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Essential oils, such as polyphenols, are a new class of feed additives. The possible mechanisms of action of those herbal extracts in animals are related to alteration of the intestinal microbiota, increased digestibility and absorbance of nutrients, as well as antioxidative and immunomodulatory activities. In this study, RES (containing resveratrol from mulberry and Japanese knotweed) and PEP (containing oregano, anise, orange peel, and chicory essential oils), were used as phytogenic feed additives. Resveratrol a type of natural polyphenol and aromatic phytoalexin found predominantly in grapes, berries (mulberries), and Japanese knotweed. A study was conducted to evaluate the effects of resveratrol and essential oils from medicinal plants on the growth performance, immunity, digestibility, and fecal microbial shedding of weaned piglets. A 4-wk experiment was conducted with a total of 48 newly weaned piglets (crossbred ((LandracexYorkshire)x Duroc), mean body weight 8 kg, 28 d of age) in order to evaluate the effects of the resveratrol and an essential oil blend as alternatives to antimicrobial feed additives such as apramycin. The piglets were randomly allotted to four dietary treatments with 3 replications of 4 piglets each. The dietary treatments were NC (negative control; basal diet), PC (positive control; basal diet + 0.002% apramycin), T1 (basal diet + 0.2% resveratrol), and T2 (basal diet + 0.0125% essential oil blend). All piglets were orally challenged with 5 ml culture fluid containing 2.3x108 cfu/ml of Escherichia coli KCTC 2571 and 5.9x108 cfu/ml Salmonella enterica serovar Typhimurium.
The PC group (P<0.05) showed the highest average daily gain (ADG) and average daily feed intake (ADFI) throughout the experimental period, although feed conversion ratio (FCR) was improved in the T1 group (P>0.05). Serum IgG level was increased in the T1 group, whereas TNF-α levels was reduced in the supplemented groups compared to control (P<0.05). The PC diet improved the dry matter (DM) digestibility, whereas PC and T2 diets improved nitrogen (N) digestibility compared to NC and T1 diets (p<0.05). Fecal Salmonella and E. coli counts were reduced in all treatment groups compared to control (P<0.05). Fecal Lactobacillus spp. count was increased in the T2 group compared to others (P<0.05).
In conclusion, the results showed a strong potential of resveratrol as antibiotic alternatives for reversing the adverse effects of weaning stress on growth performance, immunity and microbial environment in E. coli and Salmonella-challenged piglets. Further feeding trials using resveratrol and essential oils at different inclusion rates are required in order to better understand the effects of such additives as antibiotic alternatives as well as to elucidate their mechanisms of action.
Effects of resveratrol and essential oils on growth performance, immunity, digestibility and fecal microbial shedding in challenged piglets.(2013). S. T. Ahmed, M. E. Hossain1, G. M. Kim, J. A. Hwang, H. Ji and C. J. Yang. Asian Australas. J. Anim. Sci. Vol. 26, No. 5; 683-690 http://dx.doi.org/10.5713/ajas.2012.12683.