5 questions about protein in my cat's diet

When it comes to feeding your cat, everyone talks about proteins. But why are they so important? How can I tell if my cat is eating enough protein? Are high-protein kibbles and wet food better? Many questions, but often very few answers (or sometimes wrong ones). At Ziggy, we couldn’t leave you confused. We tell you everything in this article.

1. Why are proteins essential in my cat’s diet?

In the family of carnivores, meet the cat! Your feline friend is a strict carnivore, meaning it cannot live healthily without animal proteins in its diet. A vegan cat does not exist! Or if it does, it’s a rabbit with tiny ears.

These proteins are absolutely necessary because they provide the amino acids your cat needs to synthesize its own proteins. Simply put, once digested in the digestive tract, proteins release amino acids, which then enter the bloodstream. Depending on the organs’ needs, new proteins or amino acids are produced.

Animal proteins are the source of the 11 essential amino acids necessary for your cat’s health.

Among the roughly twenty common amino acids, 11 are essential for cats and must be provided through their diet. These include taurine, arginine, phenylalanine, methionine, valine, leucine, isoleucine, lysine, tryptophan, threonine, and histidine.

All these micronutrients play a crucial role; they contribute to your cat’s proper bodily functions (immunity, growth, digestion, reproduction) and structure (bones, skin, muscles, fur).

Without animal proteins – and thus without these amino acids – your cat would suffer severe deficiencies and would not live long by your side. Taurine deficiency, in particular, causes central retinal degeneration (irreversible blindness), immune dysfunction, and cardiomyopathy.

A cat with insufficient protein intake may also show other clinical signs: neurological disorders (arginine, phenylalanine, threonine deficiency), weight loss or even anorexia (phenylalanine, methionine, leucine, valine, lysine, tryptophan, threonine, and histidine deficiency), poor coat quality such as greasy fur or dull fur (methionine, isoleucine deficiency).

Minerals, lipids, and vitamins

Be careful, your furry friend is indeed a strict carnivore, but cannot consume only proteins. It also needs other nutrients in its food.

For good health, kitty must also get lipids (essential fatty acids), minerals (calcium, phosphorus, magnesium, potassium, sodium, etc.), vitamins (especially B vitamins), and fibers necessary for good digestion. Fibers are provided, for example, by vegetables.

A diet made solely of meat can also cause deficiencies. As explained in our article on common myths about feeding your cat, a cat deficient in calcium, for example, may have demineralized skeletons, easily fractured bones, a weaker spine, and over time, an abnormal S-shaped curvature.

2. What are my cat’s protein needs? And how do I know if my cat eats enough protein?

Considering factors such as neutering, physical activity, and age, the estimated protein requirement for an adult cat is “between 5.2 and 6 grams of protein per kg of optimal body weight per day to maintain lean body mass,” explains Dr. Géraldine Blanchard, a feline nutrition specialist who formulated our Ziggy kibbles and delicious pâtés. This recommendation is supported by a study by Dr. Laflamme (2013). Note this need may increase in some cats, especially pregnant females and kittens.

As caring cat parents, it’s not always easy to know if your little kitty is eating enough protein. One useful indicator is the protein-to-calorie ratio (PCR). This ratio measures the concentration of protein relative to the calories provided by the food, helping precisely estimate the amount of protein relative to the energy requirement.

For our cats, whose protein needs are estimated between 5.2 and 6 grams per kg of optimal weight, the ideal PCR should be above:

• 75 g/mCal for an intact (active) cat
• 87 g/mCal for a neutered or sedentary cat
• 100 g/mCal for a neutered and sedentary cat

Our Ziggy adult cat pâtés for neutered cats, for example, have a PCR of 109.8 g/mCal. The pâtés for intact adult cats have a PCR of 83.3 g/mCal.

Unfortunately, this protein-to-calorie ratio is not always indicated on cat (and dog) food packaging.

How to calculate the protein-to-calorie ratio (PCR)?

The formula is:

% crude protein / Metabolizable Energy (ME) x 1000

For example, a pâté for neutered adult cats sold in supermarkets:

• Crude protein: 7.6%
• Metabolizable Energy (ME): 73 kcal/100g

Calculation: 7.6 / 73 x 1000 = 104 g/mCal

However, don’t rely 100% on the PCR. This ratio is quantitative, not qualitative! It does not provide any information about the quality of proteins used in your cat’s kibble or pâté.

Pssst: Not sure how much kibble and pâté to give your cat? Feel free to use our calculator.

How to calculate the protein-to-calorie ratio (PCR)?

The formula is as follows:

% crude protein / Metabolizable Energy (ME) x 1000

Let's take the example of a wet food for sterilized adult cats sold in supermarkets.

• Crude protein: 7.6%
• Metabolizable Energy (ME): 73 kcal/100 g

This gives: 7.6 / 73 x 1000 = 104 g/mCal

However, you should not rely 100% on the PCR. This ratio is quantitative, not qualitative! It does not give you any indication of the quality of proteins used in your whiskered friend's kibble or wet food.

Pssst: Don't know how much kibble and wet food to give your cat? Feel free to use our ration calculator 😻. It also tells you your cat's energy needs (Kcal/day), based on age, weight, and activity.

3. My cat's kibble and/or wet food shows a high protein content. Is that good?

A high protein content seems reassuring at first. But beware, it can be misleading!

Know that most wet cat foods do not contain noble offal or real muscle pieces, but rather reconstituted meat (a mix of animal and plant proteins), mechanically separated meat (MSM), or animal meals.

What is mechanically separated meat (MSM)?

Let's refer back to our little glossary. It is a product "obtained by removing, using mechanical means, meat from poultry bones or carcasses. Obtained after deboning, this product may contain bone, cartilage or marrow residues, unlike minced meat or ground meat."

And what about animal meals?

These are obtained from mechanically separated meat. The mixture of carcass and meat is then ground into meals.

A high protein content therefore does not mean much. There is no benefit to giving your cat a protein-rich food if it actually contains carcass or collagen. Especially since these proteins provide no nutritional benefit to your little cat!

By ingesting these proteins, your whiskered friend will not use them for metabolism. Even his small body does not find them of sufficient quality! Amino acids will be eliminated through urine, and the more your cat consumes these proteins, the more it will strain its kidneys. This can lead to chronic kidney disease in the long term.

The PCR also shows that a high protein content means nothing by itself. Let's take the example of two dry foods for sterilized adult cats with the same protein content:

Food A:

• Crude protein: 35%
• Metabolizable Energy: 350 kcal/100 g

Food B:

• Crude protein: 35%
• Metabolizable Energy: 400 kcal/100 g

PCR of Food A: 100 g/mCal

PCR of Food B: 87.5 g/mCal

For a sterilized adult cat, Food A is closer to its needs.

Animal proteins vs plant proteins

Also watch out for plant proteins. For economic reasons, many manufacturers use them.

Recall that animal proteins mainly come from meat, offal, fish, and eggs. Plant proteins mostly come from cereal grains (wheat, rice, corn, barley) and legume seeds (peas, soy).

Unlike animal proteins, plant proteins do not provide all essential amino acids. They cannot meet our cats' needs. Taurine and arginine are notably absent from plant sources. As we have seen: a deficient cat risks serious health problems.

4. How to check the quality of proteins used in my cat's food?

The quality of ANIMAL proteins is fundamental to keeping your little cat healthy. To check the quality of proteins used, some indicators can help you make the right choice.

Know that protein quality depends on their ability to provide essential amino acids to cats. In feline nutrition, it is the protein/phosphorus ratio or protein-to-phosphorus ratio (PPR) of the food that gives clues about the quality of proteins used in manufacturing.

High-quality protein sources, or with high biological value (percentage of protein retained by the body), have a high ratio (above 35). These include fish, meat, eggs, and offal.

Conversely, very low-quality protein sources (low biological value) have a low protein/phosphorus ratio (below 25). This is the case with cereals, carcasses, and bones. Since phosphorus is mainly found in bones, a low PPR shows that a large amount of carcass or bone has been added in your cat's kibble or wet food.

How to calculate the protein-to-phosphorus ratio (PPR)?

To determine this ratio, simply divide the crude protein percentage by the phosphorus percentage. For example, if your cat's wet food has 10% crude protein and 0.41% phosphorus, that makes 24.3. Not great...

One problem: few manufacturers list phosphorus content on their products. This information is not mandatory. They have every right not to show it. In this case, you can rely on the ash content, which is mandatory under European regulations.

This value indicates the amount of minerals (calcium, phosphorus, magnesium, etc.) present in your cat's food after complete combustion. To calculate it, the food is entirely burned. The residue is the crude ash content, which you can find in the analytical constituents on the back of the package or can.

Ash content is an indirect quality indicator. The higher it is, the more carcass has been added.

Note however that minerals, including phosphorus, remain essential for our cats. They ensure growth and maintenance of hard and soft tissues, and the production of enzymes and hormones. It's all about balance.

In wet food, for example, one looks for crude ash content between 1.25% and 2.5% for a healthy adult cat.

5. What about proteins at Ziggy?

At Ziggy, quality is our motto.

In our wet foods for cats, you will not find MSM, animal meals, or reconstituted meat. We only use animal proteins from muscle and noble offal of great nutritional richness, highly digestible for our cats.

All our recipes are formulated by Dr. Géraldine Blanchard, a world-renowned feline nutrition expert. We assure you she is very meticulous! Every ingredient has been checked and analyzed by her.

Our wet and dry foods (grain-free) meet the nutritional needs of all cats. The first ingredient in each recipe is always an animal protein source (+50%). To learn more, feel free to check our ingredient list. We are fully transparent 😺

Another advantage: our foods are also low in carbohydrates. Our wet foods contain less than 2% carbohydrates. They also do not contain cereals, tubers, or legumes.

Carbohydrates are indeed another factor to consider when choosing your cat's food. And rightly so: our cats are not adapted to digest, absorb, and metabolize large amounts of carbohydrates.

High consumption can also cause overweight, and it has been suggested that foods too rich in carbohydrates may increase insulin secretion demand and thus predispose to diabetes mellitus. We explain more in our article on carbohydrates in your cat's food.

6. (Bonus). Can a cat be allergic to proteins?

Many of you wonder about this. Although essential, some specific proteins found in beef, chicken, fish, or cereals may be poorly tolerated by some cats.

Food allergies are quite rare in our furry friends but do exist. They can manifest as vomiting, digestive disorders, itching, or ear infections. These signs can also indicate other diseases.

If you have any doubt, consult your veterinarian to determine if it is an allergy or another illness. If so, your vet will help you conduct an exclusion diet for your cat. This involves excluding one by one the proteins most commonly responsible for allergic reactions in cats.