title: Influence of dietary endophyte (Neotyphodium coenophialum)-infected tall fescue (Festuca arundinacea) seed on fecal shedding of antibiotic resistance-selected Escherichia coli O157:H7 in ewes.
abstract: The objectives were to determine the effects of short-term feeding of a toxic endophyte (Neotyphodium coenophialum)-infected tall fescue seed (Festuca arundinacea, cultivar 'Kentucky 31') on fecal shedding and intestinal concentrations of Escherichia coli O157:H7 and the concentrations of prolactin, cortisol, and NEFA in experimentally inoculated ewes. Twelve ewes (mean BW = 46 +/- 2 kg) were fed a diet containing either high endophyte-infected (HI-E) or low endophyte-infected (LO-E) tall fescue seed for 7 d. Each diet consisted of 50% (as-fed basis) tall fescue seed. Ewes were experimentally inoculated with antibiotic resistance-selected E. coli O157:H7 on d 1 of the feeding treatment, and fecal shedding of inoculated pathogens was monitored daily on d 2 to 6. On d 7, ewes were weighed and euthanized, and tissues and contents were sampled from the ileum, cecum, and rectum for quantitative enumeration of E. coli O157:H7. Urine was collected at euthanization to determine total ergot alkaloid concentrations. Ewes fed HI-E had lower (P < 0.001) DMI than did ewes fed LO-E (0.8 and 1.6 +/- 0.1 kg/d of DMI for HI-E and LO-E ewes, respectively); consequently, there was a tendency (P = 0.06) for HI-E ewes to lose 0.3 +/- 0.4 kg of BW/d and LO-E ewes to gain 0.2 +/- 0.4 kg of BW/d during the 7 d. Urinary ergot alkaloids were increased (P < 0.001) in ewes fed HI-E (47.8 +/- 9.4 ng/mg of creatinine) compared with those fed LO-E (6.2 +/- 9.4 ng/mg of creatinine). Prolactin tended (P = 0.06) to be decreased in ewes fed HI-E (7.2 +/- 7.0 ng/mL) compared with those fed LO-E (27.7 +/- 7.0 ng/mL). Fecal shedding of E. coli O157:H7 tended (P = 0.06) to be increased in HI-E ewes [5.4 cfu (log10)/g of feces] compared with LO-E ewes [4.5 cfu (log10)/g of feces]. The population of E. coli O157:H7 in luminal contents from the ileum, cecum, and rectum did not differ (P > 0.36) between treatments. Treatment did not influence (P = 0.30) the occurrence of E. coli O157:H7 in cecal or rectal tissues; however, ileal tissues from HI-E ewes tended (P = 0.12) to have an increased incidence of E. coli O157:H7. Concentrations of NEFA tended (P = 0.12) to be greater in HI-E ewes than in LO-E ewes, whereas cortisol was similar (P = 0.49) for HI-E and LO-E ewes. We conclude that short-term feeding of HI-E tall fescue seed may alter the concentrations of prolactin and NEFA, and may increase fecal shedding of E. coli O157:H7 in experimentally inoculated ewes.
authors.affiliation: USDA-ARS, Dale Bumpers Small Farms Research Center, Booneville, AR 72927, USA. mlooper@spa.ars.usda.gov
authors.forename: M L
authors.initials: ML
authors.lastname: Looper
authors.forename: T S
authors.initials: TS
authors.lastname: Edrington
authors.forename: R
authors.initials: R
authors.lastname: Flores
authors.forename: J M
authors.initials: JM
authors.lastname: Burke
authors.forename: T R
authors.initials: TR
authors.lastname: Callaway
authors.forename: G E
authors.initials: GE
authors.lastname: Aiken
authors.forename: F N
authors.initials: FN
authors.lastname: Schrick
authors.forename: C F
authors.initials: CF
authors.lastname: Rosenkrans
mesh_terms: D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D004032:Diet / Q000662:veterinary; D019453:Escherichia coli O157 / Q000187:drug effects* / Q000302:isolation & purification / Q000502:physiology*; D005230:Fatty Acids, Nonesterified / Q000097:blood / Q000378:metabolism; D005243:Feces / Q000382:microbiology*; D005260:Female; D031751:Festuca / Q000382:microbiology*; D005506:Food Contamination; D005658:Fungi / Q000502:physiology*; D006854:Hydrocortisone / Q000097:blood / Q000378:metabolism; D011388:Prolactin / Q000097:blood / Q000378:metabolism; D012639:Seeds / Q000382:microbiology*; D012756:Sheep / Q000382:microbiology* / Q000502:physiology
chemical_list: D000900:Anti-Bacterial Agents; D005230:Fatty Acids, Nonesterified; D011388:Prolactin; D006854:Hydrocortisone