Dietary levan as a feed additive: Effects on growth performance, meat quality, immune response, and gut health in broiler chickens

This study investigated the effects of dietary supplementation with levan a microbial fructan-type exopolysaccharide, as a feed additive on growth performance, meat quality, intestinal microflora composition, intestinal histomorphometry, lymphoid organ, and the formation of blood immune cell populations in broiler chickens. A total of 1400 day-old Ross 308 broiler chicks were randomly divided into five experimental groups, each comprising eight replicates of 35 birds. The control group (C) received the basal diet without levan whereas the experimental groups received a basal diets supplemented with 0.1 % (L0.1), 0.25 % (L0.25), 0.5 % (L0.5) or 1 % (L1) levan throughout the rearing period. Dietary levan supplementation significantly improved growth performance parameters compared with the C group. However, higher inclusion levels (0.5 and 1 %), resulted in a significant (P < 0.05) deterioration of certain sensory meat quality traits. Cecal microbiological analysis revealed a significant (P < 0.05) increase in Lactobacillus spp. counts in levan supplemented groups. Histomorphometric evaluation of the ileum (IL) showed that levan significantly (P < 0.05) increased the villus surface area and the villus height to the crypt depth ratio (V/C). The lymphoid organs morphometry and the proportions of blood lymphocytes and monocytes were not significantly affected, suggesting that there was no measurable immunomodulatory activity under the conditions of this study. In summary, dietary levan has the potential to improve the growth performance, beneficial intestinal microbiota, and intestinal morphology of broilers. However, meat sensory characteristics may be adversely affected by excessive concentrations. Further research is required to completely understand the mechanisms that underlie these effects and optimize inclusion levels.