During feeding, efforts are made to avoid damaging the bird's esophagus, which could cause injury or death, although researchers have found evidence of inflammation of the walls of the proventriculus after the first session of force-feeding.[66] There is also indication of inflammation of the esophagus in the later stages of fattening.[67] Several studies have also demonstrated that mortality rates can be significantly elevated during the gavage period.[68][69][70]