Psyllium is a bulk-forming laxative which causes the fluid and ion content of the feces to increase by absorbing water. It is used in birds to enhance the elimination of certain substances from the gastrointestinal tract, by reducing the transit time in the intestines. Psyllium can also be combined with water and used as a lavage solution for foreign body removal.
Mukhtar, Nasir, et al. Effect of psyllium husk fiber on growth performance, egg quality traits and lipid profile in layers under high ambient temperature. J. World Poult. Res 7 (2017)