Experiments were done to determine if stunting syndrome (SS) could be consistently induced in poults, to document physical and physiological changes associated with the induced SS, and to determine whether feeding diets of different ingredient composition to inoculated poults could alleviate the effects of SS. One-day-old poults were dosed per os with tryptose phosphate broth (NonInoc) or inoculum (Inoc). The inoculum was prepared using intestines obtained from a commercial flock of poults diagnosed to have SS. Subsequently, intestines of Inoc poults from a previous experiment were used. Inoculation depressed (P <.01) gain and feed consumption, and impaired (P <.01) feed efficiency in poults fed a corn-soy (CS) diet. The intestinal suspension per se was not responsible for the adverse effects of the inoculum since poults dosed with a suspension prepared from intestines of healthy poults performed as well as NonInoc poults. Pair feeding NonInoc poults showed that only 54% of the depression in weight gain caused by inoculation was due to reduced feed intake. Inoc poults retained less (P <.05) dry matter, fat, protein, and ash from 8 to 9 days of age than NonInoc poults. The jejunal mucosa in Inoc poults was thin and exhibited extensive erosion of villi tips. Activities of disaccharidases were less (P <.05) in Inoc poults than in NonInoc poults. Inoculation had no effect on activities of pancreatic enzymes. Inoc poults fed an animal-protein (AP) diet were able to overcome, in part, the adverse effects of SS observed in CS-fed poults. The mechanism(s) by which the AP diet exerted its beneficial effect was not related to digestion and(or) absorption given that retention of dry matter was less (P <.01) in AP-fed Inoc poults as compared with CS-fed NonInoc and Inoc poults. AP-fed Inoc poults gained more dry matter, protein, and ash than CS-fed Inoc poults, but poults in both treatments lost similar amounts of body fat. It seems that SS was exerting its adverse effect in part by altering energy metabolism. AP-fed Inoc poults were able to convert retained feed into tissue gain more efficiently. No beneficial effects were observed when other diets containing different major protein sources were fed to Inoc poults. When the jejunal mucosa was observed by using electron microscopy, villi tips of Inoc poults were heavily parasitized by long segmented filamentous organisms. These organisms were not observed in the mucosa of NonInoc poults.