Dietary Effects on Escherichia coli O157:H7 Shedding in Beef Cattle during Transportation

Introduction: Beef cattle production in Alabama is primarily based on a cow-calf production system;calves produced in Alabama are weaned and shipped to feedlots in the Midwest. During transportation, cattle will be under multiple stresses (such as limited spaces and feed) for up to 3 days, which could lead to body weight loss and Escherichia coli O157 cross-contamination. The dietary effects on stress as well as O157 shedding still need evaluation.

Purpose: The purpose of this study is to assess the effects of two diets, hull-based dry feed (DF) and corn silage based high moisture feed (HM) on body weight and E. coliO157 shedding in cattle during transportation.

Methods: Fifty four cattle were fed a DF diet while another 63 were fed a HM diet for 45 days before transportation. Twenty five DF-fed cattle and 33 HM-fed cattle were loaded on a truck and driven for 24 hours. The concentrations and prevalence of O157 were determined based on fecal samples collected from shipped cattle before (BT), right after (RAT) and 15-days after transport (15AT) and un-shipped cattle (BT and 15AT). The body weight was monitored everyday during the time.

Results: Transportation significantly reduced the cattle the body weight, and increased O157 shedding levels and prevalence regardless the diets. The HM-fed cattle shrink significantly at RAT and could not recover at 15AT. The O157 shedding levels increased at RAT (from 0.63 ± 1.26 to 1.26 ± 1.30 CFU/g feces, P < 0.05) but decreased back to the BT levels after 15 days. Cattle fed the HM diet had lower O157 shedding levels than DF-fed calves at 15AT (P < 0.05).

Significance: Diets play important role on O157 shedding. HM-fed calves had lower O157 shedding levels than DF-fed calves irrespectively of transportation status.