Crude Protein is actually a chemical analysis of the food whereby the amount of nitrogen present is used to estimate the amount of protein.
While nitrogen does come from animal protein, it also comes from non-animal proteins like grains, as well as other non-protein nitrogen (NPN) sources. This obviously creates a false impression. You may think you are feeding a food with a higher percentage of animal protein than there actually is.
In addition, many dry food manufacturers include within “crude protein”, protein from carcasses and other waste from slaughtered animals. The word “meal” on a pet food bag may indicate the inclusion of such ingredients, along with meat not fit for human consumption. Unfortunately, inferior ‘meals’ can make a mediocre dog food high in protein — but not high in quality protein!
Crude fat is an estimate of the lipid content of food and its levels are determined through extraction with ether. It includes all the fat in the diet, from both plant and animal sources, with not all types of fat being equally digestible.
There are some pretty healthy sources of both animal and plant fat to choose from - fish oil, beef fat, chicken fat, flaxseed oil or olive oil for example. Problem is, when one checks the ingredients, one more often than not finds only ‘animal fats’ listed.
Animal fat is a by-product of rendering, the same high temperature process that’s also used to make meat meal. The problem with generic animal fat is that it can come from almost anywhere and any species. As a result, a chicken-only marked product may very well include substantial amounts of pork or beef fats.
Crude fiber is the organic residue that remains after plant material is treated with dilute acidic and alkaline solvents and after mineral components have been extracted
The term “fiber” (or “roughage”) applies to complex carbohydrates resistant to mammalian digestive enzymes, although certain bacteria possess the enzymes needed to break them down.
While some food manufacturers use whole grains and vegetables to serve as both a source of nutrients and fiber, many others use dedicated fiber sources such as beet pulp, peanut shells, oats and other brans, tomato pomace, buckwheat and other grain hulls, psyllium, fruit pectin, guar gum or other gums and powdered cellulose.
This last is defined as “purified, mechanically disintegrated cellulose from fibrous plant materials”. Some people call that “sawdust,” which I believe is a fair … see more under ‘ingredients’.
Crude ash is the incombustible inorganic residue remaining after incineration - generally the mineral content of the food.
In pet food the constituents are broken down into several components: carbohydrate, moisture, protein, fiber and fat/oil. It is called ash because when the food is burned (to determine its ash content) carbohydrate, fiber, fat and protein are all incinerated. Ash is the part of the food that remains after incineration.
Moisture is the water content of a pet food, as expressed in a percentage. Dry kibble tends to have a moisture content of between 6 and 10 percent, semi-moist foods between 15 and 30 percent, and wet foods around 75 percent.
As a rule, the higher the moisture content, the better for digestion. Also, the more difficult to preserve. Manufacturers shy away from the semi moist option due to manufacturing difficulties and cost.