The Essential Guide To Cat Food Diets: What You Need To Know?

When admiring our serenely sleeping cats curled up cosily at the end of the bed it’s hard to rationalise that these beautiful elegant creatures who have become affectionate companions and confidants over the years are in reality lean, mean killing machines when it comes to their eating habits.
For most cat owners, the fact that we are actually harbouring a skilled assassin is something we would rather turn a blind eye to. However, the impressive features of a natural born predator are hard to deny; strong agile bodies with lightning reflexes, stealthy silent gait, razor sharp claws, long canine teeth, excellent night vision, highly attuned hearing and a superior sense of smell. Acknowledging the glaringly obvious truth about these unique creatures we share our lives with is fundamental to understanding all aspects of their healthcare. So why does this often get forgotten when it comes to the most essential of topics – nutrition!

Acknowledging the glaringly obvious truth about these unique creatures we share our lives with is fundamental to understanding all aspects of their healthcare. So why does this often get forgotten when it comes to the most essential of topics – cat food nutrition!

WHAT ARE YOU FEEDING YOUR CAT?

Currently 70% of cat owners feed a commercially prepared diet to their cat, of which half feed a mix of wet and dry food; the other 30% of owners feed table scraps, raw diets or real prey based plans.
Raw and prey diets are potentially very biologically appropriate. However, home prepared diets are notoriously difficult to balance correctly and can be time consuming and inconvenient for most. Worryingly, a recently study in the US found 82% of home prepared diets to be deficient in multiple nutrients. Even so, some commercial diets are just as inappropriate; they may well balance better on paper but it only takes a glance at the back of a packet of some commercial diets to highlight their inadequacies.

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For most cat owners, the fact that we are actually harbouring a skilled assassin is something we would rather turn a blind eye to.

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For example, take the two market leading dry food brands; the analytical constituents read 30-32% protein, 10% fat and 7.5-8.5% ash. What the manufacturer doesn’t need to declare is the carbohydrate content. Most of these dry diets are over 40% carbohydrate and rely on the carbohydrate to create the kibble structure. So why should this be a concern?

ARE CATS CARNIVORE OR OMNIVORE?

Cats are biologically different to us, they are classified as obligate carnivores. If you are a ‘Carnivore’ you derive your energy and nutrients from a diet exclusively or mainly from animal tissue. If you are an obligate carnivore you depend solely on animal tissue as opposed to a facultative carnivore that, in the absence of meat, can choose to use non-animal sources for their nutritional requirements. In contrast humans are classed as omnivores, deriving their energy from a variety of food sources, and dogs are a topic of controversy and can be classified as either omnivore or facultative carnivores.
The domestic cat’s natural diet consists of small rodents and mammals. On average a prey item is 62% animal derived protein, 10% fat with 14% ash, which is mainly mineral content from bone (see the table below).

This protein rich diet has caused obligate carnivores to evolve with completely different biochemical pathways for processing food and metabolising nutrients when compared to other species we are familiar with such as ourselves or dogs.

CAT’S NEED PROTEIN FOR ENERGY, NOT CARBOHYDRATES!

The universal source of energy to all cells in any creature is glucose. For humans and dogs glucose is readily available from breaking down the carbohydrate in our diets. However, for carnivores their diet of fat and protein requires them to obtain glucose in a different way. Hence cats have well developed pathways to convert the building blocks of protein, amino acids, into a source of glucose. These pathways exist in humans and dogs but they are part of a collection of pathways to create energy that can be altered dependent on the type of food ingested. For cats, even when a cat has not consumed any protein, their body cells still demand a source of amino acids for energy and, in the absence of dietary protein, they have to start utilising existing body protein, i.e. muscle mass, to maintain normal cell function.
Cats naturally consume a high amount of protein in their diet, 62% if they consume a mouse. Comparing this with the commercial diet at 30% it doesn’t take an expert nutritionist to identify a potential discrepancy!

DON’T ALL UK BASED CAT FOOD PRODUCTS CONTAIN PROTEIN?

Moreover, the other important question that needs to be considered is where the protein originates from. Protein in a diet can come from animal tissue but is also found in many vegetables and grains. The only way of determining the source of protein is by analysing the composition (ingredient) list on the back of the packet. The list is ordered by weight in descending order, so to satisfy a cat’s biological requirements, a source of meat based protein should be first on the list. For the two diets in our example the first three ingredients read: cereals, animal and meat derivatives (10%), vegetable protein extracts. Therefore the protein declared in these diets is largely derived from non-animal sources. Other than the obvious fact that I have never witnessed a cat with a desire to stalk vegetables, why does this matter?

CATS NEED ANIMAL PROTEIN FOR HEALTH REASONS

Cats require specific amino acids and vitamins in their diet which are essential for normal cell function; some of these can only be obtained naturally from animal tissue. Arginine, Taurine, Cysteine and Methionine are amino acids used in lots of important processes in mammals but cats have to rely on a dietary source making them essential; this is not the case in dogs and humans as they can synthesis these molecules from others. For cats this process is not efficient and their daily requirements are much higher, consequently they utilise them faster than they can be created. Deficiencies can cause serious disease, for example taurine deficiency can cause heart disease and blindness. Commercial diets have to follow strict guidelines to ensure that these molecules are present in adequate amounts and in cases where levels are inadequate, supplement them artificially. Surely the more logical and natural approach is simply to feed what the cat naturally requires- meat based protein!
How many of us have seen a black cat that has a reddish brown tinge to their coat? This is something that many of us may have observed in passing without realising but is a classic example of the effects that a diet deficient in meat can have. Tyrosine is an amino acid only found in animal tissue that cats can’t synthesise themselves. However it is not a necessity for body function and therefore is not a regulated requirement to be supplemented in commercial diets. Tyrosine is a key component of the pathway that creates melanin, the black pigments responsible for their coat colour; so in a deficient state a black cat turns brown.

WHERE DOES YOUR CAT GET THEIR PROTEIN FROM THEIR DIET?

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Cats are biologically different to us, they are classified as obligate carnivores.

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Even when animal protein is included in a diet the majority comes from rendered sources. Rendered meat or more commonly named ‘meal’ comes from animal tissue that has been heated for a prolonged time at extreme temperatures and pressures to remove the fat. Rendered meat is on average only 75% digestible. This means that for every 10g of rendered meat consumed only 7.5g can be utilised by the body. When you compare this to some of the new technologies using fresh meat as an ingredient, with 96% digestibility, this protein source certainly looks to be a more favourable ingredient. Furthermore, digestibility is affected by the carbohydrate content in the diet; the higher the carbohydrate content the less digestible the protein. There are several factors contributing to this but predominately carbohydrates accelerate gut transit hence reducing the time available to digest protein in the diet.
More importantly on this topic, as illustrated by the figures above, a cats natural diet does not contained large amounts of carbohydrate, therefore cats have evolved with a reduced ability to process and utilise carbohydrates.

TOO MANY CARBOHYDRATES IN COMMERCIAL CAT FOOD CAN CAUSE OBESITY IN CATS

The process of breaking down food is carried out by specific molecules called enzymes. Different enzymes are responsible for breaking down different types of food. Amylase is an enzyme responsible for carbohydrate breakdown; this is present in saliva and is then also secreted by the pancreas gland in both dogs and humans. Cats possess no salivary amylase and have very limited levels of pancreatic amylase so have reduced capacity to deal with this type of food.
Cats can process carbohydrate to some extent and once broken down they can use simple sugars very efficiently, however, they have limited ability to store them for future use. In a dog or human excess sugar is stored in the liver as a large chain of sugars in a molecule called glycogen; this can be readily broken down if the animal suddenly needs a source of energy. A cat’s biochemical pathways are not efficient at storing sugars in this way, instead any excess sugars are stored by converting them directly to fat which in turn predisposes cats to weight gain. This process is slower and can lead to prolonged periods of hyperglycaemia after eating. Both obesity and prolonged hyperglycaemia are key factors thought to contribute to the development of diabetes. Obesity itself is one of greatest and growing health issues we face with our domestic felines; it is now estimated to affect 30% of the cat population. We all have a responsibility to reduce this growing health concern and this starts with diet awareness.
Although feeding high carbohydrate and vegetable based diets is not going to cause cats any direct short term harm, it is hardly promoting better health and may well be predisposing them to problems long term. Nonetheless commercially prepared dry diets do provide a convenient way of feeding our cats and beneficially reduce tartar formation and the subsequent development of periodontal disease. Dental disease in cats is another key health problem in the feline population and one of the greatest risk factors of developing problems is feeding commercial wet food. Therefore dry diets should continue to play a role in feeding our feline companions.

CHOOSING THE BEST DIET FOR YOUR CAT

Armed with the knowledge of a cat’s unique biochemistry we can select diets that are more aligned to their physiological needs by being savvy. Assessing food for its ingredients and nutritional break- down, rather than selecting one based on the most appealing cat on the pack, will help your cat’s long term health and wellbeing. So when you’re next in the supermarket or pet store aisle considering what to buy, take the packet off the shelf and compare the backs of packs. Look for diets which have the first ingredient listed as a good animal based protein, ideally from a high meat content dry cat food, and compare the amount of protein, fat and ash. We have focused here on dry diets as an example as they are easier to compare. Wet diets have large amounts of moisture in them which varies between brands and makes comparison more challenging. The take home messages though are still the same, consider the quality of the ingredients and the sources of protein.

There are some great wheat and grain free cat food products available in the market and on on-line that provide great source of protein and also ensure your cat has the essential nutrients they need to be healthy in the long-term.