Supplementation of Enzyme and Probiotic Improved Growth Performance in Broilers under Necrotic Enteritis Challenge

Feed additives have a promising impact on broiler production in improving performance and reducing the incidence of diseases in the post-antibiotic era (Ayalew et al. 2022). However, there are limited data that illustrate the effect of feed additives on broiler performance under necrotic enteritis (NE) challenge. Therefore, this study was conducted to determine the impact of an enzyme (xylanase, 3000 U/kg) and a probiotic (Bacillus subtilis, 2.2 × 108 CFU/g) on growth performance and intestinal lesions of broilers under the NE challenge. A total of 630 d-old Cobb 500 mixed-sex broiler chicks were randomly distributed into five treatment groups, with nine replicates of 14 birds per pen in a completely randomised design. The treatments were: Non-challenged (NC); NE challenged control (CC); CC+Xylanase 300 g/t (CC+Xy); CC+Probiotic 500 g/t (CC+Pb); and CC+ Xylanase+ Probiotic (CC+Xy+Pb) in the starter, grower, and finisher phases. Birds were fed a corn-soy-based diet supplemented with phytase (100 g/t and 500 FTU/kg). Challenged birds were gavaged with Eimeria spp. on d 9 and Clostridium perfringens EHE-NE18 on d 14 and 15 according to Rodgers et al. (2015). Birds were sexed according to the method described by England et al. (2021) and the female percentage was used as a covariate for the performance analysis. Intestinal NE lesions were scored and recorded at d 16 and growth performance was measured from d 0 to 35. Data were subjected to a one-way analysis of variance using JMP 14.0 and significance was determined at P < 0.05 by the Tukey HSD test.

Before the challenge (d 0-8), average body weight gain (AWG), average feed intake (AFI) and feed conversion ratio (FCR) were not different (P > 0.05) between control groups, NC and CC. Birds in the groups CC+Xy, CC+Pb, and CC+Xy+Pb had a lower (P < 0.05) FCR compared to the control groups, whereas, only CC+Xy had a higher (P > 0.05) AWG than the control groups. Effective induction of the sub-clinical NE challenge was confirmed by decreased AWG, increased FCR, and duodenal lesions in the CC group (P 0.05) after the challenge. In the finisher phase (d 19-35), birds in the CC+Xy+Pb treatment had a lower (P < 0.05) FCR compared to the CC group. For the overall period (d 0-35), the CC group had a lower (P < 0.05) AWG and a higher (P < 0.05) FCR compared to the NC group. Birds in the treatment CC+Xy+Pb had a lower (P < 0.05) FCR compared to the CC group and maintained a similar (P > 0.05) AWG compared to the NC group and other additive groups. On d16, the birds in the group CC+Xy+Pb had a lower (P < 0.05) duodenal lesion score in female birds compared to the CC group and had similar (P > 0.05) duodenal, jejunal, and ileal lesions in both male and female birds compared to the NC group. These results suggest that the supplementation of xylanase in the starter phase may improve broiler performance. Overall, the combination of enzyme and probiotic in NE-challenged birds may enhance performance by improving AWG and FCR. This could be a result of the lower intestinal lesions and enhanced gut environment, which may have facilitated the maintenance of growth response in the CC+Xy+Pb group compared to the non-challenged treatment.

ACKNOWLEDGMENTS: The authors would like to thank Kemin Animal Nutrition and Health, Asia Pacific, Poultry Hub Australia, and Eimeria Pty. Ltd., Australia for supporting this project.