Is a food with more protein automatically better?

No. Crude protein measures nitrogen, not the quality or digestibility of the protein source. A high figure achieved with poorly digestible raw materials delivers less than a lower figure from good quality protein. What matters is the amino acid profile, digestibility and suitability for the life stage, and in animals with kidney or liver disease the requirement is set with the vet, not from the label.

What exactly does meat and animal derivatives mean?

It is an ingredient category defined in European legislation that groups parts of land animals, including organs and tissues other than muscle, many of which are nutritionally sound. It does not in itself indicate low quality, but it does not tell you which species the material came from. If you are working through a suspected adverse food reaction and need to exclude a specific protein, you need a product with open ingredient declaration.

Why can I not find kilocalories on the label?

Declaring metabolisable energy is not always mandatory, so many manufacturers omit it and provide only a table of recommended grams. You can estimate it from the analytical constituents with the modified Atwater factors, or ask the consumer helpline, which will usually supply it. Without that number you cannot calculate a ration from the animal's energy requirement.

Are grain free foods better for dogs and cats?

There is no demonstrated benefit to removing grain in healthy animals. When cereals come out, the carbohydrate share is covered by legumes, potato or tapioca, so starch content can stay much the same. The choice makes sense in a documented adverse reaction to a specific ingredient, which needs identifying with an elimination diet rather than assuming.

How do I compare a wet and a dry food I want to feed together?

Convert both to dry matter to compare nutrients, and use kilocalories per gram to calculate the ration. In a mixed diet you first decide the total energy requirement, then decide what share the wet food covers and what share the dry one covers, and finally convert each share into grams using the respective energy densities.

Nutrition10 min readUpdated on July 25, 2026

How to actually read the label on a complete pet food

Analytical constituents, dry matter, ingredient lists and additives: how to compare two very different products fairly and see what you are really buying.

Audience: Pet owners
Species: Dog, Cat
Scope: European Union, Italy, Valid everywhere

Anyone comparing two foods by the percentages printed on the pack almost always reaches the wrong conclusion, and not through carelessness: declared percentages refer to the product as it is, water included, so a wet food at 80 per cent moisture and a kibble at 8 per cent are simply not comparable numbers. On top of that sits an ingredient list written to precise but little known rules, which allow generic categories instead of specific raw materials. Reading a label properly takes four steps in sequence, each with a calculation or a checkable criterion. This page puts them in order, with the numbers you need to run them.

Complete or complementary: the first thing to look for

In the European Union a pet food label must state whether the product is a complete or a complementary feed. This is not a formality: a complete food is formulated to cover every nutritional requirement on its own for the stated life stage, while a complementary food covers only part and must be combined with something else. Many products people treat as everyday food, including several single protein wet lines and almost all treats, are complementary.

Alongside that statement, look for the target species and the life stage. A growth food has different calcium, phosphorus and energy density profiles from an adult maintenance food, and in large breed puppies excess calcium is not a detail but a documented orthopaedic risk factor. If the life stage does not appear on the label, that information is missing and should be requested from the manufacturer.

Analytical constituents and what they leave out

The analytical constituents are the small table listing crude protein, crude fats and oils, crude fibre and crude ash, plus moisture when it exceeds the declared threshold. The word crude means the figure comes from a standard analytical method that quantifies a class of substances, not their quality: crude protein is derived from total nitrogen, so it cannot distinguish a highly digestible protein from one the animal barely uses.

What each analytical constituent measures and what it misses
Constituent	What it quantifies	What it does not tell you
Crude protein	Total nitrogen converted to protein	Digestibility, amino acid profile, origin
Crude fat	Extractable lipid fraction	Omega 6 to omega 3 ratio, oxidation status
Crude fibre	Insoluble residue after acid and alkali treatment	Soluble fermentable fibre, the part that feeds the microbiota
Crude ash	Total mineral residue after incineration	Which minerals and in what ratio, for example calcium to phosphorus
Moisture	Water content of the product	Nothing about nutrition, but it changes every other number

One value almost never listed among the analytical constituents, but easily derived, is nitrogen free extract, which in practice means digestible carbohydrate. Subtract from one hundred the sum of protein, fat, fibre, ash and moisture. In a kibble with 26 protein, 14 fat, 3 fibre, 7 ash and 8 moisture, the difference is 42: that figure, which nobody prints on the pack, is often the largest single component of the product.

Dry matter: the step that makes products comparable

No comparison between foods means anything until the water is taken out of the equation. The calculation is simple: divide the declared value by the dry matter, meaning one hundred minus moisture, and multiply by one hundred. The result is how much that nutrient weighs within the solid part of the product, and it is the only number that lets a kibble and a can sit side by side.

The same calculation on a dry and a wet food: front of pack percentages mislead
Figure	Kibble	Canned wet food
Protein declared as fed	26 per cent	9 per cent
Declared moisture	8 per cent	80 per cent
Dry matter	92 per cent	20 per cent
Protein on dry matter	about 28 per cent	45 per cent
Conclusion	Less protein rich than it looks	Far more protein rich than it looks

The same conversion applies to fat, fibre and ash before drawing any conclusion. It is also why claims such as high protein on a wet food should always be checked: in most cases the number on the front of the pack is the as fed figure, while the useful comparison is on dry matter.

The ingredient list: open declaration or categories

Ingredients are listed in descending order of weight, but the manufacturer can choose between two ways of declaring them. Open declaration names specific raw materials, for example chicken meat or rice. Category declaration uses generic groupings such as meat and animal derivatives or cereals, which are legitimate but do not reveal which animal species or which cereal was used.

Weight order: the first ingredient outweighs the second, but the weight is measured before processing. Fresh meat carries a lot of water and loses most of its weight in cooking, so appearing first does not mean being the main component of the finished food.
Splitting: listing rice, rice flour and rice bran separately pushes each entry further down the list, even when their sum exceeds the ingredient in first place.
Generic categories: meat and animal derivatives is a permitted category and does not imply poor quality, but it prevents you from excluding a specific protein, which is decisive in a suspected adverse food reaction.
Highlighted mentions: when a raw material is called out on the label or in the product name, its percentage in the product must be stated.

Thresholds used by the European labelling code of good practice for ingredient claims
Wording	Minimum amount of the named ingredient
Flavour, flavoured with	Under 4 per cent, enough to characterise the flavour
With	At least 4 per cent
Rich in	At least 14 per cent
Dinner, menu, meal made with	At least 26 per cent
All, one hundred per cent	Only the named ingredient, excluding water and additives

These thresholds explain how two products that appear to say the same thing can contain wildly different amounts. A wet food with chicken and a chicken flavoured wet food belong to two separate categories, and the gap is an order of magnitude. Checking the exact wording, and the percentage that must accompany a highlighted ingredient, tells you far more than any picture on the pack.

Additives and the nutritional statement

Additives are grouped into categories, and their presence on a label is not in itself a flaw: nutritional additives are the vitamins, minerals and trace elements added so the food reaches the profile required of a complete feed. Without them no industrial formulation would genuinely be complete. They are usually declared per kilogram of product, and in a complete food it is worth checking at least vitamin D, vitamin E, copper, zinc and iodine, whose safety margins are narrower.

Nutritional additives: vitamins, amino acids, trace elements. In cats taurine is essential and must be present in the formulation, since the species cannot synthesise enough of it.
Technological additives: preservatives, antioxidants, thickeners. Antioxidants protect fats from going rancid, and their complete absence shortens shelf life considerably.
Sensory additives and colourants: they act on palatability and appearance and add no nutritional value.
Zootechnical additives: these include, for example, microorganisms intended to stabilise the gut flora.

The statement worth more than all of these is the one declaring that the food meets recognised nutritional requirements for the species and life stage, referencing the European industry guidelines or the North American profiles. Stronger still is a statement that the product has passed feeding trials, because compliance is then not merely calculated from the formula but verified in animals.

Energy density and the suggested ration

The single most useful figure for daily management is metabolisable energy, expressed in kilocalories per one hundred grams or per kilogram. Not every label carries it, but it can be estimated from the analytical constituents using the modified Atwater factors for pet food: 3.5 kcal per gram of protein, 8.5 per gram of fat and 3.5 per gram of nitrogen free extract.

Work out nitrogen free extract
Subtract from one hundred the sum of declared protein, fat, fibre, ash and moisture. In the earlier example, with 26, 14, 3, 7 and 8, the answer is 42.
Apply the factors
Multiply 26 by 3.5, then 14 by 8.5, then 42 by 3.5. You get 91, 119 and 147 kilocalories per one hundred grams.
Add up and scale to the kilogram
The total is 357 kilocalories per one hundred grams, roughly 3570 kilocalories per kilogram. It is an estimate rather than an analytical value, but it is good enough to compare two products.
Check it against the suggested ration
Multiply the grams given in the feeding table by the energy density and see how many kilocalories that comes to. Manufacturer tables are built on average requirements and tend to overestimate for neutered and sedentary animals.

Feeding instructions on the pack are a starting point, not a prescription. Read them as a range and correct them against the real animal, checking weight and body condition every two or three weeks in the early stages. A product with high energy density needs small portions, and at small portions the error of a scoop becomes proportionally larger: weighing the ration on kitchen scales removes a discrepancy that adds up over a month.

Frequently asked questions

Is a food with more protein automatically better?: No. Crude protein measures nitrogen, not the quality or digestibility of the protein source. A high figure achieved with poorly digestible raw materials delivers less than a lower figure from good quality protein. What matters is the amino acid profile, digestibility and suitability for the life stage, and in animals with kidney or liver disease the requirement is set with the vet, not from the label.
What exactly does meat and animal derivatives mean?: It is an ingredient category defined in European legislation that groups parts of land animals, including organs and tissues other than muscle, many of which are nutritionally sound. It does not in itself indicate low quality, but it does not tell you which species the material came from. If you are working through a suspected adverse food reaction and need to exclude a specific protein, you need a product with open ingredient declaration.
Why can I not find kilocalories on the label?: Declaring metabolisable energy is not always mandatory, so many manufacturers omit it and provide only a table of recommended grams. You can estimate it from the analytical constituents with the modified Atwater factors, or ask the consumer helpline, which will usually supply it. Without that number you cannot calculate a ration from the animal's energy requirement.
Are grain free foods better for dogs and cats?: There is no demonstrated benefit to removing grain in healthy animals. When cereals come out, the carbohydrate share is covered by legumes, potato or tapioca, so starch content can stay much the same. The choice makes sense in a documented adverse reaction to a specific ingredient, which needs identifying with an elimination diet rather than assuming.
How do I compare a wet and a dry food I want to feed together?: Convert both to dry matter to compare nutrients, and use kilocalories per gram to calculate the ration. In a mixed diet you first decide the total energy requirement, then decide what share the wet food covers and what share the dry one covers, and finally convert each share into grams using the respective energy densities.

What to do next

Pick up the pack you are using now and check three things: that it declares a complete food for the right species and life stage, what the protein figure becomes once converted to dry matter, and how many kilocalories sit in one hundred grams. If energy is not declared, estimate it with the modified Atwater factors or ask the manufacturer. With that number you can finally build the ration from your animal's requirement instead of a generic table.