Everything You Need to Know about Cat Food and Protein

April 03, 2015
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Informed owners know that protein is a vital part of their cat’s diet, but a greater understanding of protein is necessary to make good decisions about what to feed your cat.

Protein plays many roles in a cat’s body. It is essential to making and maintaining muscle, hair, and other anatomical structures. Parts of the immune system (e.g., antibodies) also contain large amounts of protein, and unlike many other animals, cats use protein as their primary energy source.

Cats need to eat a lot of protein to meet all these needs, but the protein that cats take in doesn’t directly get incorporated into their bodies. First, the digestive system breaks down dietary proteins into amino acids that can be absorbed and then reassembled into the specific types of proteins that the cat needs at that time.

All protein is made from only 23 different amino acids. A cat’s own body is able to make 12 amino acids from simpler building blocks. These 12 amino acids are called non-essential amino acids since they don’t specifically need to be present in a cat’s diet.

However, cats cannot make the other 11 amino acids necessary for producing all the proteins their bodies need. These are called essential amino acids. Arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine, and taurine are essential amino acids for cats.

A lack of any essential amino acid in the diet will eventually lead to health problems. For example, arginine deficiency causes toxic levels of ammonia to build up in the body, resulting in vomiting, muscle spasms, seizures, coma, and death. A shortage of taurine induces cardiomyopathy (a serious form of heart disease) and central retinal degeneration and blindness.

How can owners determine if a food provides enough protein in general and, more specifically, all 11 essential amino acids that cats should be eating?

First, foods that display an AAFCO (Association of American Feed Control Officials) statement of “nutritional adequacy” (also known as a “complete and balanced” statement) contain at least the minimum amount of protein and essential amino acids that cats require. Ensuring that any food you offer has an appropriate AAFCO statement (e.g., growth and reproduction, adult maintenance, or all life stages) on its label is a good place to start.

Next, take a look at the food’s guaranteed analysis. The minimum protein percentage will be listed. If you have seen numbers close to the AAFCO minimums (26% for adult maintenance and 30% for growth and reproduction), the manufacturer is not providing more than the bare minimum cats need to survive.

Given a range of foods to pick from, cats seem to naturally gravitate towards eating a diet that provides approximately 50% of its energy from protein. High-quality canned foods more closely match this dietary preference than do dry, but if you offer cats both, they will pick and choose to meet their needs.

Now study the food’s ingredient list. Animal-based protein sources (e.g., egg, meat, dairy, and fish) contain more essential amino acids than do plant-based protein sources (e.g., soybeans or corn gluten meal). Products that rely on plants to provide most of their protein cannot provide all the essential amino acids cats need without supplementation even if the food appears to be “high protein” based on its guaranteed analysis. Select a cat food that includes meat, fish, or meat and fish meals at the top of the ingredient list.

Finally, feed your cat the food you’ve picked for at least a month. If you’ve followed these guidelines and your cats are thriving, you can be confident in your choice.

Dr. Jennifer Coates

Image: April Turner / Shutterstock