Beak and mouthparts merely pick up feed particles and force them down throat. Esophagus is a tube connecting mouth to following organs. No peristalsis or fluid secretions occur. The crop provides temporary feed storage. Neutral pH can allow fungal growth.
True digestion begins here.
Oval, muscular organ that has a thick cornified lining. Gizzard of turkey can crush a walnut. Grit is not necessary. Coarse particles are retained for additional grinding. Fine particles pass through.