**6. Beneficial nutritional effects of EO**

### **6.1 In broiler chickens**

EOs are natural bioactive molecules that can be included as alternatives to antibiotics during broiler rearing. Results published by Puvača et al. [50] confirmed that these compounds have beneficial effects on nutrient digestibility, microbiota, and gut function. Authors also suggested that EOs have positive effects, but knowledge of their use in poultry feed is still limited and requires further research.

### **6.2 In ruminants**

EOs could be used as additives in ruminant feed, to modify the activity of microorganisms responsible for ruminal fermentations and to improve digestion in small ruminants.

Essential oils have been shown to exert beneficial effects on ruminal fermentations. In fact, these molecules are involved in improving the amino acids' quantity available for animal's needs, increasing the volatile fatty acid (VFA) levels, providing sources of energy for animals, and reducing methane and ammonia emissions [51]. These results are similar to those published by Jedidi et al. [12] and Selmi et al. [13] who worked on the effect of essential oils from many plants. These authors found that the inclusion of volatile compounds, at reasonable doses, stimulated parameters of ruminal fermentation in vitro, such as digestibility of organic matter (DOM), metabolisable energy (ME), and volatile fatty acids (VFA). In addition, EOs exerted the decrease in greenhouse gas emissions in a dose-dependent manner. The authors mentioned that all of these beneficial effects of essential oils are attributed to the synergistic effects of these components.

In this respect, a mixture of volatile compounds extracted from several aromaticplants has been shown to significantly improve food bioavailability. This beneficial effect exerted by this preparation is due to the changes in the intestinal ecosystem [52].

In the field of animal production, EOs are mainly used to improve zootechnical performance, such as growth rate, consumption index (CI), feed intake level, feed digestibility, and animal health status [53].

*Phytochemistry, Medicinal Uses, and Beneficial Nutritional Effects of Essential Oils DOI: http://dx.doi.org/10.5772/intechopen.112696*
