EFFECT OF FINISHING DIETS ON ESCHERICHIA COLI NUMBERS, AND PREVALENCE OF ENTEROHAEMORRHAGIC E. COLI VIRULENCE GENES IN THE FAECES OF CATTLE

摘要

Previous investigations have shown that the formulation of finishing diets may affect the shedding of Escherichia coli in cattle faeces (McSweeney et al. 2002). An animal study was conducted to examine the effect of dietary inclusion of molasses (simple sugars), grain (starch) and roughage (structural carbohydrate) on the shedding in cattle faeces of E. coli and enterohaemorrhagic E. coli (EHEC) virulence factors [shiga toxin genes, stx1 and stx2; accessory virulence factors, intimin (eaeA) and plasmid-encoded enterohemolysin (hlyA)]. Thirty Brahman-cross steers (329 kg mean weight ± 3.2 kg sem) were initially fed a high grain (80%) diet. The cattle were then allocated to 3 groups and fed ad libitum either (1) 50% molasses, 28% Rhodes grass (Chloris gayana) hay, 15.0% whole cotton seed, 4.5% cotton seed meal, 1.5% urea and 1% mineral/vitamin premix (M+R), 2) 80% sorghum, 5% peanut shells, 5.5% cotton seed meal (G), or 3) Rhodes grass hay plus 20 g urea/kg DM (R).