This study was conducted to assess the effects of purple prairie clover (PPC, Dalea purpurea Vent.) on feed intake, nutrient digestibility, fecal shedding of Escherichia coli O157: H7 and blood metabolites of lambs. Three groups of lambs (6 per group)were individually fed green chop alfalfa (Alf), a mixture of Alf and PPC in a ratio of 40:60 (DM basis; Mix) and Mix supplemented with polyethylene glycol (Mix-P) for 45 d. Polyethylene glycol (PEG) was included to neutralize the biological activity of condensed tannins (CT) in PPC. Total-tract digestibility was determined using AIA as an indigestible marker. Blood samples were collected to measure serum metabolites and activity of antioxidant enzymes. All lambs were orally inoculated with a 5-strain mixture of E. coli O157:H7 after determination of diet digestibility and fecal samples were enumerated for E. coli O157:H7 after 1, 2, 3, 4, 7, 14, 21 and 28 d of inoculation. Feed intake was similar among lambs fed the 3 diets. The OM digestibility of Mix (P < 0.05) and CP digestibility of both Mix and Mix-P (P < 0.01) were lower than Alf. However, the 3 diets had similar NDF digestibility. After inoculation, lambs fed Mix shed less E. coli O157:H7 than lambs fed Alf between d 1 and d 7 (P < 0.05 to 0.006), and lambs fed Mix-P between d 1 and d 3 (P < 0.05 to 0.012). Lambs fed Alf shed more E .coli O157:H7 than lambs fed Mix (P < 0.001) or Mix-P (P < 0.01) over the 28-d post-challenge period. Lambs fed Mix had lower levels (P < 0.05) of serum creatinine and urea nitrogen than Alf, but both Mix and Mix-P had higher (P < 0.05) levels of serum P. Mix fed lambs had greater (P < 0.05) serum total antioxidant capacity but lower (P < 0.05) serum superoxide dismutase activity than lambs fed Alf. Incorporation of PPC in lamb diets at 60% of DM reduced fecal shedding in lambs challenged with E. coli O157:H7 as compared to Alf. The fact that shedding of E. coli O157:H7 was also reduced with Mix-P suggests that the anti- E. coli O157:H7 response of PPC is not solely due to CT.