The Biological Value of Cat Food Ingredients


Every time we write a post about cat foods, we get a handful of people who react with disdain. “My Mr. Boots was fed nothing but cat chow since the day he was born and he lived to the ripe old age of 27!” While these sorts of outliers do exist, it’s important that we recommend the best course of action for all cat guardians, not just for a select few who’ve encountered cats that are particularly adaptable when it comes to food. We’re looking to help cats to thrive, not just to survive. A human could survive on Captain Crunch alone, but it’s unlikely that would make them happy and healthy. The fact is that all cat foods are not created equal. Most commercial foods contain lots of cost-cutting ingredients in order to maximize profits for the companies making them. How do we know that for sure? Science.

The biological value of each ingredient can be measured and given a number on a scale of 0-100 for a given species. A “food” with a feline biological value rating of 0 is something of absolutely no nutritional value to cats while one with a feline biological value of 100 is a food that a cat’s biology can make 100% use of. The big pet food companies are banking on the fact that you are not aware of this. That’s why we’re sharing the information with you now. Not to chastise you or to tell you that you’ve been feeding your feline friends incorrectly - far from it. We want you to know the facts so that, regardless of your budget, you can still choose the best possible options for your cat.

Let’s start with that most important of feline nutrients, protein, as our example. There are lots of different types of protein molecules, but they all exist only in living things. They are one of the building blocks of life on this planet and may indeed turn out to be the FIRST building block on which all life that we know of was subsequently built.

Proteins are made up of chains of amino acids, many of which humans, cats and other animals cannot synthesize. These essential amino acids must be present in the animal’s food in order for them to survive. There are big differences in the amino acids that are present in various proteins. While they are all proteins, their quality is determined by how useful they are to an animal’s biology - their biological value. For cats, chicken eggs represent the highest end of the protein scale scoring a 100. Wheat scores a paltry 50.

Dogs and cats digest animal proteins better than those from plants, but products of low-quality animal origin are poorly digested, including skin, feathers, and connective tissue.
— Linda P. Case, Leighann Daristotle, Michael G. Hayek, Melody Foess Raasch, Canine and Feline Nutrition: A Resource for Companion Animal Professionals, 3rd edition 2010

This quote tells us a lot about pet foods. Most of the big pet food manufacturers include poorly digested proteins near the top of their ingredients lists under names like meat by-products and wheat gluten. Neither of these ingredients is of a high feline biological value, yet they occur in many of the commercial cat foods available today. Why? Because they’re cheap.

As recently as the 1980s, cats were going blind and dying from taurine deficiencies in commercial cat foods. The people in charge of designing those diets had been instructed to replace meat with plant products where possible in order to boost profits. The end result was that the diets lacked taurine, a key amino acid that cats cannot synthesize on their own. Of course, no one realized that fact until the research was done to determine the cause of the problems.

Humans are not very knowledgeable about nutrition in general. We can’t even say for sure whether many foods are good for us or bad for us - just take a look at articles about wine or coffee written over the last ten years. The popular “food pyramid”, a dumbing down of human nutrition to help it make sense to everyone, has since been shown to have missed the mark by a significant margin. If we can’t determine what our own diets should be, how will we ever know enough about a species that has been rarely studied? We have to base their diets entirely on the types of foods that we can observe them eating in the wild. Which brings us back to those ingredients lists.

The pet food companies began to include wheat gluten as a primary ingredient in order to boost the overall protein levels of the foods they were making. Wheat gluten levels have crept up slowly and whole meat levels have dropped. Very few consumers have even noticed. Most consumers are mostly persuaded by the the pictures of human food and happy animals on the packages and never really notice what’s in the actual food behind the label.

Which brings us to our suggestion that the foods you feed your feline friends be made primarily of whole meat ingredients. Yes, a raw “prey” diet would be best, but we know that most of our readers live in the real world of deadlines and budgets and it’s not always an easy feat to pull off. Companies like Darwins are doing a great job making it easier to feed raw, but they’re also in the crosshairs of the establishment.

The big pet food companies companies have been so effective at getting their costs down that well-made cat foods can now seem absolutely pricey in comparison. We know that not everyone can afford to feed the best foods, but we encourage you to feed the best that you can afford. Look at the labels and think about what the feline biological values of some of the main ingredients are. If ingredients fall further down the list, it’s okay to let a few things slide by, especially if you’re on a budget, but those top three to five ingredients should always be whole meats with the highest biological value for cats.