This study demonstrated that essential oil fogging
improves hygiene standards in broiler houses. The use
of essential oils before stocking reduced bacterial counts
in the air and on wall and drinker surfaces in experimental
rooms and reduced the populations of mannitolpositive
staphylococci in the room treated with peppermint
oil solution. Oil treatment had no significant
effect on litter hygiene (Tables 1 to 3). During broiler
rearing, the mean total counts of mesophilic bacteria,
Enterobacteriaceae, and staphylococci were also highest
in the control group (Tables 4 to 6). A single exception
was noted in litter where the average Enterobacteriaceae
concentrations in the room treated with
peppermint oil were higher than in the control. Bacterial
contamination levels were reduced by both oils,
but thyme oil demonstrated a stronger antibacterial
effect with regard to coliform bacteria. Peppermint oil
proved to be a more potent inhibitor of staphylococci
(Table 6). Hammer et al. (1999) performed an in vitro
study investigating the activity of 52 plant oils and
extracts against various bacteria, including Salmonella
Typhimurium, E. coli, Klebsiella pneumoniae, Serratia
marcescens, and Staphylococcus aureus, and thyme oil
was characterized by the lowest minimum inhibitory
concentrations against E. coli. The results of the cited
study demonstrate that thyme oil is a more effective
inhibitor of the above bacteria, excluding Salmonella
Typhimurium, than peppermint oil.