27 December 2016

1 minute read

North America

Introduction

In livestock production, antibiotics at sub-therapeutic levels are commonly used to enhance the efficiency of converting feeds to gain (e.g., milk and meat) and/or prevent metabolic disorders and health problems. However, the restriction and the ban (e.g., European Union) on the use of antibiotics in several countries have prompted scientists and the feed industry to search for alternative products. Phytogenics offer a unique opportunity in this regard as many plants produce secondary metabolites, such as essential oils that, when extracted and concentrated, may exert antimicrobial activities against a wide variety of rumen microorganisms. Accordingly, research on the use of essential oils in ruminant nutrition has increased over the last decade. Understandably, most of this research is laboratory based (i.e., in vitro) and has allowed to screen a large number of essential oils and their main constituents for their effects on rumen microbial fermentation. The number of in vivo studies has increased over the last years, but more research work is still required to assess the potential of these phytogenics to enhance feed efficiency (nitrogen and energy) and improve ruminant performance (i.e., milk and meat). This review presents recent developments in use of essential oils as feed additives in ruminant nutrition. Antimicrobial properties, mechanisms of action, effects on ruminal protein metabolism, enteric methane production, animal performance, and challenges are discussed.

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