The effects of dietary supplementation of pre-microencapsulated Enterococcus fecalis and the extract of Camellia oleifera seed on growth performance, intestinal morphology, and intestinal mucosal immune functions in broiler chickens

The objective of this study was to investigate the effects of microencapsulated Enterococcus fecalis (MEF) and the extract of Camellia oleifera seed (ECOS) on growth performance, morphological parameters and gene expressions related to barrier functions of the intestinal mucosa in broiler chickens. 160-day-old Arbor Acres male broilers were randomly allotted to 4 treatments with 8 replicates of 5 chicks in a 2 × 2 factorial arrangement, evaluating two levels of MEF (0 and 10 g/kg), and two levels of ECOS (0 and 300 mg/kg). The results showed that there was no significant interaction effect of MEF and ECOS on growth performance, morphometric parameters of jejunum and ileum, and mRNA expression of MUC2, occludin and claudin-1 in jejunum and ileum mucosa. Compared with other groups, diet supplemented with MEF significantly improved FCR from days 21 to 42, and significantly improved ADG from days 0 to 42. Dietary MEF significantly increased villus height and villus height to crypt depth ratio in jejunum and ileum, the concentrations of sIgA, IL-2, IL-6, TNF-α, and significantly up-regulated the gene expression of sIgA, MUC2, occludin and claudin-1 in jejunum and ileum mucosa. The interaction effect of MEF and ECOS was significant on the concentrations of sIgA, IL-2, IL-6, TNF-α in jejunum mucosa on day 42 and on the concentrations of sIgA, IL-2, TNF-α in ileum mucosa on day 42. These results indicated that MEF can improve growth performance and enhance intestinal barrier functions by improving its morphological development, increasing cytokine level, and up-regulating the gene expressions of sIgA, MUC2, occludin and claudin-1. But ECOS had slightly beneficial effects on growth performance and intestinal barrier functions.