This study evaluated the effects of recombinant xylanase Xyn1m, derived from Fibrobacter succinogenes and expressed in Pichia pastoris , on growth performance, intestinal morphology, and gut microbial characteristics in broilers. A total of 144 one-day-old broilers were randomly allocated to three treatments with 12 replicates per treatment (4 birds per replicate): a control group (basal diet), a low-dose Xyn1m group (6,800 IU/kg), and a high-dose Xyn1m group (13,600 IU/kg). Supplementation with high-dose Xyn1m significantly increased body weight at 49 d and average daily gain during the 29–49 d growth phase compared with the control group ( P < 0.01), whereas feed intake and feed conversion ratio were not affected. High-dose Xyn1m reduced duodenal crypt depth ( P < 0.05), while ileal morphology remained unchanged. In the duodenum, Xyn1m supplementation increased the Shannon index and reduced the Simpson index of the microbial community ( P < 0.05), although no significant differences were detected in the relative abundance of dominant bacterial taxa. Beta-diversity analysis showed that high-dose Xyn1m altered the duodenal microbial community structure. In contrast, no significant differences were observed in microbial diversity or community composition in the ileum, except for a linear reduction in the relative abundance of Acinetobacter ( P < 0.05). Functional prediction using PICRUSt2 indicated enrichment of pathways associated with nutrient transport, carbohydrate metabolism, and energy production in the duodenal microbiota of the high-dose group, whereas predicted functional changes in the ileum were limited. These results indicate that dietary supplementation with 13,600 IU/kg recombinant xylanase Xyn1m improved growth performance during the mid-growth stage and enhanced duodenal microbial diversity and intestinal morphology, while exerting minimal effects on distal ileal microbial functions.
Liu et al. (Wed,) studied this question.