It's determined by test dogs who are allowed to choose one formulation compared to another. You can do your own palatability study by putting two brands in bowls side by side to see which your dog prefers. Many manufacturers use poultry or beef digests to enhance the palatability of their foods. For example, poultry digest consists of chicken or turkey parts that have been broken down by using chemicals or enzymes, resulting in a powder or liquid. This is included in the dog food mixture during processing, or sprayed on at the end of the process along with vitamins.
Dogs love the flavor.
For every food reviewed in our magazine, we assign a category. These categories are based primarily on quality of ingredients and the concentration of nutrients in the food. We also take into consideration the Guaranteed Analysis, metabolizable energy, digestibility and price per feeding. In addition, we look at how the foods perform in our own dogs. Although the guidelines we use are for a dry, adult maintenance diet, there is plenty of variation within each category.