This study was conducted to evaluate the impacts of brewer’s grains (BG) on growth performance, apparent nutrient digestibility, immunity, antioxidant capacity, and fecal microbiota of Simmental crossbred cattle and the economic benefits. A completely randomized design was adopted in our study. Twenty-four 15-month-old finishing Simmental crossbred male cattle (body weight, 433.43 ± 32.47 kg) were randomly assigned to three groups: control group (basal diet), 10% BG group (supplemented with 10% BG on a dry matter basis), and 15% BG group (supplemented with 15% BG on a dry matter basis). The trial lasted for 48 days, with serum samples collected on days 24 and 48 and fecal samples collected from days 46 to 48. Diets did not influence the average daily gain, dry matter intake, feed efficiency, and serum antioxidant parameters (p > 0.05). The 15% BG group showed significantly higher acid detergent fiber digestibility (p < 0.01) and elevated serum albumin levels on day 48 (p = 0.047) compared with the control group. As for fecal microbiota, there was a lower Chao index (p = 0.040) and a higher abundance of Romboutsia in the 15% BG group (p = 0.025). Moreover, the feed costs of cattle fell by 9.34% and 14.66% after 10% and 15% BG supplementation, respectively. On the whole, BG supplementation demonstrated no significant effects on growth performance or animal health in finishing cattle. The 15% inclusion level demonstrated the greatest cost reduction potential. We, therefore, recommend adopting 15% BG supplementation as the optimal strategy to enhance economic returns in cattle production systems.

This study comparatively analyzed the spatial heterogeneity of the gut microbiome across gastrointestinal segments in Changle geese versus yellow-feathered broilers to discover their links with growth and intestinal development. Twelve 63-day-old male yellow-feathered broilers and twelve 70-day-old male Changle geese were selected. Body weight (BW), slaughter weight (SW), absolute lengths of the small intestine (LSI) and cecum (LC), and their relative lengths normalized to body size (RLSI/RLC) were measured. Additionally, 16S rDNA sequencing of crop, proventriculus, gizzard, jejunum, cecum, and rectum microbiota was conducted to assess microbial diversity, composition, and its correlation with phenotypes. Results demonstrated higher BW, SW, LSI, LC and lower RLSI and RLC in geese versus broilers (p < 0.001). Alpha diversity analysis revealed lower microbial richness and diversity in broilers across most gastrointestinal segments (p < 0.05), while beta diversity analysis confirmed distinct community structures between two species (p = 0.001). Firmicutes dominated broiler gut microbiota (94.49%), whereas geese exhibited greater phylum-level diversity (p < 0.05). Random forestry analysis identified Top 15 core Amplicon Sequencing Variants in both the cecum and rectum, with ASV12260 (unclassified Lachnospiraceae) and ASV12412 (uncultured Faecalibacterium sp.) as key biomarkers. Correlation analyses found 21 phenotype-related ASVs (p < 0.05). Specially, two Lactobacillus ingluviei strains showed negatively correlated with LSI and RLSI in the chicken foregut (p < 0.05). And two Gallibacterium anatis strains were associated with RLSI, with one strain also showing an inverse correlation with LSI in the goose foregut (p < 0.05). Interestingly, one Peptococcus strain was negatively correlated with BW and SW, while the other was inversely associated with LC and RLC in the goose hindgut (p < 0.05). These findings provide insights into species-specific distribution patterns of gut microbiota across poultry species and their correlation with growth performance and intestinal development, developing a theoretical foundation for advancing avian digestive physiology research and optimizing feeding strategies.