Pet food manufacturers present the ingredients of cat food in the best possible light, which is understandable.
The manufacturers are regulated as to the information that must be listed on the packet. Under the rules, manufacturers must list some basic nutrient percentages on the packaging.
Manufacturers “manipulate” the rules. These are the tricks of pet food labelling. Customers are generally unaware of this. It is helpful to be able to read ingredient lists so that comparisons between different cat food products can be made. This is particularly important when comparing dry and wet cat food.
The mouse is 40% protein, 50% fat, 3% carbohydrates2
To compare wet and dry cat food you have to eliminate the water content from both. You can then compare what is left, namely, the active ingredients. Dry cat food does contain some water, which is called “moisture”. About 10% of a dry cat food pellet is moisture. Wet cat foods have about 75% moisture.
Calculation for dry-matter basis comparison
Let’s say you’re looking at a packet of dry can food and a box of wet cat food. The protein content on both is listed at 15%. That does not mean that there is the same amount of protein in each product.
To make a comparison on a dry-matter basis, you do the following:
- Wet cat food: divide the figure of 15% by 0.25 which is 25% in decimals. You do this because there is 75% moisture in wet cat food (100%-75% = 25%). The resulting figure is 60%
- Dry cat food: divide the figure of 15% by 0.9, which is 90% in decimals. You do this because there is 10% moisture in dry cat food (100%-90% = 10%). The resulting figure is 16.7%
You can see that the amount of protein in dry cat food (in this example) is much lower even though the percentage content is the same on both labels.
Putting mathematics to one side for a minute, the reason is that the ingredient percentage for dry cat food is not far from a dry-matter basis presentation. So, if the list says 15% protein that is not far from the true figure on a dry-matter basis. Whereas for canned or pouched food the listed figure will be much lower than in reality because a lot of the food is water, which you have to eliminate from the calculation.
Translating the Name of the Cat Food
Yes, it seems there is a hidden message in the name of the cat food. Under the rules of pet food labelling….
“Beef Cat Food” means the food has to be almost all beef (95% beef on dry-matter basis). Confusingly (for me), if the food is called, “Beef Entree” or “Beef Feast” it need have only 25% beef in it. If the word “dinner” is in the name it should contain 25% on dry-matter basis of the ingredient in the name (i.e. Beef Dinner for Cats). This is the “dinner rule”!
At the bottom of the quality ladder, when the word “with” is employed in the name, such as “Cat Food with Beef”, the beef content need only be 3%. Of course, the same applies any other main ingredients such as chicken or lamb etc.. Many cat food products labelled as meat of a certain kind will have other meat proteins such as fish.
As expected, ingredients have to be listed in order of decreasing content levels. This rule can be manipulated by the manufacturers. The manufacturer wants to put the best ingredient at the top to give the impression that the food is full of wholesome meat protein.
If the product contains corn, this ingredient can be divided up into three ingredients (corn grits, corn flour, corn gluten). Each of these three corn ingredients will have a lower percentage content that if grouped together. When grouped together, the corn content may be higher than the meat content but divided up each element falls down the list. This enhances the list, which makes the food more marketable. Apparently, this ploy is frequently used when listing cereals in pet food.
Another trick concerns chicken content on dry cat food. Chicken has a high moisture content. Chicken dehydrated when used in making dry cat food. It is then called “chicken meal”. However, manufacturers are allowed to include the moist weight (the weight before reduced to chicken meal) when listing it as an ingredient on the label. This ensures that it is at the top, where manufacturers obviously want it. They don’t want “corn flour” to be the major ingredient, which may well be the case.
Apparently, in the USA (2007), carbohydrate content need not be listed under the rules. Carbohydrate content is important. Dr Hodgkins DVM provides an example as to how it can be worked out:
This is a typical listing for canned cat food:
- Crude protein Min. 9.5%
- Crude fat Min. 5.0%
- Crude fiber Max. 0.8%
- Moisture Max. 75%
- Ash (minerals) Max. 2.0%
The ingredients listed from protein to ash are added up ignoring other ingredients listed. The total for the above is 92.3%. That figure subtracted from 100% makes 7.7% which is the amount of carbohydrates in the food on a wet basis.
On a dry-matter basis the figure rises to 31% (7.7 divided by .25). This is a very high carbohydrate content. An 8% carbohydrate content on a dry-matter basis for wet cat food is much more desirable.
“For All Stages of Life”
This is a phrase used on labels. If it is used the product must have the extra protein and carbohydrates to feed and support young kittens and adults2.
Notes on Regulation
The American pet food industry is unregulated in practice1, although there are regulatory bodies:
- FDA (Food and Drug Administration) – due to a lack of resources because of budgetary constraints the FDA exercises little oversight of the pet food business.
- AAFCO (Association of American Feed Control Officials)- this organisation prioritises human health safety concerns in ensuring the safety of feed for livestock used to feed people leaving little funding and resources to test pet food to make sure it reflects what is on the label. Look for “complete and balanced” on label2.
- PFI (Pet Food Institute) – this organisation works on behalf of the pet food manufacturers. It is better funded than the FDA and AAFCO. It lobbies politicians to ensure that laws are not passed that would better regulate the manufacturers and the products they produce. Without wishing to be cynical, the pet food industry is another example of how a country is run by big business and not the people through elected politicians.
- The FDA has established very specific guidelines for pet food labelling, but the required labels do not contain enough information for you to figure out the exact nutrient content because (a) you have to convert to dy-basis matter and (b) they quality of the original ingredients are not mentioned2.
- Your Cat by Elizabeth M Hodgkins DVM (unless otherwise stated)
- Cat Owner’s Home Veterinary Handbook
Associated pages: Search results for “cat food” on PoC.