Effect of xylanase and a blend of essential oils on performance and Salmonella colonization of broiler chickens challenged with Salmonella Heidelberg

The present experiment examined the influence of xylanase supplementation and a blend of essential oils (EO; cinnamaldehyde and thymol) on performance and Salmonella horizontal transmission in broiler chickens challenged with Salmonella. Two thousand 1-d-old broiler chicks were randomly assigned to 5 dietary treatments (8 pens/treatment of 50 male broilers each). Four dietary treatments were challenged with Salmonella: 1) control, 2) basal diets supplemented with EO, 3) basal diet supplemented with xylanase (2,000 U/kg of feed), and 4) basal diet supplemented with a combination of EO and xylanase (2,000 U/kg of feed). One treatment served as an unchallenged control and was not supplemented with either additive. Broiler starter and finisher diets, based on wheat and soybean meal, were formulated, pelleted, and fed ad libitum. At d 1, before placement, half of the birds from each pen were tagged and dosed with Salmonella enterica serovar Heidelberg (5 x 10(5) cfu/mL). On d 42, 5 random untagged birds from each pen were killed and their ceca removed and tested for Salmonella. Performance data were analyzed as a completely randomized design using GLM. The frequency of positive Salmonella in the untagged birds was compared between treatments by using a chi-squared test of homogeneity. Challenging the birds with Salmonella had no effect (P > 0.05) on any of the measured performance parameters. Xylanase and EO supplementation improved (P < 0.05) the 42-d BW gain and feed efficiency, with no effect (P > 0.05) on feed intake, compared with that of the control treatment. Xylanase supplementation improved (P < 0.05) BW gain and feed efficiency compared with the results of EO supplementation. The combination treatment of xylanase and EO numerically improved BW gain and feed efficiency compared with the xylanase treatment. Xylanase and EO supplementation reduced (P < 0.05) the incidence of horizontal transmission of Salmonella infection between birds by 61 and 77%, respectively, compared with the control. The results of the current study suggested that dietary addition of EO and xylanase could improve broiler performance and contribute to food safety by lowering the incidence of horizontal transmission of Salmonella infection.