Optimization of Compound Ratio of Exogenous Xylanase and Debranching Enzymes Supplemented in Corn-Based Broiler Diets Using In Vitro Simulated Gastrointestinal Digestion and Response Surface Methodology

SIMPLE SUMMARY: Arabinoxylan (AX), making up 50% or more of the total carbohydrates, is the primary antinutritional factor in corn and related by-products. It is particularly fortified with substituents, being more populated than in other cereal grains. These properties may be overcome by the action of xylanase. More importantly, the complete enzymatic degradation of AX demands the synergistic combinations with debranching enzymes due to its complicated and multi-branched structure. We predicted the optimal zymogram of exogenous xylanase, arabinofuranosidase, and feruloyl esterase supplemented in corn AX for efficient hydrolysis using the in vitro simulated gastrointestinal digestion model, thus highlighting the compound complementarity of debranching enzymes. It was a bold technical attempt to rapidly target, alleviate or eliminate antinutritional factors by multi-enzyme cocktails based on substrate specificity. This may provide guidance for the efficient promotion and application of related feed ingredients to reduce excessive costs in the broilers industry. ABSTRACT: This experiment aimed to explore the zymogram of endo-xylanase (EX) and debranching enzymes (arabinofuranosidase [EA] and ferulic acid esterase [EF]) supplemented in the corn–soybean meal-based diet of broilers. An in vitro simulated gastrointestinal digestion model was adopted. According to single-factor, completely random design, the optimal supplemental levels of individual carbohydrase were determined by reducing sugars (RS) and in vitro dry matter digestibility (IVDMD). Response surface method (RSM) was used to predict the proper compound ratio of three carbohydrases. Results showed that shifts were different for feedstuffs such as corn–soybean meal–distillers dried grains with solubles, corn hull, and wheat bran, revealing that the net increase of RS or IVDMD distinctly dropped when degrading corn and related by-products by EX (p < 0.05). There was a significant quadratic relationship between the above response metrics and addition levels of each enzyme (p < 0.05). The determined dosage was 54 U/g EX, 5.0 U/g EA, and 0.4 U/g of EF, respectively. The optimistic zymogram of carbohydrases in corn basal substrates was judged by the IVDMD screening (R(2) = 0.9089, p < 0.001). Conclusively, the in vitro assay and RSM were convenient and rapid methods for the optimization of xylan-degrading zymogram, and also testified asthenic hydrolysis of corn arabinoxylan by EX, thus highlighting the synergistic combinations with debranching enzymes.