EVALUATION OF DIETARY INFLUENCES ON ESCHERICHIA COLI O157:H7 SHEDDING BY CATTLE

The effect of diet type and an abrupt change of shedding of Eseherichia coli O157:H7 was investigated, first group of animals were fed a hay which was tow in nutrient and digestible energy and high fiber, the second group mixture of concentrated feed (grains) and barseem which is height 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 O157: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 O157:H7 for 55 days, animals fed on barseem and grains shed it for 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 5^th day post-inoculation were 3x10⁴ and 201x 10⁶ for the first, second and third group respectively, whereas the concentration of the microorganism at the 25^th day post inoculations were 5x18⁸n, 5.8x10¹³ and 6x10¹² respectively. The groups reach the last detectable concentrations (2.2x10⁴, 3.4x10² and 2x10³) at the day (40^th, 50^th and 45^th) post-inoculation for the (first, second and third) group respectively. It can be concluded that the grains and barseem fed animals shed E.coli O157:H7 longer and more concentrated than barseem or hay fed animals.