|Rosenkrans, Jr, Charles|
Submitted to: Western Section of Animal Science Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 4/13/2005
Publication Date: 6/22/2005
Citation: Looper, M.L., Edrington, T.S., Rosenkrans, Jr, 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. 56:213-216. Interpretive Summary: Escherichia coli O157:H7 causes foodborne illness in humans. Data investigating the effects of endophyte-infected tall fescue on E. coli 0157:H7 shedding is non-existent. Sheep experimentally inoculated with E. coli O157:H7 were fed diets containing endophyte-infected (E+) or endophyte-free (E-) tall fescue seed for 7 d. Fecal shedding of E. coli O157:H7 was decreased in E- ewes compared with E+ ewes. This information is of interest to livestock producers, extension personnel, and agricultural professionals who advise producers on livestock and food safety management practices.
Technical Abstract: Escherichia coli O157:H7 is one of the most common agents of foodborne illness in humans and has been isolated from ruminants at all stages of production. Objectives of this experiment 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 (average BW = 45 kg) were blocked by body weight and breed, and fed a diet containing either endophyte-infected (E+) or endophyte-free (E-) tall fescue seed for 7 d. Each diet consisted of 50% (DM basis) tall fescue seed. 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 (0.8 and 1.6 kg/d DMI for E+ and E- ewes, respectively); 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+ (67.3 ng/g creatinine) than E- ewes (5.3 ng/g creatinine). Fecal shedding of E. coli O157:H7 was increased (P < 0.06) in E+ ewes [5.4 cfu/g feces (log10)] compared with E- ewes [4.5 cfu/g feces (log10)]. 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. We conclude that short-term consumption of endophyte-infected tall fescue seed will decrease DMI and subsequent ADG, and may increase 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; specifically, reduced dry matter intake.