Evaluation of dietary influences on Escherichia coli O157:H7 shedding by sheep

The effect of diet, an abrupt diet change, and fasting on the shedding of Escherichia coli O157:H7 was investigated with experimentally inoculated sheep as a ruminant model, Sheep were fed a grass hay diet (G), which was low in protein and digestible energy and high in fiber, or a mixture of corn and pelleted alfalfa (C), which was high in protein and digestible energy and low in fiber, After a single oral inoculation of E, coli O157:H7, all the animals shed fecal E, coli O157:H7, However, sheep that were fed G shed the bacterium almost twice as long as, and in larger numbers than, did sheep that were fed C, The number of culture-positive animals increased after the diet was abruptly changed from C to G and decreased with the opposite change (G to C), A 24-h fast did not influence E, coli O157:H7 shedding, Horizontal transmission of infection between animals occurred, Recent shedding of E, coli O157:H7 did not affect recolonization with E, coli O157:H7, The findings presented in this study indicate that preharvest control of diet may reduce the risk of E, coli O157:H7-positive animals entering the food chain.