drferox:

Well, make yourself a cup of tea and prepare for a long read, because there are lots of myths about nutrition. I should start first and foremost by saying that I am not going to tell anyone what to feed their cat, or dog, unless that animal is a patient of mine. I’m only going to tell you what to consider.

The first one is that lots and lots of laypeople sites will say ‘meat should be the first ingredient’ often followed by ‘no nasty byproducts’ and this is not strictly the case. Cat food must have meat in it, but it doesn’t strictly have to be the first ingredient, especially if it uses multiple meat sources.

What I want to know about any given wet cat food is this:

• Is it a ‘guaranteed analysis’ or a ‘typical analysis’. A guaranteed analysis is superior.
• How much of it is water, indicated by ‘Moisture percentage’
• How much is protein, and is that figure ‘as fed’ or ‘as dry matter’.
• How much is fat, and is that figure ‘as fed’ or ‘as dry matter’.

Macro and micronutrients are also important, especially taurine and in growing cats, but that information is often unreasonably difficult to find outside of the premium diets.

This is a large part of the reason, incidentally, that vets and a profession often recommend a couple of brands over other. Getting all the information I require to confidently recommend a diet is easy for Hills, Royal Canin, Advance, etc but nearly impossible without phoning and begging any of the supermarket brands. Honestly, if a brand of food wants me to be able to honestly recommend it, it needs to provide its nutritional information in an easily accessible manner. Otherwise you have to go to the store to start getting any nutritional info, as I did.

Yeah, I went to the supermarket and started snapping pics of all the nutritional information available on the labels of various wet food brands and looked like a crazy lady doing so. Here are the unedited label photos, on another post for neatness.

Some points to note:

• Some brands have a guaranteed analysis, which is more reliable and suggests better quality than a typical analysis
• Some packets will clearly state they are compliant with AAFCO (
  The Association of American Feed Control) recommendations, even here in Australia.
• Then others, like Smitten, will subtly say ‘Complementary food only’, which means you cannot guarantee or expect a cat fed that food alone to remain healthy for a year. It’s not well marked.
• Only one of them offered any indication of the Moisture Content, which is what you need to make sure you’re comparing apples with apples.

The moisture content is important, because if you look at those labels as-is you will see all of these diets only offer 9% to 13% protein. For a species that requires a high protein diet, that doesn’t sound like a whole lot, but that’s because you’re not taking the water into account.

To simplify, it’s not unreasonable to consider food as being made up of only four things: protein, fat, carbohydrates or water.

All of these diets list their fat and protein, but only Fancy Feast Originals listed its moisture percentage, and once you know the percentage of three components, you can use simple maths to figure out the fourth. Fancy Feast isn’t the most expensive, nor is it the cheapest, it’s middle of the range.

But why are there always carbohydrates in my cat food? Because there’s always carbohydrates in meat. Glycogen is the most common, it’s the energy storage molecule in muscle and liver that makes it taste good, and incidentally the cat uses the same enzymes to digest it as they do starch. This is probably why they often like starchy things. Cats can and do digest carbohydrates, beware of any source that claims they do not.

So out of the canned foods at my supermarket, you’d think they all sound pretty similar with their protein ranging from 9-13% and their fat from 1.5-5.5%. But you have no way to compare them without knowing the moisture content.

If one diet is 9% protein, 2% fat and 80% moisture, then it’s 9% carbohydrate. If it’s 9% protein, 2% fat and 70% moisture, then it’s 19% carbohydrate.

Unfortunately, finding the moisture content of many of these diets is difficult. However, it’s not unreasonable to assume that cheap wet food contains a higher moisture content, as it’s usually the case. Water is cheap.

If you can get the moisture content, you can calculate the percentage of fat/protein or carbohydrate as a Dry Matter Percentage (what’s left after removing the water). It’s simply the nutrient % / (100- moisture %)

For a normal cat, we’re looking for a protein level that’s at least 25-35% of the dry matter, and fat that’s 10-30% of the dry matter, depending on its digestibility.

For reference, the Fancy Feast Originals can in this sample had 55% protein and 10% fat by dry matter, which is more than the minimum amount of protein, but that’s perfectly alright for a normal cat.

If you compare that to the ‘Gourmet Delight’ Natural Grain Free diet, you have to guess the moisture percentage. If you guess moisture at 80%, then by dry matter you have 45% protein  7.5% fat and more carbohydrates than the Fancy Feast had. If you guess only 70% moisture, and most canned foods are between 70-80%, then those numbers start to look even worse.

The fancy ‘Natural’ and ‘Grain free’ means absolutely nothing for the cats.

(The ‘natural, grain free’ dies even specifies ‘no nasty byproducts’ on the tin and the website is full of dumbed-down myths to sell you your food. Also check out the people listed as answering their FAQs, I can’t even tell whether they’re vets or not. No ‘Dr’ or qualification, and not easy to Google.)

You would think cheap cat food is going to be poorer quality than expensive cat food, but especially in the case of the Grain Free trend, it’s not always the case. This is because if something is more expensive, it is often perceived as better by consumers, even if it is really not, so the manufacturer can hike the price up a bit freely

So after you’ve decided whether the diet has enough protein, enough fat, and meets suitable nutritional guidelines like
AAFCO, then you look at what the ingredients actually are. Most meats are going to be around 90% digestible and usable by the cats, while vegetable proteins are only 40-50% useful at all. So if the diet has a lot of high protein vegetables, that protein percentage may be artificially elevated and not utilized well by the cat’s metabolism.

I’m not going to talk about grain free versus not, because the vast majority of the time it makes no difference to the cat and is simply a personal choice on the part of the human feeding it.

Lastly, look at how much you need to feed to maintain a body weight. If the food doesn’t tell you the moisture percentage, and doesn’t tell you the calorie content, it should at the very least have a feeding guide. If you need to feed twice as many packets of one food to maintain weight as another, then it’s probably either lower quality, higher fiber or higher moisture than another.

That said, you might want a lower calorie food or a higher moisture food to help a cat feel full while losing weight, or to improve stool quality. That’s ok, pick something that suits your purpose.

With me all the way to the end? Well done. Crack out a biscuit to have with your tea.

TL:DR:

• You wont find all the nutritional info you need on the packet
• Check the protein and fat levels
• Check whether it’s a complete diet, (eg
  AAFCO

  standard) or a ‘Complementary food’

• Make sure it’s got meat/fish

And this rather long post is the simplest I can make cat wet food for you.

(Oh, and if you have something to add to the conversation, please do so in a reply or reblog. Random anecdotes sent to the ask box will not be published to keep the topic all in one place)