Supplements in NRC Recipes
Are Supplements "Necessary"?
People are sometimes taken aback when they see that NRC recipes have supplements in them. (Typical NRC recipe has 3-6 supplements) This is understandable, especially since the popular ratio diets (80/10/10) claim that raw, on its own, is nutritionally complete and balanced (if you want more information on why a ratio diet is not balanced, see this article).
Just looking at NRC diets however, the number of supplements per recipe can vary widely, from 1-2 supplements, to 13+. This article goes through the several factors that play a role in how many supplements are needed in a recipe to make it complete and balanced.
As a nutritionist and believer in homemade diets, I am always going to advocate for whole food sources for nutrients, whenever possible. However, ethically and professionally, my goal is to meet the animal’s nutritional needs using whatever is available to the owner without breaking the bank – whether that’s whole foods or supplements. For dogs with health conditions, low energy requirements or other food restrictions, my priority will be a nutritionally sound diet that works for the dog, and this often includes supplements.
Lower Caloric Intakes
The amount of nutrients dogs get from food is directly related to how much food they eat. The typical suburban or urban dog has fairly low to moderate energy levels, and doesn’t have high caloric needs. This means that their diets should have less calories, thus less food, which results in less overall nutrients.
This means that even if you are using nutrient dense food, the less food you can use due to calorie restrictions, the less nutrients the overall diet has.
NRC uses energy “factors” to determine a dog’s caloric intake.
- 70-90 – low: a typical low activity dog is fairly sedentary, with 1-2x 15-60 minute, non-arduous walks per day. (Senior dogs may be even lower)
- 90-110 – moderate: a typical moderate activity dog is generally active, goes on 1-2x 45+ minute arduous (hiking, running) walks per day.
- 110-130 – high: a typical high activity dog is a working dog or participates in sports
These factors are also affected by breed. Some breeds have generally higher or lower energy levels.
The best way to determine your pet’s caloric intake for maintenance is to assess their current daily intake. The activity guidelines above are general and your individual dog’s caloric needs may be higher or lower despite meeting the activity category.
When formulating an overall recipe, this means that the less calories you have, the more you will need to formulate using lean meats (less than 5% fat) and using plenty of nutrient dense cuts like organ meats. This will help you maximize the amount of nutrients you have per calorie.
Example - 45lb Dog
Let’s look at a recipe based on skinless turkey thighs.
Turkey thighs provide 108kcal and 2.6mg of zinc per 100g.
A low energy 45lb dog with an energy factor of “80” would need 765kcal. A moderate energy 45lb dog with an energy factor of “110” would need 1050kcal. A 45lb dog, of both energy levels, needs at least 19.2mg of zinc per day.
765kcal of turkey thighs provides 18.3mg of zinc, while 1050kcal of turkey thighs provides 25.2mg of zinc. This means that 765kcal of food would not meet nutrient needs for zinc for the 45lb dog, but 1050kcal of food would.
Formulating With Limited or Accessible Ingredients
With pets with food intolerances or allergies, ingredients may be limited. Or perhaps you live in an area without access to a variety of meats or organs; or perhaps you prefer to formulate using specific meats to keep costs low.
All of these factors will affect the nutrients available in the a recipe because not all meats are equal. Some cuts will be higher in certain minerals, fatty acids or vitamins than others, which means that when your options are limited, there is less wiggle room in formulation.
When dealing with senior, weight loss or low activity/energy pets, the fat content of the food plays the biggest factor. Fats are a necessary part of the diet and do provide essential fatty acids, but they do not provide amino acids, minerals or vitamins in significant amounts. So when you use fattier cuts of meat, you end up with less nutrients per calorie.
The fat content of meat can be fairly deceptive. For example, let’s look at the fat content of “lean” ground beef with 10% fat.
Ground Beef 10% fat – 100g
- Energy: 176kcal
- Water: 69.5g
- Protein: 20g
- Fat: 10g
This means that even a “lean” meat like 10% ground beef provides more fat than protein on a calorie basis.
Below is an analysis of 10% ground beef vs 5% ground beef, per calorie. You can see that per calorie, the 5% ground beef provides significantly more minerals and vitamins.
Ground Beef 10% fat – per 1000kcal
- Iron: 12.7mg
- Zinc: 27.2mg
- Pantothenic Acid: 3.4mg
Ground Beef 5% fat – per 1000kcal
- Iron: 17.4mg
- Zinc: 37.2mg
- Pantothenic Acid: 4.8mg
If a recipe has more fat from fat dominant cuts like 10% ground beef, it will have less minerals and vitamins simply because minerals and vitamins are not found in significant amounts in fats.
This is not always a problem. For pets with higher energy levels, it is entirely possible to have a higher fat recipe and still meet all nutrient requirements. However, if you have a lower energy pet, using only fatty cuts will be a challenge when it to comes to meeting nutritional requirements.
Organs are the most nutrient dense cuts you can include in a recipe. If you are not able to use organs in the recipe, your recipe will need supplementation. For example, there is no variety of base meats that can make up for the lack of liver in a recipe (for retinol content).
If you are not able to use any organs, the recipe will need supplementation in copper and vitamin A – and sometimes iron, selenium, and b vitamins.
Each type of organ also provides a unique boost of nutrients.
- beef or lamb liver: copper
- chicken or turkey hearts: linoleic acid
- liver: Vitamin A
- kidneys: selenium and b vitamins
- spleen: iron
For example, if you are not able to source beef liver but can use chicken liver, you may not need a Vitamin A supplement, but you will need to supplement copper.
Pork meat is rich in selenium and thiamin (B1). Recipes without pork will often need to supplement B1 unless the dog is very high energy.
This can be supplemented with a thiamin supplement or a B-complex.
Beef (or Oysters)
Beef and oysters are rich in zinc, which tends to be low in homemade diets. If a recipe does not include either ingredient (beef must be the majority of the meat), the recipe will require a zinc supplement.
Poultry, or fattier pork cuts, provide a great source of linoleic acid. A lean red meat recipe, such as one based on beef or venison, will need supplementation in this essential fatty acid.
Using Nuts, Seeds and Plants
There are many foods touted for being “rich” in microminerals or hard to find vitamins like Vitamin E. But when evaluating these sources, you do have to consider the reliability of the analysis available, the bioavailability of the nutrient from the food, and how nutrient dense the food is.
There has been a lot of talk lately about “superfood” plants like wheatgrass, that are touted for being nutrient rich, especially in Vitamin E.
However, there is often no reliable nutritional analysis for these ingredients – analyzed across multiple samples from different suppliers. This means that there is often great variance between available nutritional profiles – and many of those profiles do not include any sources or citations.
This is a problem because if you are relying on this type of ingredient for almost all your contribution to a single nutrient, like Vitamin E, there’s a much greater risk for the diet in the bowl to be nutritionally different from the diet on paper.
When formulating diets, I strongly recommend using ingredients with known, reliable testing and analysis. In cases like this, I would prioritize a certainty in having the correct amount of an essential nutrient in the diet than prioritizing only using whole foods.
When discussing bioavailability and absorption, we’ll focus on iron.
“The absorption and bioavailability of Fe in dogs can vary enormously, from close to 100% to less than 10% depending on the ionic form of Fe in the diet, Fe status, dietary Fe concentration, and several other factors. ” (NRC 2006)
This is the simplest reason why I do not recommend relying on plant matter like spinach to provide a boost in iron in recipes. Non-heme iron is not as well used in dogs, which means that even if you include it in the diet, it may not actually be used properly by the dog.
Iron is an easy example, due to the clear distinction between heme and non-heme iron, but bioavailability and absorption is a factor to consider for all minerals. Each mineral has its own sets of interaction with other nutrients, has many different forms (include multiple organic and supplemental forms), and concentration considerations that can all affect how well the nutrient can be used by the animal.
In raw diets, it has become more popular to use nuts and seeds to provide manganese and Vitamin E. While it’s true that these foods have more vitamin E/manganese than most meat cuts, there is still not enough to meet the nutritional requirements for dogs.
For example, let’s look at a 45lb dog.
A 45lb dog would need 9.6mg of Vitamin E*.
Almonds have 25.6mg of Vitamin E per 100g (compared to ground beef, which has 0.17mg). So in order to meet the basic Vitamin E requirement, you’d need to feed 37.5g (~1.3oz) of almonds. This would be 217kcal of just almonds in one day – about 20% the daily caloric requirements for a moderate energy dog.
The story for manganese is similar – we’ll look at pumpkin seed, as they are often recommended for manganese. A 45lb dog would need 1.5mg of manganese a day.
Pumpkin seeds have 4.5mg of manganese per 100g (compared to ground beef, which provides 0.01mg). So in order to meet the manganese requirement, you’d need to feed 33g (~1.2oz) of pumpkin seeds. This would be 190kcal of just pumpkin seeds – again almost 20% of the daily caloric requirements for a moderate energy dog.
So although nuts and seeds tend to be nutrient dense and provide much more Vitamin E and manganese than typical meat, there just isn’t enough to meet the nutritional requirements for dogs in a reasonable recipe (aka, having 40% of the calories provided by nuts and seeds would not be recommended).
* this basic requirement does not factor in the additional Vitamin E that is nutritionally required and recommended with increased PUFAs, such as omega 3 fatty acids. Most dogs fed a homemade diet will need more Vitamin E in their diet than the base requirement
- Dogs with lower caloric needs may not be able to obtain enough nutrients from food because of the calorie restrictions
- Meat that has more calories from fat than protein (anything that’s 10% fat or greater) has less nutrients per calorie than leaner cuts.
- Recipes without organs will need supplementation. Base meats do not provide enough or the same nutritional profile as organs.
- Beef, pork and poultry are each rich in different nutrients. Recipes without specific proteins may need supplementing in the lacking areas.
- I would recommend using a supplement rather than a whole food with uncertain nutritional analysis.
- Nuts and seeds do have more Vitamin E and manganese than meat, but still does not provide enough to meet requirements.