinc supplement. The most common forms of zinc that you can find in supplements are chelated zinc like zinc bisglycinate, zinc picolinate, zinc citrate or zinc gluconate, or inorganic zinc like zinc sulfate or zinc oxide. Chelated zinc has better absorption than inorganic zinc, so I would recommend using a chelated zinc form. As always with supplements, you need to be careful about the dosage you are giving, especially because extra zinc will reduce the absorption of copper, another essential micronutrient.
If you want to accurately supplement zinc, the best way would be to use a spreadsheet (like the one from Raw Fed and Nerdy) or a software to calculate the requirement of zinc and how much is already provided in the diet. To give you a rough estimation, you will find a calculator at the end of this article.
Because the body has a limited ability to store zinc, it’s better to provide it daily and not rely on balance over a long amount of time. [7]
What about zinc in nature?
If we look at the amount of zinc in whole prey, most of the prey contains an amount of zinc above the minimum requirement but below the recommended amount. So it’s unlikely that wild cats would be deficient in zinc as their diet provides enough zinc to fulfill the minimum requirement. [8][9]
This could also mean that the recommended amount has a safety margin which isn’t necessarily needed in a raw meat-based diet. However, there isn’t enough research on the zinc requirement to confirm that hypothesis. But this highlights that a raw diet below the minimum requirement in zinc definitely should be supplemented.
Zinc is an important trace mineral as–among others–a zinc deficiency could cause skin and fur issues. Zinc can be lacking in a raw diet, especially if there isn’t any lean beef. In that case, zinc will need to be supplemented with either oysters or a zinc supplement.
Supplement calculator
Supplement
Oyster
This calculator is made using the metabolic weight formula:
The recommended allowance is 1.90 mg per kg/BW^0.67 equivalent to 18.5 mg per 1000kcal.
The minimum requirement is 1.25 mg per kg/BW^0.67 equivalent to 12.5 mg per 1000kcal
The cooked Pacific oysters value is 33.2mg/100g (USDA).
Zinc in raw meat, organs, whole preys
| zinc mg / 100g as fed | zinc mg per 1000kcal | |
|---|---|---|
| Cut | ||
| Chicken breast | 0.68 | 5.7 |
| Chicken breast with skin | 0.80 | 4.7 |
| Chicken thigh | 1.58 | 13.1 |
| Beef chuck stew meat | 5.43 | 42.4 |
| Ground beef 10% | 4.79 | 27.2 |
| Ground beef 20% | 4.18 | 16.5 |
| Ground beef 30% | 3.57 | 10.8 |
| Beef brisket point | 4.24 | 15.9 |
| Lamb shoulder chop | 3.43 | 13.2 |
| Pork tenderloin | 1.87 | 15.6 |
| Pork leg shank | 2.02 | 10.5 |
| Turkey breast | 1.16 | 10.2 |
| Turkey thigh | 2.95 | 25.4 |
| Turkey thigh with skin | 2.60 | 16.1 |
| Veal escalope | 2.56 | 23.7 |
| Veal shoulder | 3.98 | 32.1 |
| Venison | 2.09 | 17.4 |
| Organs | ||
| Beef liver | 4.0 | 29.6 |
| Chicken liver | 2.7 | 22.4 |
| Beef kidney | 1.92 | 19.4 |
| Lamb kidney | 2.24 | 23.1 |
| Beef heart | 1.7 | 15.2 |
| Chicken heart | 6.59 | 43.1 |
| Beef lung | 1.61 | 17.5 |
| Lamb lung | 1.8 | 18.9 |
| Sea food | ||
| Oysters, raw | 22.5 | 334 |
| Eastern oysters, canned | 91.0 | 1338 |
| Pacific oysters, cooked | 33.2 | 204 |
| Wild eastern oyster, cooked | 78.6 | 771 |
| Blue mussel, cooked | 2.7 | 15.5 |
| Whole Prey | ||
| Mouse, neonatal <3g | 1.58 | 16.9 |
| Mouse, juvenil 3-10g | 1.37 | 11.3 |
| Mouse, adult > 10g | 2.21 | 12.9 |
| Rat, neonatal < 10g | 2.36 | 21.4 |
| Rat, adult >50g | 2.11 | 9.7 |
| Quail 1 to 3d | 1.33 | 8.8 |
| Quail 21 to 40d | 1.36 | 8.9 |
| Quail >60d | 2.44 | 14.0 |
| Rabbit stillborn | 2.16 | 18.0 |
| Rabbit 30 to 45d | 3.00 | 21.1 |
| Rabbit >65d skinned | 2.56 | 15.1 |
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] Kane, E., Morris, J. G., Rogers, Q. R., Ihrke, P. J., & Cupps, P. T. (1981). Zinc deficiency in the cat. The Journal of nutrition, 111(3), 488–495.
[5] Mosallanejad, Bahman & Avizeh, Reza. (2012). The Possible Role of Zinc in Excessive Shedding of Hair in two Persian Cats. Comparative Haematology International - COMP HAEMATOL INT. 21.
[6] FEDIAF (2021) Nutritional Guidelines for Complete and Complementary Pet Food for Cats and Dogs.
[7] McDowell, L.R. (2003) Minerals in animals and human nutrition. 2nd Edition. Elsevier Science BV.
[8] Dierenfeld, Ellen & Alcorn, Heather & Jacobsen, Krista. (2002). Nutrient Composition of Whole Vertebrate Prey (Excluding Fish) Fed in Zoos. 7994.
[9] 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.
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.