Effects of Rearing System and Narasin on Growth Performance, Gastro-intestinal Development and Gut Microbiota of Broilers

Abstract This study was conducted to evaluate the effects of three rearing systems (FL: flooring litter rearing, MC: multilayer cage rearing, PN: plastic net rearing) with or without supplemental narasin on growth performance, gastro-intestine development and health of broilers. A total of 2,400 one-day-old Ross 308 mixed-sex broilers (1:1 ratio of males and females) were used in a completely randomized design utilizing a 3 × 2 factorial arrangement of treatments, with 12 replicates per treatment. Each replicate for FL, MC and PN consisted of: 34 birds per floor pen, 30 birds per cage, and 36 birds per net pen, respectively, ensuring the same stocking density (12 birds/m2) across the three systems. Results showed that lower ADG (average daily gain), ADFI (average daily feed intake) and FCR (feed conversation ratio) observed in the MC group than those of the other two systems from 1 to 36 days of age (P