The Use of Essential Oils in Ruminants as Modifiers of Rumen Microbial Fermentation

87 0. Take Home Message The effi ciency of energy and protein utilization in the rumen may be improved through the manipulation of microbial population. Antibiotic ionophores have been very successful in improving these effi ciencies, but its use in animal feeds is facing reduced social acceptance. For this reason, other alternatives to control specifi c microbial populations are currently being investigated. Some essential oils have antimicrobial activities resulting in reduced peptidolysis, deamination and methanogenesis. Because the effects of essential oils are diet and pH dependent, the selection of the appropriate essential oil will depend on the specifi c objectives and target animal. Moreover, because essential oils may act at different levels in the energy and protein metabolic pathways, their careful selection and combination may provide a useful tool to effectively manipulate rumen microbial fermentation.