Potential of Enzymes to Improve Performance and Health of Broilers under a Mild Coccidial Vaccine Challenge

Enzymes have shown promising effects on performance and intestinal health in broilers (Toghyani et al., 2022). However, the dosage effect of enzymes and combination of different enzymes have not been extensively evaluated under the coccidial vaccine challenge condition. Therefore, a feeding study was conducted to examine the effect of dosage of xylanase+glucanase and the effect of its combination with a high level of phytase on growth performance, health, and welfare of broilers under a mild coccidial vaccine challenge. A total of 640 d-old Cobb 500 broiler chicks of mixed sex were assigned to 40-floor pens with eight replicates of 16 birds per dietary treatment. The five treatments were: unchallenged birds fed a basal diet containing 500 FTU/kg phytase (UC); challenged birds fed a basal diet containing 500 FTU/kg phytase (CC); CC + xylanase and glucanase at 100 g/t feed (XG100); CC + xylanase and glucanase at 200 g/t (XG200); CC + xylanase and glucanase at 100g/t and an additional 500 FTU/kg phytase, resulting in total phytase of 1000 FTU/kg (XG100+PHY) in starter, grower and finisher phases. Birds were fed pelleted feed and diets were based on wheat, soybean meal, barley and rye and formulated to meet breed standards considering the matrix values of phytase at 500 FTU/kg. The additional enzymes were added on top during feed mixing. Birds were given 1 mL/bird per os Eimeria spp. vaccine consisting of E. acervulina 5000, E. maxima 5000 and E. brunetti 2500 oocysts on d 9. The sex of the sampled birds was determined following the method described by England et al. (2021). The measured and analysed parameters were bird performance (d 0-8, 9-19, 20-35 and 0-35), where the female percentage was used as a covariate, excreta Eimeria spp. oocyst counts on d 14, intestinal lesions on d 16, litter moisture on d 17 and 35, and footpad dermatitis score (FPD) on d 35.

Reduced average weight gain (AWG), feed intake, increased FCR, Eimeria spp. oocyst counts, duodenal lesion scores and litter moisture observed in the CC group (d9-19; P < 0.05) indicates a successful coccidial vaccine challenge of the birds. XG100 enhanced (P < 0.05) AWG on d 20-35 and d 0-35 compared to the CC group. XG100 lowered (P < 0.05) FCR on d 0-8, d 9- 19, d 20-35 and d 0-35 compared to the CC group. XG100 reduced (P < 0.05) litter moisture content compared to the UC group and decreased (P < 0.05) FPD scores compared to the CC group on d 35. Birds fed XG100 had similar (P > 0.05) performance, FPD and litter moisture compared to XG200 and XG100+PHY, except for FCR on d 9-19 and FPD on d 35 whereby birds fed XG100+PHY had a higher (P < 0.05) FCR and FPD compared to the XG100 group. In addition, birds fed XG200 had a higher (P < 0.05) FPD on d 35 compared to the XG100 group. These findings suggest that dietary supplementation of XG100 on a basal diet based on wheat-barley-ryesoybean meal and containing phytase (500 FTU/kg) may enhance performance by increasing AWG and reducing FCR, and improve welfare by decreasing litter moisture content and FPD of birds under a mild coccidial vaccine challenge. However, increasing doses of the enzymes to XG200 and 1000 FTU/kg PHY may not additionally improve bird performance and health compared to XG100.

ACKNOWLEDGMENTS: The authors would like to thank BASF SE Germany, Poultry Hub Australia, and Eimeria Pty. Ltd., Australia, for supporting this project.