Baby Girl (1985-2007)
Feline Nutrition


Feline Nutrition

Feline Nutrition

Fifty years ago, most cats survived on farm-fresh meats, fertile raw eggs, dairy, and produce, free of pesticides, hormones, and antibiotics, and often supplemented by whatever they could hunt and kill.

Then came the rapidly growing pet food industry.

The commercial pet food industry

Throughout the 197Os and 198Os, cats were fed a steady diet based almost entirely on wastes and by-products, including those classified as 4-D (dead, dying, diseased, or disabled, and therefore not fit for human consumption. As time went on, the commercial pet food industry promoted highly cooked foods composed primarily of rendered and rejected meat by-products, low-grade bits of grains, and synthetic vitamins and minerals, supplemented by a mix of chemical additives, preservatives, artificial flavoring, and dyes.

While the introduction of premium cat foods today offers healthier alternatives, even today most cat foods are derived from the same sources, usually cooked at extremely high temperatures which destroy most, if not all, of the living enzymes and most of the nutritional value that might otherwise have been there.

Even today, what passes for protein is often by-products derived from animal sources that have been rejected for human consumption. These sources might include such by-products as feathers, beaks, cartilage, lungs, and other indigestible materials, such as poultry fat made from rejected chicken parts.

Most pet foods also contain by-products of grains such as wheat and corn, which are not easily digested by cats. Wheat middlings, brewers rice, and soybean meal, which make up the bulk of most cat foods, are really bits and pieces of stalks, bran layers, outer coverings, and broken grains that were rejected for human consumption. These ingredients are used as a filler, and to artificially boost the crude protein levels of the food.

Most pet foods still contain rendered fats derived from 4-D sources, requiring harsh preservatives in order to prevent the fats from becoming rancid.

As a result of growing awareness on the part of cat owners, more nutritional choices are being introduced to the market, although even those foods that are marketed as premium cat foods should be carefully examined.

Look for whole wheat, brown rice, and whole turkey, chicken, and salmon, rather than wheat middlings, brewers rice, and meat by-product meal. Seek foods that have been naturally preserved, and which include unheated, naturally derived vitamins, minerals, cofactors, essential fatty acids, and nutrients, replacing those made from cheap, inorganic materials.

In short, learn to read the cat food labels, so that you can make caring choices.

Nutrient groups

By the time your cat begins to show symptoms of poor nutrition or illness, she’s quite a way down the road toward a serious problem, so it’s important to understand the basics of feline nutrition.

There are six basic nutrient groups:

  • Water
  • Protein
  • Fats
  • Carbohydrates
  • Vitamins
  • Minerals

Of these nutrients, only protein, fats, and carbohydrates can supply energy. While water, vitamins, and minerals are essential to the life of your cat, they provide no energy.

Energy needs

While you cat may overeat due to habit or boredom, cats generally eat in order to meet their energy needs. Because of this, your cat’s nutrient levels should be in proper balance so that, when the cat has consumed enough food to meet its energy needs, its other nutritional requirements will have also been met.

Since the energy levels of diets will vary, so too will the nutrient levels, and higher energy formulas have higher nutrient levels than do lower energy brands.

Energy is expressed as units of heat known as calories. One thousand calories equal one kilocalorie, or kcal. Fat is the most efficient energy source, providing 2.25 times more energy than proteins and carbohydrates.

Energy level requirement will vary according to:

  • age
  • activity
  • temperament
  • stress
  • environment

Cats cannot extract all of the available energy from the food they ingest. Some of the nutrients available in the food will not be digested, but lost through the stool. Of the nutrients that are digested and absorbed, some will be lost through the kidneys in the urine. The energy that is left, and used by the body tissues, is the metabolizable energy

Digestible Energy = Gross Energy - Stool
DE = GE - S

Metabolizable Energy = Digestible Energy - Urine
ME = DE = U

Metabolizable energy is the best way to evaluate the energy content of your cat’s diet.


Water is the most important nutrient group. A cat can lose all of its body fat and half of its protein, and still survive; but she is in danger of death if she loses as much as ten percent of her total body water.

Water is necessary in the body as a solvent, for transport of nutrients and waste products, and as a lubricant, so your cat should always have water available.


Proteins are made up of individual building blocks known as amino acids, which are joined together by peptide bonds to form different proteins.

Animals don’t have a specific protein requirement, but they do require specific amino acids. There are about twenty amino acids. Dogs are unable to produce ten of these within its own body, and must include them in its diet, while cats require eleven essential amino acids, with the additional need for taurine.

Taurine is not found in plant proteins, such as corn gluten and soybean meal, but must be obtained through meat or seafood, so it is important that the cat’s diet include high quality animal proteins. Otherwise, it will be necessary to supplement the cat’s diet by adding taurine.

It’s cheaper and more sensible to feed your cat food that already includes sufficient amounts of taurine. Cheaper cat foods, and even some of the premium brands, do not.

Protein quality

The quality of a protein source depends on two things:

  • essential amino acids
  • digestibility

One method that is commonly used to measure the quality of a protein is biological value. The higher the biological value of a protein source, the more useful it is in proving the essential amino acids required by the cat.

Meat has a higher biological value than proteins from plant sources, since meat provides the cat with all of its essential amino acids. Animal proteins are considered to be complete sources of protein for your cat since they provide all of the essential amino acids that your cat needs, as opposed to plant protein, which lack one amino acid or another.

Sources of protein include eggs, chicken, fish, pork, lamb, beef, corn gluten meal, and soybeans. Since these are not equal, you should always check the label of a cat food that you’re considering buying in order to see which protein sources are used in the preparation of that food.

High quality animal proteins are better than plant proteins, and a more nutrient dense and digestible diet means higher nutrient availability, which can be evidenced by small, firm stools, improved skin and coat conditions, and a healthier, more active, pet.

Protein is necessary for structure, function, and energy. If your cat’s diet is properly balanced, she will obtain most of her energy from fats and carbohydrates, leaving protein for use in structure and function.

Protein consumption

The amount of protein that your cat requires depends on her age, activity level, reproductive status, health, and metabolic variations. You might hear that premium cat food is too rich, or too high in protein, but that’s not at all true.

In a balanced diet, nutrient levels are determined by the energy content of the food, and most premium brands are more energy dense than grocery store brands. Protein, and other nutrients, are more concentrated in foods that are energy dense, so pets can eat less of these products in order to meet their energy needs, making the total protein consumption comparable to a typical grocery store brand, minus the waste.

In other words, the cat that is being fed a grocery brand of cat food will need to eat more of the food in order to meet her energy needs than the one that is being fed a quality premium brand.


Fats, which may be referred to as oils or lipids, are a necessary part of your cat’s diet, as they serve the following purposes:

  • provide energy
  • provide essential fatty acids
  • carry fat-soluble vitamins
  • increase palatability
  • provide insulation
  • protect the internal organs
  • serve as a structural component of cellular membranes

The essential fatty acid requirements of dogs and cats differ. Both dogs and cats require linoleic and arachidonic acids, but dogs are able to manufacture arachidonic acid from linoleic acid, while the cat needs to have this included in its diet.

Vegetable oils can provide linoleic acid, but not arachidonic acid, while animal fat contains both, so the cat requires animal fat in its diet.


Dogs and cats do not require carbohydrates, but they are included in their diet as a source of energy as well as fiber. Raw carbohydrates are not tolerated well by either dogs or cats, but cooking during processing increases digestibility and simulates the pre-digested carboydrates that the animal would get in the wild by eating the stomach contents of their prey.

There are two parts to a carbohydrate. The digestible portion includes the sugars and starches that are used for energy, while the nondigestible portion is fiber, providing bulk for proper function of the gastrointestinal tract.

Sources of carbohydrates include corn, rice, grain sorghum, wheat, oats, and barley.


Levels of crude fiber in dry cat food should be between 1.5% and 5% of the animal’s diet. When the levels of crude fiber rise above these levels, the digestibility of fat and protein decreases, and the increased fiber also interferes with the absorption of vitamins and minerals. Anticipated results include increased stool volume, poor conditions of the skin and coat, and even malnutrition if these conditions exist for a long period of time.

For these reasons, it’s best to avoid a high-fiber approach to weight loss in cats; opting instead, for cat foods that decrease caloric density by replacing fat with digestible carbohydrates such as brown rice.

Another significant characteristic of fiber in the cat’s diet is its fermentability, which is determined by the normal bacteria which live in the lower intestines of cats. These bacteria are important because they can digest certain fibers and provide energy to the cells of the intestinal lining, maintaining normal function, such as absorption, along the lining of the lower gut.


There are two basic types of vitamins:

  • water-soluble vitamins, such as B-complex and C
  • fat-soluble vitamins, such as A, D, E, and K.

Vitamins aid in metabolism, helping to produce energy.

Cats and dogs differ in their vitamin requirements. Because they are unable to convert Beta carotene to Vitamin A, cats require a preformed source of Vitamin A that can be found only from animal sources. Cats also require higher levels of Vitamin B.

Both dogs and cats are usually able to produce sufficient levels of Vitamin C, although in some conditions of stress, they might benefit from a dietary source of Vitamin C.

Vitamin deficiencies in cats are usually seen only in cats who are fed generic, bargain brands, of cat food, and sometimes in those who are fed homemade diets. When a balanced diet is available, vitamin supplementation can lead to vitamin excesses that can be harmful to the health of the cat.


Minerals are the most commonly abused nutrient group, as they are not well understood. Not only are the levels of minerals in the diet important, but so is the proper balance. Too much of one might affect the absorption of another, leading to a deficiency of that second mineral, resulting in nutritional disease.

Rather than supplementing a poor diet, for the health of the animal it is far better to switch to a better diet, as quality cat food includes enough minerals in the proper proportions to meet the cat’s nutritional needs.

There are two basic types of minerals:

  • micro (trace) minerals
  • macro (major) minerals

The body requires minerals for good bone structure, proper acid-base balance, and as a part of enzymes and hormones. Calcium, phosphorus, and magnesium are important macro minerals.

Proper bone development and maintenance requires a calcium to phosphorus ratio of O.9:1 to 1.2:1 for cats. Changes in this ratio can result in soft bones or in soft tissue calcification.

Supplementing the cat’s diet with meat can lead to problems, since meat contains twenty to forty times more phosphorus than calcium, risking an imbalance in the calcium:phosphorus ratio. Small quantities of meat, given infrequently, as a treat, shouldn’t lead to problems, however.

Magnesium levels are important in the feline diet, as it has been associated with the formation of crystals in the urine. At one time, more than half the cases of feline lower urinary tract disease was the result of struvite crystals.

For years, “low ash” diets were recommended in order to help prevent this disorder, but this recommendation is often misunderstood, or oversimplified by well-meaning veterinarians. The term “ash” refers to the total mineral content of the cat’s diet, so a low ash diet could be low in calcium and phosphorus, yet still be high in magnesium.

To prevent feline lower urinary tract disease, a diet should contain less than O.1% magnesium.

As recent evidence has shown that urinary pH is more important in preventing feline lower urinary tract disease, the urinary pH should be maintained between 6.O and 6.8.

The basics

A cat’s diet must provide her with the proper nutrients, which is defined as any ingredient that aids in the support of health and life.

I’m in my late fifties, so I can remember when most everyone, except for the very privileged, fed their cats table scraps or whatever brand of cat that was selling at a good price at the local store. When they had pet food, the cats ate the same thing that we fed the dogs, as far as I remember.

At any rate, choosing a cat food then, wouldn’t have been a difficult decision, as there were only a few brands, and most stores would stock only one or two of them, and pet stores were places where you bought pets, not where you bought pet food or accessories.

As I remember it, our family cats seemed healthy and happy enough, but they didn’t live as long as my cats do today, although we had a dog that lived to be more than seventeen years old.

Competition is heavy today, and we have more choices, perhaps, than we’d like to deal with. But the choices that we make for our pets will largely determine whether they are with us for only a few years, or half our lives.

Unless your cat is allergic to soy, wheat, or corn, as many are, you probably won’t notice a difference. The cat that is eating an inferior bargain brand of cat food may very well appear to be as healthy and as happy as the one that is eating a premium brand, at least while she is younger, since the detrimental affects of poor nutrition in a cat are subtle, at least on the way down.

Unless you’re paying very close attention, since cats don’t like to admit to weaknesses or difficulties.

Once you’ve begun meeting your cat’s nutritional needs, you should be able to notice the improvements on the way up, including increased activity levels, brighter eyes, and a better coat.

As you shop for cat food, the choices available to you might seem endless. Many of them will be familiar to you, either because they’ve been around for years or - and perhaps even more likely - because you’ve seen them advertised on television over and over.

You’ll notice that some brands are labeled as “premium” cat food. What does this mean?

Premium cat food

Keys to selecting the right food for your cat are the sources and availability of nutrients. Cat foods vary greatly in the quantity of ingredients, formulas, and nutritional value. Typically, premium cat foods can be judged according to a higher standard in each of these important variables.

Premium cat food that lives up to these standards is more densely packed with nutrients and calories than economy brands. Better ingredients are more easily digested, and will contribute more of what is essential toward the health of your cat.

While habit and boredom play a role, cats generally eat in order to meet their nutritional and energy needs. Your cat will eat as much or as little as she needs in order to meet these needs, so a cat that is fed a good quality premium food will generally eat less of it, and leave less behind in the litter box. Smaller servings are easier to digest, and they will be less likely to put on extra weight.

Not all premium brands are alike, so reading the labels is an important part of selecting the right food for your cat.




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