Research note: Cecal microbiota and growth performance in Hubbard JA 757 broilers with and without outdoor access

This study investigated the effect of outdoor access, starting from the 3rd week of age, on cecal microbiota and growth performance in medium-growing Hubbard JA757 broiler chickens. Forty-eight birds were assigned to two treatment groups: a control group (C) without outdoor access and an outdoor access group (OA), each with four replicate pens. Cecal samples were collected on day 56 and analyzed using full-length 16S rRNA gene sequencing. No significant differences were found in bacterial diversity (α-diversity) or in species-level relative abundance, nor in productive performance parameters including final body weight, carcass weight, breast weight, and leg weight. These findings suggest that the limited and relatively late outdoor exposure provided in this study was insufficient to induce measurable changes in the composition of the intestinal microbiota or in the growth performance of Hubbard JA757 broilers.