Aglycone soy isoflavones have notable immune-regulatory bioactivity, while glycosidic forms in soybean meal pose challenges for absorption. β-Glucosidase (EC 3.2.1.21) catalyzes the non-reducing terminal β-d-glucosidic bonds, releasing β-d-glucan and aglycones. This study evaluated the impact of enzymatically hydrolyzed soybean meal (ESM) using recombinant β-glucosidase from Aspergillus niger on the growth performance and intestinal immune function of broilers under Clostridium perfringens infection. Prior to the feeding trial, soybean meal was enzymatically digested with recombinant β-glucosidase, ensuring almost complete conversion of glycosides to aglycones. After a week of pre-feeding, a total 180 healthy AA broilers were randomly assigned to three groups—control, semi-replacement of ESM (50% ESM), and full-replacement of ESM (100% ESM)—with 6 replicates of 10 chickens, and the trial lasted 28 days. On the 36th day, broilers were challenged with 1 mL of 1 × 1010 CFU/mL Clostridium perfringens (Cp) via gavage for 3 days. The results showed that the substitution of ESM had no effect on the body weight gain of broilers but significantly reduced the feed consumption and feed-to-gain ratio (p < 0.01). The study revealed that Cp significantly disrupted jejunal morphology, while ESM significantly mitigated this damage (p < 0.05). Real-time PCR results demonstrated that compared to the Cp group, ESM restored Cp-induced intestinal barrier impairments (e.g., Occludin, Claudin-1, Muc2), normalized aberrant cellular proliferation (PCNA) and apoptosis (Caspase-1 and Caspase-3), and upregulated the expression of anti-inflammatory factor Il-10 while suppressing pro-inflammatory cytokines (Il-1β, Il-6, and Il-8) (p < 0.05). Moreover, flow cytometry analyses demonstrated that ESM promoted Treg cell-derived Il-10, which alleviated macrophage-derived inflammation. Substituting conventional soybean meal with β-glucosidase, enzymatically treated, significantly reduced feed consumption and alleviated the intestinal damage and immune dysfunctions induced by Clostridium perfringens infection in broilers.
