Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: October 7, 1999
Publication Date: N/A
Technical Abstract: Dietary manipulations have been proposed as potential preharvest interventions against bovine EHEC O157 infections. A group of 200 finished feedlot beef cattle naturally-infected at high fecal prevalence with EHEC O157 were randomized into 20 pens of 10 cattle each. All cattle were on a grain- (corn) based finishing ration of about 90% concentrate. On d 0, 10 random pens were switched to 100% alfalfa hay & 10 pens remained on grain. On d 14, cattle were loaded onto commercial cattle trailers, shipped for 2 h, unloaded into 2 clean crowded pens, & held for 16 h with water access but no feed in order to simulate shipping & holding for slaughter. All cattle were tested for fecal EHEC O157 on d 0, 7, 14 (preshipping), & 15 (postshipping). Total coliforms and biotype I E. coli/fecal gram, fecal pH, & body weight were measured at these same times. Fecal EHEC O157 shedding in hay fed cattle was 52% on d 0, 18% on d 7, & 15% on d 15 after simulated shipping. Fecal EHEC O157 prevalence in grain fed cattle was 54% on d 0, 53% on d 7, and 14% on d 15. Fecal pH was about 1 unit higher in hay fed (approx. 7.0) vs grain fed (approx. 6.0) cattle. There was no difference in total coliforms or biotype I E. coli numbers among hay & grain fed cattle. Cattle on grain gained about 1 lb/day; cattle on hay lost about 0.25 lb/day. These results suggest that 1) short-term dietary manipulations may reduce bovine fecal prevalence of EHEC O157 but not without adverse financial consequences & 2) transport & holding of cattle for slaughter may also reduce fecal EHEC O157 shedding.