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Many herbal products (herbs and essential oils) are currently used as sensory additives and are intended to increase feed aroma or palatability. Moreover, several publications indicate that certain essential oils might have beneficial effects on animal performance and health status because of other properties such as: stimulation of digestive secretions, antimicrobial, coccidiostatic, anthelmintic, anti-inflammatory activities, and antioxidant properties. The aim of this study was to assess the effects of 2 different phytogenic products on performance, ileal nutrient digestibility, and composition of the intestinal microbiota. The 2 phytogenic products contained different essential oil mixtures (EOM) characterized by either menthol (Mentha arvensis), designated as EOM-M, or cinnamon aldehyde (Cinnamomum aromaticum), designated EOM-C, as main constituents. Three treatments consisted of control diet without EOM addition and diets supplemented with EOM-M or EOM-C. Reproducibility of the effects was examined in 4 trials with a total of 300 male castrated and female piglets weaned at 25 d of age.
The feed additives had no effect on feed intake or weight gain. Improvements (P < 0.05) in G:F were observed for EOM-M supplemented diets in 2 of 4 trials as well as for the combined data of all trials. These improvements were associated with higher (P < 0.05) apparent ileal digestibility of CP and of most amino acids. The effect of EOM-C on these response criteria was intermediate between control and EOM-M. Real-time PCR analysis of the gastrointestinal contents for 7 bacterial groups (Lactobacillus spp., Enterococcus spp., Clostridium coccoides and C. leptum cluster, Escherichia spp., and E. coli toxin estII) indicated no effect of treatments on the gastrointestinal microbiota.
It was concluded that EOM-M consistently improved feed efficiency in weaned piglets, and it was sssociated with improved ileal protein and amino acid digestibility. In general, however, the effectiveness of EOM as feed additives differs considerably depending on the constituents.
K Maenner, W Vahjen and O Simon, 2011. Journal of Animal Science, 89(7): 2106-2112. http://dx.doi.org/10.2527/jas.2010-2950