In vitro sensitivity of poultry Brachyspira isolates to essential oil components and in vivo reduction of Brachyspira intermedia in rearing pullets with cinnamaldehyde feed supplementation
Vande Maele, Lien
De Pauw, Nele
Biology and Life Sciences | minimal inhibitory concentration | essential oil cinnamaldehyde | Brachyspira intermedia
Cecal enteritis due to Brachyspira infections tends to be chronic in laying hens. Limited availability of antimicrobial drugs for use in laying hens emphasizes the need for alternative control measures. A broth microdilution method was used to determine the antimicrobial susceptibility of 20 Brachyspira intermedia field isolates from laying hen flocks to components of essential oils (EO). Minimal inhibitory concentration (MIC) distributions, obtained for eight EO components, were all monomodal. Cinnamaldehyde had the lowest MIC values (40-80 mg/l), followed by nerolidol, capsaicin, carvacrol and thymol (80-320 mg/l), eugenol (160-640 mg/l) and linalool (320-1280 mg/l). The MIC ranges of piperine were mostly above the test-range of 1280 mg/l. In an in vivo experiment, coated cinnamaldehyde was supplemented to the feed of rearing pullets. A completely randomized experimental design with 4 treatments and 3 replicates each (replicate = group of 7 one-day-old birds) was applied. The negative and positive control birds received a conventional feed during the whole trial. The positive control group was orally inoculated on 3 consecutive days (day 22, 23 and 24) with 1 ml 1.0 x 108 cfu/ml of a B. intermedia field isolate. Two treatment groups (preventive and curative), identically inoculated, were fed the coated cinnamaldehyde supplemented feed (final cinnamaldehyde concentration in the feed of 500 ppm), the preventive group from day 1 and the curative from day 25. On day 32, ceca were collected for bacteriologic B. intermedia enumeration. The number of Brachyspirapositive birds and the mean enumeration of Brachyspira cells was decreased (P < 0.05) in the curative treated group versus the positive control group. The in vitro results of the present study demonstrate the potential of EO components as antimicrobials against poultry Brachyspira isolates, including isolates with acquired resistance for classic antimicrobial drugs. Reduction of Brachyspira colonization in young pullets was obtained, on a curative way, in an in vivo study using feed supplemented with coated cinnamaldehyde. Further studies are necessary to investigate the mode of action of the coated cinnamaldehyde in reducing Brachyspira colonization of the ceca.