The present study was conducted to characterize the in vitro antimicrobial activities of 3 essential oils [oregano, rosemary, and a commercial blend of essential oils (BEO)] against pathogenic and nonpathogenic bacteria and to evaluate their effects on broiler chicken performances. The chemical composition of the essential oils was determined using the gas chromatography interfaced with a mass spectroscopy. The disc diffusion method, the minimum inhibitory concentration (MIC), and the minimum bactericidal concentration (MBC) were applied for the determination of antimicrobial activities of essential oils. In vivo study, a total of seven hundred fifty 1-d-old male broiler chickens were assigned to 6 dietary treatment groups: basal diet (control; CON), CON + 44 mg of avilamycin/kg (A), CON + 100 mg of rosemary essential oil/kg (ROS), CON + 100 mg of oregano essential oil/kg (OR), CON + 50 mg of rosemary and 50 mg of oregano essential oils/kg (RO), and CON + 1,000 mg of BEO/kg (essential oil mixture, EOM). The essential oils isolated from rosemary and oregano were characterized by their greater content of 1,8-cineole (49.99%) and carvacrol (69.55%), respectively. The BEO was mainly represented by the aldehyde (cinnamaldehyde) and the monoterpene (1,8-cineole) chemical groups. The results of the disc diffusion method indicated that the rosemary essential oil had antibacterial activity (P ≤ 0.05) against only 3 pathogenic bacteria, Escherichia coli (8 mm), Salmonella indiana (11 mm), and Listeria innocua (9 mm). The essential oil of oregano had antimicrobial activities (P ≤ 0.05) on the same bacteria as rosemary but also on Staphylococcus aureus (22 mm) and Bacillus subtilis (12 mm). Oregano essential oil had greater (P ≤ 0.05) antimicrobial activities against pathogenic bacteria than rosemary essential oil but they had no synergism between them. The BEO showed an increased antimicrobial activity (P ≤ 0.05) against all studied bacteria (pathogenic and nonpathogenic bacteria) except for Lactobacillus rhamnosus. The supplementation of the basal diet with avilamycin or essential oils improved (P ≤ 0.05) broiler chicken BW, BW gain, and G:F compared with the CON diet. There were no differences in growth performances among birds fed A, ROS, OR, RO, or EOM diets. In general, essential oils contained in rosemary, oregano, and BEO can substitute for growth promoter antibiotics. Although the 3 essential oils had different antimicrobial activities, they exhibited the same efficiency in broiler chickens.

This study was performed with growing chickens (4 to 22 d of age) to evaluate the effects of feeding a rye-based diet supplemented with commercial enzyme preparation containing xylanase and beta-glucanase (Quatrazyme HP, Nutri-Tomen, France) on small intestine wall morphology, bile acid composition, nutrient digestibility, and bird performance compared with unsupplemented rye- or corn-based diets. The rye-based diet decreased (P < or = 0.05) weight gain, feed intake, and feed efficiency and increased water intake compared with the corn-based diet. Moreover, rye consumption reduced crude fat and protein digestibility as well as apparent metabolizable energy (P < or = 0.05). The small intestine wall showed that villus length, width, and surface were decreased in broiler chickens fed the rye-based diet compared with those fed the corn-based diet. However, crypt morphometry parameters were not affected by diet type. The concentration of conjugated bile acids in the small intestine contents of broiler chickens fed the rye-based diet was decreased (P < or = 0.05) compared with those fed the corn-based diet. These findings suggest that feeding a rye-based diet reduces villus capacity for nutrient absorption and bile acid capacity for fat solubilization and emulsification, resulting in decreased bird performance. The addition of xylanase and beta-glucanase to the rye-based diet improved (P < or = 0.05) weight gain, feed intake, and feed efficiency, and decreased water intake. The digestibility of nutrients and apparent metabolizable energy were also increased (P < or = 0.05). Addition of xylanase and beta-glucanase increased (P < or = 0.05) villus size and the villus height-to-crypt depth ratio, as well as the concentration of conjugated bile acids (P < or = 0.05) in the small intestine contents. Exogenous enzymes improved nutrient digestibility and broiler chicken performance, probably by improving the absorption capacity ofthe small intestine through increased villus surface and intestinal concentration of conjugated bile acids.

-Corn-or wheat and barley-based diets were supplemented or not with xylanase and β-glucanase (Quatrazyme HP, Nutri-Tomen, France) and fed to broiler chickens (n = 12 per group) from 3 to 25 days of age. The unsupplemented wheat and barley-based diet reduced (P ≤ 0.05) weight gain and feed intake, and increased the feed conversion ratio as compared to the corn-based diet. Viscosity in the supernatant of the small intestine contents was increased (P ≤ 0.05), whereas pH and osmolality values decreased (P ≤ 0.05). Crude fat and protein digestibility were reduced as well as the apparent metabolizable energy (P ≤ 0.05). Moreover, wheat and barley consumption, when compared with the corn-based diet, produced an increase in the microflora of the caeca, with 10.0 vs. 8.9 log CFU·g -1 for facultative anaerobic bacteria, 6.5 vs. 5.6 log CFU·g -1 for E. coli and 9.7 vs. 8.3 log CFU·g -1 for Lactobacillus. The addition of xylanase and β-glucanase to the wheat and barley-based diet significantly reduced the viscosity of the small intestine contents and improved (P ≤ 0.05) weight gain, feed intake and feed conversion ratio. The digestibility of the nutrients, the apparent metabolizable energy and the osmolality of the small intestine contents were also increased without alteration in pH values. At the same time, the number of total facultative anaerobic bacteria and E. coli decreased significantly (P ≤ 0.05). In conclusion, the addition of xylanase and β-glucanase improves the digestibility of a wheat and barley-based diet, probably by reducing the viscosity of the intestine content and by impeding the growth of bacteria (total facultative anaerobic bacteria, E. coli). Abbreviations: AME, Apparent metabolizable energy; AME n , Apparent metabolizable energy to zero nitrogen balance; CFU, Colony forming units; DM, Dry matter; GE, Gross energy; HPAEC, High performance anion exchange chromatography; NSP, Non starch polysaccharides; RAV, Real applied viscosity; VFA, Volatile fatty acids.Résumé -Influence de la supplémentation du régime alimentaire par une association de xylanase et de -glucanase sur la digestibilité des nutriments, les conditions physico-chimiques dans l'intestin grêle et l'équilibre de la flore caecale chez le poulet nourri avec un aliment à base de blé et d'orge. Trente-six poulets de chair (Ross) sont, entre le 3 e et le 25 e jour d'âge, nourris soit avec un aliment témoin à base de maïs soit un aliment expérimental contenant du blé et de l'orge supplémenté ou non avec une association de xylanase et de β-glucanase (Quatrazyme HP, Nutri-Tomen, France). Le gain de poids et l'efficacité alimentaire sont plus faibles (P ≤ 0,05) chez les poulets nourris avec un régime à base de blé et d'orge que chez les témoins. La baisse des performances zootechniques est liée à une réduction de la pression osmotique, une diminution (P ≤ 0,05) de la digestibilité des lipides et des protéines et une baisse de l'énergie. En revanche, la viscosité du contenu intestinal, le nombre de bactéries anaérobies facultatives (10,0 vs....