Vet’s Klinic Clinical Director and veterinary practitioner, Jenny Philip BVMS MRCVS, knows the importance of giving your cat a science based natural balanced diet, which gives them the nutrients they need to thrive knows first-hand how deficient some commercially prepared cat food brands can be from a nutritional point of view.
Currently 70% of UK cat owners feed a commercially prepared diet to their cat, of which half feed a mix of wet and dry cat food; the other 30% of owners feed table scraps, raw meat based diets or allow their cats to eat live prey.
Raw and live prey animal cat food diets are potentially very biologically appropriate. However, at home prepared diets are notoriously difficult to balance correctly and can be time consuming and inconvenient for most. Worryingly, a recent study in the US found 84% of these home prepared diets are deficient in multiple nutrients.
Even so, some commercially prepared cat food diet recipes 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 of these commercial cat foods to highlight their inadequacies.
For example, take the two best market leading dry cat food brands; the analytical constituents (this is the ingredients in the cat food) 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 is a high carbohydrate content in a cats diet a concern?
Are Cats Carnivore or Omnivore?
Cats do not need a high carbohydrate diet, in fact it goes against their biological makeup
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).
Prey Species – Crude Protein% – Fat% – Ash%
- Mouse – 62 – 11 – 13
- Rat – 63 – 9 – 14
- Small Bird – 62 – 9 – 15
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 dogs or ourselves.
Cats 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 in the wild would 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 massive discrepancy within their diet!
Don’t All Commercial Cat Foods Contain Protein?
Technically, commercially prepared cat food products do contain protein, but not all protein is created equal. 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 we have never witnessed a cat with a desire to stalk vegetables, why does this matter?
Cats Need Animal Protein for Health Reasons.
It matters because, 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, the cat will need to take an artificial supplement to ensure they receive the right level of thee important vitamins and minerals. 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 is your cat’s protein coming from?
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, the carbohydrate content in commercially prepared cat food diets affects digestibility; 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 contain large amounts of carbohydrate, therefore cats have evolved with a reduced ability to process and utilise carbohydrates.