|Ives, S - CACTUS FEEDERS|
|Engler, M - CACTUS FEEDERS|
Submitted to: International Symposium and Workshop on Shiga Toxin ... Escherichia coli
Publication Type: Abstract Only
Publication Acceptance Date: June 30, 2006
Publication Date: October 29, 2006
Citation: Edrington, T.S., Callaway, T.R., Ives, S., Engler, M., Anderson, R.C., Nisbet, D.J. 2006. Artificial lighting extends the duration of fecal shedding of E. coli O157 in feedlot cattle [abstract]. In: Proceedings of the 6th International Symposium on Shiga Toxin (Verocytotoxin)-Producing Escherichia coli Infections, October 29-November 1, 2006, Melbourne, Australia. p. 67. Technical Abstract: Seasonal shedding of E. coli O157 in cattle in the United States is well documented however reasons for this phenomenon are unknown. Fecal prevalence is typically highest in the summer and early fall, decreasing to low or undetectable levels in the winter months. Ambient temperature has been suggested as the most likely factor contributing to these patterns; however we propose a different explanation. We hypothesize that the seasonal shedding patterns are a result of physiological responses within the host animal to changing day-length. Previous research conducted in our laboratory examined the influence of hormones known to respond to changing day-length and the results support our hypothesis. Based on this initial research, an experiment was conducted in a commercial feedlot to examine the effect of artificial lighting on E. coli O157 prevalence. The experiment was conducted in the late summer and early fall when day-length was decreasing and fecal prevalence of E. coli O157 typically decreases. Four pens of cattle received approximately 5 hours of artificial lighting, commencing prior to sunset, daily for 60 days and four pens served as unlighted controls. Freshly voided fecal samples (representing approximately 30% of the steers/pen) were collected from the pen floor and cultured for E. coli O157 after 25 and 53 days of artificial lighting and 28 and 43 days following cessation of the lighting treatment. Fecal prevalence of E. coli O157 remained constant in the lighted pens whereas a decrease (P < 0.01) was observed in the control treatment after 53 days of lighting. Forty-three days following cessation of the lighting treatment, prevalence decreased in the lighted treatment to levels comparable (P > 0.20) to control levels. Understanding the mechanisms underlying the seasonality of this pathogen will enable the implementation of effective control strategies when it is most prevalent.