AbstractGroups of 16 pregnant rats per treatment were fed ad libitum a basal diet containing 0, 0.3, 0.5, or 0.7% mimosine or allowed a restricted intake of the diet with no mimosine until killed on day 20 of gestation.Incremental increases of mimosine caused significant (P<0.01) decreases in daily feed consumption, weight gain per unit of food, and total weight gain. A significant (P<0.01) increase in fetal resorption, but no difference in mean conceptuses per litter, was associated with 0.7% mimosine. Fetal deformities due to constriction of localized parts occurred in litters from females fed 0.5 and 0.7% mimosine. Deformities were associated with perforations in the uterus between placental attachments with partial protrusion of fetuses through the uterus.Most sacral vertebrae were missing in fetuses of females fed 0.7% mimosine and of restricted intake controls. There were no differences in hematocrit values due to treatment.