Effects of microbial-phytase co-fermentation of sorghum on growth performance, nutrient utilization, digestive enzyme activities and cecal microbiota in meat ducks.

This study evaluated the nutritional value and feeding effects of microbial-phytase co-fermented sorghum (MPCFS) in Cherry Valley meat ducks. MPCFS was prepared by fermentation with Bacillus subtilis, Candida utilis, and phytase. In experiment 1, 128 male ducks (22 days old) received a basal diet, diets replacing 30% of the basal diet with sorghum or MPCFS, or a nitrogen free diet to assess nutrients digestibility. In experiment 2, 240 male ducks (15 days old) were fed for 21 days with either a corn soybean meal diet or diets in which 70% of corn was substituted with sorghum or MPCFS. The results indicated that MPCFS significantly increased crude protein (CP), acid soluble protein (ASP), and ash in sorghum, while reducing phytic acid (PA) and fiber contents (P < 0.05). Moreover, MPCFS significantly improved the digestibility of CP, ether extract (EE), zinc (Zn), phosphorus (P), and gross energy (GE) (P < 0.05), alongside increasing the apparent metabolizable energy (AME) and the standardized ileal digestibility (SID) of Leu, Lys, Met, Val, His, and Trp (P < 0.05). In Experiment 2, compared with the sorghum group, the MPCFS diet significantly increased 35 day body weight (BW) and average daily gain (ADG), and decreased the feed-to-gain ratio (F/G) (P < 0.05). Furthermore, substituting corn with MPCFS significantly enhanced duodenal amylase, lipase and trypsin activities (P < 0.05). In the cecum, compared with the sorghum, MPCFS significantly increased cecal acetate, propionate, and butyrate concentrations (P < 0.05). Microbial analysis revealed that MPCFS improved cecal microbial α diversity in meat ducks, increased the relative abundance of Firmicutes and Phascolarctobacterium, and decreased that of Fusobacteriota, Bacteroidota, Desulfovibrio, and Streptococcus (P < 0.05). Collectively, MPCFS improved sorghum utilization in meat ducks by enhancing nutrient digestibility, digestive function, cecal short-chain fatty acid production, and gut microbial composition.