Dietary supplementation of endo-1,4-ß-D-mannanase improves turkey growth through enhancement of immune response and jejunal barrier integrity

In-feed beta-mannanase supplementation has been used for decades to improve gut health and growth performances in poultry, yet its underlying molecular mechanisms are not completely defined. The aim of the present study was to determine the effect and potential mode of action of a new endo-1,4-β-D-mannanase (Natupulse® TS, NPU) on gut integrity and growth performances of turkeys. A total of 640 one-day-old male Hybrid Converter poults were randomly assigned to two dietary treatments without (control, CON) or with Natupulse® TS (NPU, 800 TMU/kg feed) for a 49 day-trial, each treatment having 16 replicate pens of 20 birds each. Body weight (BW), BW gain (BWG), feed intake (FI), and feed conversion ratio (FCR) and intestinal permeability using fluorescein isothiocyanate-dextran (FITC-d) were measured on days 21 and 49. Jejunal samples (16 birds/treatment) were analyzed for markers of stress, inflammation, and gut barrier integrity using real-time quantitative PCR and immunoblot. Dietary NPU supplementation significantly reduced serum FITC-D levels in turkey at day 49 and increased BWG at both day 21 and day 49 compared to the CON group. Molecular analyses showed that dietary NPU supplementation significantly increased jejunal protein levels of HSP60/70/90 on day 21. On day 49, HSP60 remained unchanged, HSP70 was high and HSP90 protein levels were significantly decreased compared to the CON diet. In-feed NPU administration significantly downregulated the jejunal expression of IL8, IL18, Crp and Tnfsf4 genes on day 21, and only IL8 gene on day 49. In addition, NPU supplementation decreased jejunal protein levels of claudins (CLDN1/4/5) on day 21 and CLDN5 on day 49. The expression of genes coding for gap junction proteins was also affected by NPU supplementation, with a significant downregulation of Gja1, Gjb1, Gjc1, and Gjd2 on day 21, and Gjc1 and Gjd2 on day 49. Dietary supplantation of NPU significantly downregulated the jejunal expression of the adherens junction protein afadin ( afdn1) gene on day 49 compared to the CON group. In summary, dietary NPU supplementation improved growth performance and jejunal barrier integrity potentially through modulation of the expression of HSPs, pro-inflammatory cytokines, tight junction, gap junction, and adherens junction proteins.