A formula for comparing the protein in wet food vs. dry.

[Louise]

I’m working hard to keep my two quite senior cats healthy as long as possible. I wanted to cut down the protein for my older cats, while keeping it higher for the younger ones. Some of you probably already know this formula, but it’s how you compare the protein in wet vs. dry food. I thought I’d pass it along just in case there might be someone who would find it useful,. The one you convert is the wet.

Look on the can for the moisture content and subtract that from 100. Look for the protein percentage and divide that by the remainder. If the food was dry, that result would be approximately the amount of protein in it,

[RPM]

The can or bag gives the protein content so I don’t understand why you want a formula for figuring it out.

Friskies dry indoor – min 30% crude protein
Friskies canned – min 9% crude protein

Interesting, considering I thought the canned contained more actual meat. But that is the protein content of each.

[Louise]

Nope, that’s not correct. You’re comparing apples and oranges. You have to remove the water content of the wet food first to get a true comparison. For instance, Orijen is 42% protein. The Core I feed my youngest cat says 12% That’s what had me calling the vet, because I was concerned that she wasn’t getting enough protein. But, if you remove the water content, Core come in at about 54%. This formula came from my vet, who is a cat specialist. I think I’ll believe her.

[Simkie]

Lots of websites describe why taking the labeled as fed protein value from a wet can and comparing that to the labeled as fed protein value from a dry bag is not an accurate comparison.

You have to convert everything to “dry matter basis” to compare two different types of feed like that.

Here’s a calculator:

http://fnae.org/dmb.html

Here’s a good article about it:

http://vet.osu.edu/vmc/companion/our-services/nutrition-support-service/comparing-pet-foods

[saultgirl]

Check out http://www.catinfo.org/ too.

Just wondering, if you are considering lowering the protein, what are you replacing it with? Replacing it with fat should be ok but I would worry about lowering protein to increase the carbs.

[Simkie]

Good point, saultgirl. Piggybacking on that–I don’t think it’s advised to drop the protein for a senior animal barring a diagnosis of kidney disease?

RPM, Friskies wet is 45% protein on a dry matter basis (which is the measurement that matters and is meaningful.)

[Louise]

Kidneys right on the borderline is the problem, and why I want to reduce protein. For the seniors, I’m switching from Orijen to Acana. That’s going from 42% to 35% protein. I give my seniors wet food as well, but they’re both not real fans of wet and wouldn’t get enough calories if I just fed wet.