Submitted to: Western Section of Animal Science Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 4/13/2005
Publication Date: 6/22/2005
Citation: Looper, M.L., Edrington, T.S., Rosenkrans, C.F., Burke, J.M., Flores, R., Callaway, T.R., Aiken, G.E. 2005. Effects of feeding endophyte-infected tall fescue seed to sheep experimentally infected with Escherichia coli O157:H7. Western Section of Animal Science Proceedings. 56:213.
Technical Abstract: Objectives were to determine the effects of short-term exposure to endophyte-infected tall fescue seed on fecal shedding and intestinal concentrations of E. coli O157:H7 in sheep. Twelve ewes were fed a diet containing either 50% (DM basis) endophyte-infected (E+) or endophyte-free (E-) tall fescue seed for 7 d. Ewes were experimentally inoculated with E. coli O157:H7 on d 2 of feeding treatment and fecal shedding of inoculated pathogens was monitored daily. On d 7, ewes were euthanized, tissues and contents sampled from the ileum, cecum, and rectum for quantification and qualification of the challenge strain of E. coli O157:H7, and urine collected to determine ergot alkaloid concentrations. Ewes fed E+ seed had lower (P < 0.05) DMI than E- ewes; consequently, E+ ewes lost 0.3 kg/d and E- ewes gained 0.2 kg/d during the 7 d (P = 0.06). Concentrations of urinary ergot alkaloids were increased (P < 0.0001) in ewes fed E+ than E- ewes. Fecal shedding of E. coli O157:H7 was decreased (P < 0.06) in E- ewes compared with E+ ewes. Population of E. coli O157:H7 in luminal contents from the ileum, cecum, and rectum did not differ (P > 0.10) among treatments. Treatment did not influence (P > 0.10) the occurrence of E. coli O157:H7 in cecal or rectal tissues; however, ileum tissues from E+ ewes tended (P = 0.12) to have an increased incidence of E. coli O157:H7. Short-term consumption of endophyte-infected tall fescue seed decreased DMI and subsequent ADG, and increased fecal shedding of E. coli O157:H7 in sheep. Further research is needed to determine if the observed increase in pathogen shedding is caused by ingestion of endophyte-infected tall fescue or alterations in nutrition.