Intestinal morphometric changes associated with the use of non-antibiotic feed additives in broiler chicks challenged with Salmonella Enteritidis
Non-antibiotic feed additives stand as a potential alternative for antimicrobial growth promoters, but their effects in the gastrointestinal tract of broiler chicks suffering early infection are poorly understood. This study aimed to investigate the effects of two non-antibiotic feed additives (a postbiotic and a sanguinarine-based phytobiotic) on the gut morphology and body weight gain of broiler chicks challenged with <italic>Salmonella enterica </italic>serovar Enteritidis (SE). Birds (n=144) were distributed according to a 2 × 3 factorial in a completely randomized design with the following treatments: non-challenged chicks fed control diet (SHAM-DCO), postbiotic (SHAM-PFC), or sanguinarine-based compound (SHAM-SAN) and SE-challenged chicks fed control diet (SE-DCO), postbiotic (SE-PFC), and sanguinarine-based compound (SE-SAN). Birds from each treatment were euthanized at 3-, 7-, and 14-days post inoculation and samples were collected for SE counting and intestinal morphometry. Weight gain was determined at 14 days post-inoculation. Lower (<italic>p</italic> ≤ 0.05) <italic>Salmonella</italic> counts were observed in birds fed diets containing PFC at 3- and 7-days post inoculation. SE-challenged chicks showed greater crypt depth (<italic>p</italic> ≤ 0.05) and lamina propria thickness (<italic>p</italic> ≤ 0.05) and smaller villus:crypt ratio (<italic>p</italic> ≤ 0.05) at the different sampling periods. Overall, birds fed PFC or SAN showed decreased lamina propria thickness (<italic>p</italic> ≤ 0.05), greater villus height (<italic>p</italic> ≤ 0.05), villus:crypt ratio (<italic>p</italic> ≤ 0.05), and larger villus area (<italic>p</italic> ≤ 0.05) compared with those fed the control diet (DCO). SAN supplementation improved body weight (<italic>p</italic> ≤ 0.05) and weight gain (<italic>p</italic> ≤ 0.05) until 14 days post-hatch compared with the control diet. Both feed additives (PFC and SAN) improved birds’ response to post-hatch <italic>Salmonella</italic> Enteritidis infection, evidenced by beneficial changes in gut morphology. These effects highlight the potential of these feed additives to improve gut health of broiler chicks during the initial rearing phase.