Effect of curfew on the microbiology of sheep

Summary

The effect of 12 or 24 hour transport and food and water deprivation - FWD - for 12 and 24 hours prior to transport on the levels of E. coli in the faeces of sheep was investigated.
The presence and numbers of E. coli O157 and Salmonella was also determined.
Faecal samples were collected from each of 10 sheep before any treatment, after 12 or 24 hours FWD, after 12 or 24h transport and then after 24, 48 and 72h recovery after transport.
A total of 680 faecal samples were collected and tested for the numbers of E. coli present and the presence and numbers of E. coli O157 and Salmonella.

E. coli was enumerated in 677 samples as the number of E. coli could not be determined for 3 samples, either because of overgrowth by coliforms or because the count was below the level of detection which was <10 cfu g.>
The mean log10 count of E. coli in the faecal samples was 6.05 cfu/g with counts ranging between log10 1.7 to 8.61 cfu/g. Mean log10 counts of E. coli in the faeces of groups of sheep varied between 4.47 and 7.6 cfu/g throughout the experiment.
The mean log10 count of E. coli in faecal samples of sheep was:5.9 cfu/g before treatment6.05 cfu/g after 12 hours FWD6.15 cfu/g after 24 hours FWD5.76 cfu/g after 12h transport6.33 cfu/g after 24h transport
Then after 24, 48 and 72 hours recovery was 6.35, 6.03 and 5.87 cfu/g respectively.
There appeared to be no consistent trend observed for mean counts of E. coli in the faeces of sheep at different stages of the experiment. 
There were no significant interactions between the mean log10 counts of E. coli in the faeces of sheep regardless of FWD or transport times.
It appears the counts of E. coli sometimes fluctuate after FWD or transport but not in a consistent way.
E. coli O157 and Salmonella were not detected in this study and no conclusions can be offered about the effect of FWD and transport on these pathogens.
This does suggest if there were very low numbers present they were not amplified by these potentially stressful activities.
Testing for Shiga toxin genes - stx - in the faeces of sheep was performed to ascertain if there was any effect of FWD and transport times on the presence of these genes. Shiga toxins are predominantly harboured by E. coli and even though the total numbers of E. coli may not have varied significantly between treatments, the type of genes the E. coli possess may have been affected.
The faecal samples collected from sheep were tested for both types of stx - stx1 and stx2. There were no significant differences observed in the prevalence of these genes between different FWD and transport treatments.
In general, there was a decline in the prevalence of stx in the faeces of sheep after FWD and transport, but this difference was not significant. No interactions between FWD or transport treatments were observed.
In conclusion, there appears to be no significant effect of 12 or 24 hours FWD or transport for 12 or 24 hours on the levels of E. coli found in the faeces of sheep. This suggests that applying these FWD and transport times will have little impact on the presence of E. coli and Salmonella in sheep faeces, and subsequently the risk of contamination of carcases.