Poultry by-product meal

Poultry by-product meal (PBM) is a high-protein commodity used as a major component in some pet foods. It is made from grinding clean, rendered parts of poultry carcasses and can contain bones, offal and undeveloped eggs, but only contains feathers that are unavoidable in the processing of the poultry parts. Poultry by-product meal quality and composition can change from one batch to another.

Chicken by-product meal, like poultry by-product, is made of "dry, ground, rendered clean parts of the chicken carcass" according to AAFCO and may contain the same ingredients as poultry by-product. Chicken by-product can vary in quality from batch to batch. Chicken by-product costs less than chicken muscle meat and lacks the digestibility of chicken muscle meat.

...
Wikipedia