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This Article Full Text Full Text (PDF) All Versions of this Article: jas.2006-410v1 85/4/1102    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Looper, M. L. Articles by Rosenkrans, C. F. Search for Related Content PubMed PubMed Citation Articles by Looper, M. L. Articles by Rosenkrans, C. F., Jr.

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^1,2

M. L. Looper^*,3, T. S. Edrington, R. Flores, J. M. Burke^*, T. R. Callaway, G. E. Aiken, F. N. Schrick^|| and C. F. Rosenkrans, Jr.

^* USDA-ARS, Dale Bumpers Small Farms Research Center, Booneville, AR 72927; and USDA-ARS, Southern Plains Agricultural Research Center, College Station, TX 77845; and Department of Animal Science, University of Arkansas, Fayetteville, AR 72701; and USDA-ARS, Forage Animal Production Research Unit, Lexington, KY 40546; and ^|| Department of Animal Science, University of Tennessee, Knoxville 37996

³ Corresponding author: mlooper{at}spa.ars.usda.gov

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.

Key Words: dry matter intake • Escherichia coli O157:H7 • ewe • nonesterified fatty acid • tall fescue