During the colonic fermentation of endogenous and undigested amino acids, several putrefactive compounds (i.e., ammonia, aliphatic amines, indoles, phenols and volatile sulfur-containing compounds) are produced and are responsible for the malodor of dog and cat feces (Hussein, 1999).
The extracts of the plants Yucca Schidigera and Quillaja saponaria have been studied for years for their use in the feeding of dogs and cats, as well as other species. Main effects studied are the decrease of fecal malodor, reduction of flatulence, reduction of the arthritis prevalence, protozoa control, reinforcement of immunological system, and animal wellness in general.
Some studies have shown good results in other species, like swine. Using quillaja as feed additive for sows, several effects were described, like improvement in fecal texture, 11% more solid (P<0.05), corporal score of sows at end of nursing 12% higher (P<0.05), compared to the control females. Piglets of sows that received supplemented diets presented higher weights on birth (1.2 x 1.4kg) and at weaning (5.5 x 5.9kg) weights, both at P<0.05 (Hauptli, 2006).