There are different kinds of chicken feed available for different breeds, ages and culinary uses of chickens, but not all feeds are created equal. Some contain ingredients that are dangerous, and can actually be harmful to both the livestock that consume it and the humans that consume the livestock.
Steroid hormones are added to some chicken feeds, specifically those fed to chickens that need to grow faster for more mature muscle content before butchering. This helps chicken farmers raise and sell chickens ready for slaughtering faster and with less cost to their operation due to a reduction in feed costs. However, these hormones are still present in chicken meat even after slaughtering and cooking, which means humans are getting this extra dose of steroid hormones too.
Roxarsone is an arsenic-based chemical added to some chicken feeds, designed to fight parasites, increase growth rates and improve the pigmentation in the meat. Roxarsone is harmless on its own, but when it is ingested by a chicken and then ingested by humans, it turns into a malignant form of arsenic. The American Chemical Society reported at the time of publication that an estimated 9 billion broiler chickens a year are fed feed containing roxarsone. Its effects on humans are still unknown.
Melamine, a chemical used to manufacture plastics, is sometimes added to chicken feed unknowingly by way of contaminated wheat products. Any feed that is found to contain melamine is recalled and the poultry that consumed it is not sold for human consumption.
Pesticides are chemicals that help to control insect infestations on agricultural products, such as the grains and seeds that are ingredients of chicken feed. According to SustainableTable.org, at the time of publication approximately 66 percent of America's grain production is used in livestock feed. Pesticide contamination can come in the form of residues on grains in feed or in genetically modified grains that are grown with pesticides as part of their genetic makeups.