Xylanase improves growth performance, enhances cecal short-chain fatty acids production, and increases the relative abundance of fiber fermenting cecal microbiota in broilers

Abstract

This study investigated the effects of xylanase and fiber on growth response, cecal short-chain fatty acids (SCFA) production, and cecal microbiota diversity in broilers. A total of 180 day-old chicks (Cobb 500) were randomly distributed in 30 pens (6 birds/pen). Six dietary treatments were tested using a completely randomized design in a 3 × 2 factorial arrangement (n = 5). The treatments included 3 levels of wheat bran (WB) as an additional fiber source in corn soybean meal-based diet, supplemented without or with xylanase (0.1 g/kg Econase-XT) besides 500 FTU/kg phytase and fed in 2 phases (starter, d 0–21 and finisher, d 22–35) in mash form. The three levels of WB used in this study were included at the concentration of 0 g/kg (WB 0%), 50 g/kg (WB 5%), and 100 g/kg (WB 10 %) in diet. Xylanase supplementation significantly (P < 0.05) increased the average daily gain (ADG) in the finisher phase and total period and increased (P < 0.05) average total gain in broilers (2025 vs 1943 g). Xylanase improved (P < 0.01) feed conversion ratio (FCR) in the starter phase while a significant interaction (P < 0.05) was found between WB and xylanase on FCR in the finisher phase and total period. A greater improvement in FCR in WB 5% and WB 10 % in response to xylanase compared with WB 0% indicated that high fiber diets were more responsive to supplemental xylanase. Independent of fiber level, xylanase increased (P < 0.01) cecal SCFA (86.6 vs. 63.4 μmol/g) compared to no xylanase group. Amplicon sequencing of V3-V4 region of 16S rRNA gene from cecal samples of d 35 revealed that xylanase had a trend (P = 0.08) for a greater number of operational taxonomic units and exhibited a trend (P = 0.054) for greater beta diversity compared to no xylanase group. Xylanase also increased the abundance of Ruminococcaceae, Lachnospiraceae and Lactobacillus salivarius compared with no xylanase groups (P < 0.05). It is concluded that xylanase can enhance the productive performance of broilers by improving feed efficiency and that some but not all responses are related to increased cecal SCFA and enhanced abundance of beneficial gut microbiota.