4-Ds: Road kill, slaughter house rejects, animals that die on their way to meat packing plants - all are acceptable ingredients for pet food under the "4D" rule. Steroids, growth hormones and chemicals (yes there really is) used to treat cattle including insecticide patches end up mixed into the final product.
Feeding kibble to your pet has almost always some irreversible damage. Kibble dehydrates the system leaving it lacking in moisture which therefore causes kidney and bladder stones/crystals. Pets have to drink over 5 times the amount of water to stay hydrated throughout the day. Kibble also causes periodontal disease from buildup of chemicals, addicting additives and preservatives. Kibble is also loaded with sugar although you won't find that on the label. The bags are almost half sugar of the actual food in the bag.