AimsTo evaluate natural terpene compounds for antimicrobial activities and determine whether these compounds could be used to control microbial activities and pathogens in production animal facilities. Methods and ResultsThymol, geraniol, glydox, linalool, pine oil, plinol and terpineol were tested in laboratory studies for ability to control the production of odorous volatile fatty acid compounds and reduce pathogen levels in manure slurry preparations. Thymol is a terpene phenolic compound and was most effective for reducing fermentation products and pathogen levels (P<005), followed by the extracts linalool, pine oil and terpineol, which are terpene alcohols. Select compounds thymol, linalool and pine oil were further evaluated in two separate studies by applying the agents to feedlot surfaces in cattle pens. Feedlot surface material (FSM; manure and soil) was collected and analysed for fermentation products, levels of coliforms and total Escherichia coli, and the presence of E.coli O157:H7, Campylobacter, Salmonella, Listeria and L.monocytogenes. The reduction in fermentation products but not pathogens was dependent on the moisture present in the FSM. Treatment with 2000ppm thymol reduced the prevalence of E.coli O157:H7 but not Listeria. In a separate study, treatment with 4000ppm pine oil reduced E.coli O157:H7, Listeria and Campylobacter (P<005). Linalool was tested at two levels (2000 and 4000ppm) and did not affect pathogen levels at either concentration. ConclusionsNatural compounds bearing terpenes can control pathogenic bacteria in treated manures and when applied to the feedlot surface in production cattle systems. Pine oil is a cheaper alternative to thymol and may be a useful treatment for controlling pathogens. Significance and Impact of the StudyThe control of bacterial pathogens in animal productions systems is an important step in preharvest food safety. Waste products, such as pine oil extract, from the pulp wood industry may have application for treating feedlot pens and manures to reduce the pathogen load.