Milk has a biological value of 78 percent. Wheat has a biological value of 60 percent. Wheat gluten has a biological value of 40 percent. Corn has a biological value of 54 percent. Digestibility of food.
Digestibility refers to how much of the food is actually absorbed by the bird's system.
The more food that is actually metabolized, the higher the digestibility. During feeding trials, the birds' feces are collected and analyzed to determine the undigested residues of the food eaten. High digestibility indicates that the nutrients within a given food are readily available to be used by the animal. Consideration is given, too, to the type of bird and the normal digestive processes for that bird. Quality before processing.