Evaluation of the Potential Use of Plant-derived Essential Oils in Ruminant Nutrition

Recently, there has been a renewed interest in using plant extracts as feed additives in ruminant nutrition. Among these products, essential oils are attracting much attention. Essential oils are not currently used in livestock production in Canada and No rth America. However, they are extensively used in Europe because several European countries have banned the use of antibiotics and growth promoters in livestock diets. Moreover, the European Union (EU) has decided to ban by January 2006, the use of other feed antibiotics, including monensin ionophore, in livestock production. Consequently, in recent years, the essential oils market for livestock production has grown rapidly in the EU. Therefore, natural plant extracts such as essential oils may offer an interesting alternative means for manipulating the ruminal microbial ecosystem to improve feed efficiency in ruminants. The specific objectives of this project are: 1. To examine the opportunity of using essential oils as feed additives in ruminant diets; 2. To evaluate the effects of different types of essential oils on ruminal fermentation pattern, feed digestibility, ruminal microbial populations, proteolytic activity of ruminal bacteria, deaminative activity of ruminal bacteria, and methanogenic activ ity of ruminal bacteria. This research could be an effective means to improve efficiency of nitrogen use by dairy cows. The reduction of ruminal degradation of dietary nitrogen by essential oils will increase dietary amino acid supply to the intestines, w hich would contribute to meet the amino acid requirements of lactating dairy cows and increase milk protein production. By improving the use of dietary nitrogen in dairy cows, the need for protein supplements in dairy rations could be reduced, and therefo re help farmers to reduce feed costs. The decrease in protein degradation in the rumen will reduce ammonia production and urinary nitrogen excretion which would have favorable effects on the environment.