Effects of rearing system and narasin on growth performance, gastrointestinal development, and gut microbiota of broilers

This study was conducted to evaluate the effects of 3 rearing systems ( FL : flooring litter rearing, MC multilayer cage PN plastic net rearing) with or without supplemental narasin on growth performance, gastrointestine development and health broilers. A total 2,400 one-day-old Ross 308 mixed-sex broilers (1:1 ratio males females) were used in a completely randomized design utilizing × 2 factorial arrangement treatments, 12 replicates per treatment. Each replicate for FL, MC, consisted 34 birds floor pen, 30 cage, 36 respectively, ensuring same stocking density (12 birds/m ) across systems. Results showed that lower ADG (average daily gain), ADFI feed intake), FCR (feed conversation ratio) observed group than those other from 1 d age P < 0.05). Narasin inclusion diets decreased significantly Multilayer reduced relative weight gizzard Compared duodenum, jejunum, ileum The mRNA expression levels ileal IL-1? IFN-? higher TNF-? Different changed microflora structure system increased microbial diversity abundance Actinobacteria . combined Proteobacteria In conclusion, reared had body weight. poorer intestinal condition, , but better FCR. appeared be propitious gastrointestinal health. improved