I'm sure many of you have looked at the ingredient list on a pet food container. And you probably believe that they are listed from most to least. Well, that's mostly true. However, it's not as clear-cut as most think.
Yes, the ingredients are listed in decreasing amounts, from greatest to smallest. However, these are listed by pre-cooked weight, not by percentage. Why is this an important difference? Because one ingredient may weigh more than another, but have fewer nutrients.
Let's look at chicken as an example. If you see "chicken" on the ingredient list, this is chicken meat (muscle) with some remnants of skin and possibly pieces of bone, but excluding organs. For the most part this would be the same kind of meat you and I would eat. If you see "chicken meal", this is the same tissue but dehydrated and ground into smaller pieces. Look at a chicken breast at home and weigh it. Then imagine that same breast that has had all of the water removed. Muscle tissue is going to be about 70-80% water so when you dehydrate it the ingredient is going to weigh less. What is the main reason for using meat? The protein, though there are other nutrients we also consider.
Following so far? Good. Because now we're going to do math.
Let's assume that a chicken breast weighs 500 grams and the non-water portion is 100% protein (not true, but we're wanting easy math here). If we remove water content of 75% we're left with 125g of protein in that breast. If we grind it up, we now have chicken meal which gives us 125g of protein. If we have three dehydrated breasts we now have 375g of protein. That's three times the protein of a single breast. Simple, right? Well, because the meal weighs less than the breast (375g versus 500g) it will be placed lower on the ingredient list, even though it contains more protein! So if you see "chicken" as the first ingredient on one bag of food and "chicken meal" as the third ingredient on a different brand, you might initially think that food #1 is better. But food #2 may actually have more chicken protein!
Reading the ingredient list is certainly a good thing. But it absolutely does NOT give you all of the information about what is in a food, or even exactly how much of each nutrient is present. Analyzing the nutritional content of pet foods can be very confusing, even for veterinarians.
Next time we'll talk about a statement in the fine-print on a pet food label that most people have never read, yet is quite important.