Plant based protein is anything that comes from a plant ... rice, wheat, corn, barley, tapioca, sweet potato, flax, etc. etc.
Here is the ingredient list for ProPlan Adult Chicken and Rice (I don't know if this is the exact formula you are feeding, I just took the "basic" one).
Chicken, brewers rice, whole grain wheat, poultry by-product meal (natural source of glucosamine), corn gluten meal, whole grain corn, animal fat preserved with mixed-tocopherols (form of Vitamin E), corn bran, fish meal (natural source of glucosamine), animal digest, dried egg product, calcium phosphate, salt, potassium chloride, calcium carbonate, Vitamin E supplement, choline chloride, zinc sulfate, ferrous sulfate, L-ascorbyl-2-polyphosphate (source of Vitamin C), manganese sulfate, niacin, Vitamin A supplement, calcium pantothenate, thiamine mononitrate, copper sulfate, riboflavin supplement, Vitamin B-12 supplement, pyridoxine hydrochloride, garlic oil, folic acid, Vitamin D-3 supplement, calcium iodate, biotin, menadione sodium bisulfite complex (source of Vitamin K activity), sodium selenite.
When reading an ingredient list, things are listed based on weight. The first item on the list is the item that makes up most of the mass of the food on an AS FED basis. So when looking at this ingredient list, the first item is "chicken". Good, right? Not really. Remember that the weight is taken "as fed", so that means BEFORE the moisture is removed. If a whole meat is listed, that means that the moisture content of the ingredient is counted in the weight of the item. So "chicken" is whole chicken, meat and moisture. When all moisture is removed (as it is in the process of making kibble) the actual amount of meat decreases dramatically. Keep in mind that meat is roughly 70% moisture. So while 1lb of "chicken" may seem like a lot, once the moisture is removed, it is really just 4.8oz of real chicken. So looking at the ProPlan ingredient list, when taking away the moisture of the chicken, that ingredient would more accurately appear further down the list behind brewer's rice and wheat. So in reality, the main ingredient of that food is rice and wheat, followed by chicken and then chicken by-products (rule of thumb, avoid all by-products in dog food, they are the garbage bits "beaks and feet" rejected by human food production). Listing a whole meat so that it appears closer to the top of the list is a tricky little scheme that manufacturers use to make their food look better than it is.
What you want to see is the first ingredient being a "meal" (chicken meal, lamb meal, beef meal, etc.). "Meal" means that all the moisture has been removed, so the weight of the ingredient is accurate to the amount of "meat", not the amount of meat + water. Ideally, there should be 3 identified meat products in the first 5 ingredients, with the first ingredient being a "meal". "Identified" meat products means that you know what species it came from. Avoid "fish meal" or "meat meal" or "poultry meal". Instead go for specifics like "salmon meal" or "lamb meal" or "chicken meal". See the difference?
More nastiness found in the ProPlan ingredient list ...
- "poultry by-product meal" ... the rejected pieces of unspecified bird species
- corn ... corn = bad
- animal digest ... again, an unspecified protein source. This could be anything from beef to road kill to euthanized shelter animals. Technically, they are all "animals". And digest is just nasty stuff. They take whatever bits of random animal they happen to purchase and then expose it to high acidity so that it essentially breaks down into a gooey slop.
- animal fat ... again, unspecified source
- fish meal ... unspecified
- salt ... purely for flavor to increase palatability. Unnecessary.
- menadione sodium bisulfite ... proven to promote/cause cancer
) here are the primary ingredients of the basic adult Orijen:
