The Protein Revolution: 5 Game-Changing Points to Consider on Your Pet’s Feeding Package

Protein is an important component in the diet of cats and dogs.

So it is not for nothing that their content is listed in the first place on the package. Have you ever looked at the back of a food package?

And what does the protein content mean – 26%, 30%, or any other?

Pet owners often have questions about the protein content of foods that are listed on the label. And providing sensible answers to such questions can be difficult even for some veterinarians.

Of course, pet owners and veterinarians often pay attention to the protein value on the food label. Despite this, most may not understand of how this number (a protein on the package) is derived and how it should be understood.

To improve pet diets, we all need to understand several important points about proteins in feed.

In today’s article, we are going to talk about how to properly understand the protein information that manufacturers put on food packages/labels.

This article is based on the materials of Rebecca Remillard, Ph.D., DVM, DACVN, a well-known nutrition consultant and veterinarian.

Read in materials:

• What are proteins?
• How do I know the amount of protein in my cat food?
• Crude protein as an estimated value
• Amino acid requirements instead of protein
• What is guaranteed protein adequacy
• Recommendations for protein content as recommended ranges
• Protein requirements for animals with health problems

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What Are Proteins?

To begin with, a little brief overview of what proteins are and what they are “eaten with”.

So, proteins are organic substances of animal and plant origin, which provide support for the cells of any organism.

Scientifically speaking, they are high-molecular-weight organic substances consisting of amino acids linked by peptide bonds.

A protein molecule is very large, for example, compared to the same molecules of sugar or salt, and consists of many amino acids bonded together.

In this way, they form long chains, similar to the way beads are arranged on a string.

Proteins are responsible for the growth, repair, and replacement of tissues.

They perform many functions in the body:

• are necessary for the growth and construction of body cells,
• almost all enzymes and some hormones have a protein composition,
• are actively involved in the production of antibodies and ensure the strength and activity of the immune system,
• are involved in the transport of many compounds.

There are about 20 different basic amino acids that are commonly found in proteins (see table below).

How Do I Know the Amount of Protein in My Cat Food?

You can tell the amount of protein in the food by looking at the back of the package. Manufacturers are required to state the nutritional value (analysis) of the nutrients as a percentage.

For example (taken from a package of one of the dry cat foods):

• Protein28%,
• Fat 20%,
• Fiber 5%,
• Ash 6%,
• Calcium 1,3%,
• Phosphorus 0,8%.

The amount of protein in animal feed should always be listed on the back of the package (see below).

In today’s materials, we are interested in proteins. We will talk about the other elements in separate articles. Although, we wrote a little about carbohydrates earlier.

By the way, the requirements for nutrients are strictly regulated and every manufacturer must follow them.

There are a number of reputable global organizations that are involved in the development of feed requirements.

The best-known are:

• AAFCO — The Association of American Feed Control Officials.
• FEDIAF — European Pet Food Industry Federation.
• NRC — The National Research Council (NRC) is the operating arm of the United States National Academies of Sciences, Engineering, and Medicine 

What these organizations are and what they do you can read in our materials about the International Requirements for Cat Foods.

And we return to the subject of proteins in pet diets.

Point 1

The Amount of Crude Protein on the Feed Label is Only an Estimate

It would seem, take the package and look at the “proteins” listed on the product label. However, the term actually refers to a calculated estimate.

And the big surprise is that feed labels usually indicate crude protein.

Crude proteins are calculated after measuring the nitrogen content of the feed. The idea is that each amino acid (the building block of proteins) contains nitrogen. Thus, by examining the total nitrogen content, the amount of protein in that feed can be determined.

That is, the amount of protein (%) is based on laboratory determination of the total nitrogen content of the feed, which is then divided by the average nitrogen content of the proteins (for industrial feeds it is 16%).

Schematically, the process of determining the amount of crude protein would look like this:

Keep in mind that not all of the nitrogen in the product is in the form of protein. Other ingredients (e.g. carbohydrates, fat, fiber, additives) already contain non-protein nitrogen, which also counts in the total crude protein estimate.

So, back to our proteins on the package.

Keep in mind that pet food labels usually indicate only the guaranteed minimum crude protein (protein) without reference to the protein source. Therefore, this value should not be taken as the actual protein content of the product.

Keep this in mind! In 2007, a compound called melamine was added to wheat gluten and rice protein concentrate. Such a maneuver was supposed to increase the crude protein content of these ingredients, but not at the expense of protein. And melamine contains 67% nitrogen by weight, but no protein.

Point 2

Animals Need Essential Amino Acids, Not Protein

Protein is the most expensive ingredient in any food, whether for pets or humans. Especially high-quality protein from muscle meat is the most expensive part.

Every living organism needs specific essential amino acids (not protein itself). They are necessary for growth, to support pregnancy and lactation, and to prevent disease.

After consuming and digesting dietary protein, animals use the essential amino acids and synthesize the substitutable amino acids that the body needs.

The amount of crude protein on the pet food label provides no information regarding the concentration, ratio, or digestibility of essential amino acids in the product.

And here it is important for all pet owners to understand that there is no “perfect” protein ingredient for dogs or cats.

In fact, it is the different proteins that are needed to meet essential amino acid needs.

Consequently, if the protein ingredient(s) are low or lack the right amino acids, they can be added separately. For example, foods may contain individual synthetic amino acids (methionine, taurine) added to meet the unique needs of cats or dogs.

Keep this in mind! Dry food with a minimum crude protein content of 35% on the label is a good value and exceeds the recommendations for both dogs and cats. However, if the product does not contain the essential amino acid taurine or an adequate concentration of arginine, the food cannot be considered complete.

The amount of crude protein by itself says nothing about, say, taurine or arginine content. High-protein foods do not necessarily meet essential amino acid requirements better than low-protein foods.

Point 3

Protein Adequacy Can Only Be Guaranteed Through Standardized Feeding Tests or Nutritional Analysis

The nutritional value of a product (and its proteins) can be evaluated using standardized animal feeding tests that measure protein bioavailability.

The feed packaging sometimes mentions an “AAFCO Nutritional Adequacy Statement” (AAFCO Statement). It indicates whether the product has been tested for long-term feeding in accordance with the AAFCO recommendations.

The idea is that the test animals must eat the food under study for 26 weeks (about 6 months). If positive, such feed can claim to be “a complete and balanced diet, as confirmed by feeding studies”.

Marking this statement on the product label should provide additional assurance to pet owners as to the overall quality of the product. Actually, through standardized testing, it asserts that the amino acid content was bioavailable and adequate for the health of the pet.

None of these guarantees can be derived from the amount of crude protein.

Specific information about amino acids cannot be listed on pet food labels due to space limitations. However, feed manufacturers can publish them online or in company product manuals.

Point 4

Recommendations for Protein Content in Feeds Are Only Recommended Ranges

It should be understood that the amounts of proteins recommended by the NRC and AAFCO include some safety margin.

This margin is used to account for known negative ingredient interactions, losses, and uncertainties about the various components.

NRC offers 2 types of nutrient recommendations:

• minimum requirements – the necessary amount if the nutrient is readily bioavailable to the animal;
• recommended rates – larger amounts when bioavailability is reduced due to known food interactions.

What is the bioavailability of a substance? It is an indicator that describes the amount of loss. That is, the higher the bioavailability of a substance, the less it will be lost to absorption and use by the body.

Keep in mind that the recommended rates of protein will always be greater than or equal to the minimum.

Take, for example, what the NRC says about proteins.

The minimum protein requirement for healthy adult cats is 40 g/Mcal, but the recommended requirement is 50 g/Mcal (see table). The reason for the differences is that dietary protein sources are not 100% bioavailable from food.

AAFCO, which operates independently of the NRC, generally has a wider margin of safety for protein content in adult dog and cat foods (see table). Note that AAFCO does not list minimum and recommended requirements – they have one value.

Manufacturers of pet food often specify a fairly wide range of protein content (from 15% to 60% dry matter).

These values are generally higher than those recommended by the NRC and AAFCO, even though more protein is not always for the best.

Point 5

Protein Recommendations for Animals With Different Health Problems Vary

The decision to adjust the protein concentration in the diet should be based on an understanding of current protein intake.

In many cases (e.g., weight loss, osteoarthritis, feline diabetes, feline hyperthyroidism, elderly pets with reduced protein metabolism) protein levels above the AAFCO recommendations may be indicated.

Conversely, there are medical conditions in which lower protein levels may be beneficial. For example, a late-stage liver or kidney disease.

It is very important to understand that for any condition, an increase or decrease in protein intake should depend on current protein intake. This should not be done only in relation to NRC or AAFCO values.

Importantly, neither the NRC nor AAFCO recommends specific nutrient levels for medical or health-related conditions.

The recommended amounts of specific nutrients of concern (e.g., fats, potassium) for disease management are usually established by nutritionists and allied professionals and are based on known disease-specific processes.

For example, therapeutic low-protein diets (for kidney disease, liver disease, or urolithiasis) are designed for long-term feeding. They usually contain easily digestible (> 80%) ingredients with good amino acid profiles (e.g. eggs, liver, whey).

This is done intentionally to ensure that essential amino acid needs are met while offering a lower load of total nitrogen (i.e. crude protein). In turn, this reduces the impact on various organs of the body.

Keep this in mind.
Even diets with 10% protein in dry matter, properly formulated, can cover essential amino acids.
As an example, such foods have been used safely for years for dogs with kidney or liver disease.

How Do I Calculate the Protein in the Feed?

Sometimes there is a need to calculate the amount of protein or other ingredients in cat food. This is especially true if two foods, such as dry and wet, need to be compared.

To do a comparative analysis of pet food, the guaranteed analysis data must be converted into dry matter to avoid incorrect conclusions, as if you were comparing apples to bananas.

To account for protein, for example, you need to account for the moisture content on it and recalculate them into dry matter.

Conclusions

Crude protein on feed packaging tells us nothing about the value of protein (neither its amino acid content nor its digestibility).

Therefore, it would be better to avoid using this term, replacing it with an indication of the nitrogen content and amino acid profile. And of course, the important indicators for us would be exactly the content of available amino acids in proteins.

There is no single “ideal” protein value for all pets and at all life stages.

Every pet’s diet should be based on amino acid content, not the amount of protein on the food package.

And, of course, keep in mind that good nutrition is the key to a long life for your pet!

Frequently Asked Questions

Hopefully, now you know more about what the specified amount of protein in animal feed means.

So let’s take it in stride 🐱 and get smarter! And don’t forget to share the information with our other feline colleagues.

And we’re done for the day. Pa!