Abstract #T171

Section: Food Safety
Session: Food Safety
Format: Poster
Day/Time: Tuesday 7:30 AM–9:30 AM
Location: Gatlin Ballroom
# T171
Effects of purple prairie clover (Dalea purpurea Vent.) on feed intake, nutrient digestibility and fecal shedding of Escherichia coli O157: H7 in lambs.
Qianqian Huang1,2, Long Jin1, Zhong Xu1, Ruth Barbieri1, Surya Acharya1, Tianming Hu2, Tim McAllister1, Kim Stanford3, Yuxi Wang*1, 1Lethbridge Research Centre, Agriculture and Agri-Food Canada, Lethbridge, AB, Canada, 2College of Animal Science and Technology, Northwest A&F University, China, 3Alberta Agriculture and Rural Development, Lethbridge Agriculture Centre, Lethbridge, AB, Canada.

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.

Key Words: purple prairie clover, E. coli O157: H7, condensed tannins