RESUMO
The effect of diet type and an abrupt change on shedding of Escherichia coli 0157:H7 was investigated, first group of animals were fed on hay which was low in nutrient and digestible energy and high fiber, the second group mixture of concentrated feed [grains] and barseem which is high in nutrient and digestible energy and low in fiber content, third group fed on barseem moderate in nutrient and digestible energy and moderate in fiber content. After a single oral administration of virulent E. coli 0157:H7 all animals shed E.coli 0157:H7. The number of culture positive animals in specific media increased according to the type of diet and also after abruptly changing of diet the shedding of microorganism increases by variable amount. Cattle fed on hay still shedding E.coli 0157:H7 for 55 days, animals fed on barseem and grains shed it for 52 days but animals fed on barseem only shed it for 44 days whereas control group shed microorganism for 31 days only. The concentrations of microorganism at the 5th day post-inoculation were 3x104, 2.4x 107 and 2.1 x 106 for the first, second and third group respectively, whereas the concentrations of the microorganism at the 25th day post-inoculation were 5x 188 n, 5.8 x 1013 and 6 x 1012 respectively. The groups reach the last detectable concentrations [2.2 x 104, 3.4 x 102 and 2 x 103] at the day [40th, 50th and 45th] post-inoculation for the [first, second and third] group respectively. It can be concluded that the grains and barseem fed animals shed E. coli 0157:H7 longer and more concentrated than barseem or hay fed animals. Animals were feeding on grains and barseem or barseem may increase chance of human infection with E. coli 0157:H7