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Gram‐negative bacteria contamination of feed can occur at all the stage of feed production, storage, transportation and utilization. Lipopolysaccharide (LPS) is a major toxic metabolite of Gram‐negative bacteria. The aim of this study was to explore the effect of dietary resveratrol on the duck ileitis caused by LPS and its optimum addition level in diet. The results showed that LPS‐induced duck ileitis with the destruction of intestinal structure, oxidative stress, mitochondrial dysfunction, inflammatory response and permeability alteration. Dietary resveratrol alleviated LPS‐induced intestinal dysfunction and the increase of intestinal permeability by linearly increasing mRNA levels of tight junction protein genes (Claudin‐1, Occludin‐1, ZO‐1) (p < 0.05) and protein expression of Claudin‐1 (p < 0.01). In addition, dietary resveratrol improved the antioxidant capacity of duck ileum by reducing the production of MDA and increasing the activity of T‐SOD (p < 0.01) and CAT. Lipopolysaccharide increased Keap1 at mRNA and protein level (p < 0.01) and decreased the protein level of Nrf2 (p < 0.05). Dietary resveratrol significantly downregulated expression of Keap1 and upregulated expression of Nrf2 in duck (p < 0.05). Dietary resveratrol suppressed the TLR4/NF‐κB signalling pathway and the expression of its downstream genes including IKK, TXNIP, NLRP3, Caspase‐1, IL‐6 and IL‐18. Meanwhile, the levels of inflammatory cytokines (IL‐6, IL‐18 and TNF‐α) showed a linearly decrease (p < 0.01) with increasing dietary resveratrol level. These results demonstrated that resveratrol alleviated the LPS‐induced acute ileitis of duck through Nrf2 and NF‐κB signalling pathways, and the dietary resveratrol of 500 mg/kg is more efficiently. [ABSTRACT FROM AUTHOR]

The antimicrobial peptide fowlicidin-2 identified in chicken is a member of the cathelicidins family. The mature fowlicidin-2 possesses high antibacterial efficacy and lipopolysaccharide (LPS) neutralizing activity, and also represents an excellent candidate as an antimicrobial agent. In the present study, the recombinant fowlicidin-2 was successfully produced by Escherichia coli (E. coli) recombinant expression system. The gene encoding fowlicidin-2 with the codon preference of E. coli was designed through codon optimization and synthesized in vitro. The gene was then ligated into the plasmid pET-32a(+), which features fusion protein thioredoxin at the N-terminal. The recombinant plasmid was transformed into E. coli BL21(DE3) and cultured in Luria-Bertani (LB) medium. After isopropyl-β-D-thiogalactopyranoside (IPTG) induction, the fowlicidin-2 fusion protein was successfully expressed as inclusion bodies. The inclusion bodies were dissolved and successfully released the peptide in 70% formic acid solution containing cyanogen bromide (CNBr) in a single step. After purification by reverse-phase high-performance liquid chromatography (RP-HPLC), ∼6.0 mg of fowlicidin-2 with purity more than 97% was obtained from 1 litre of bacteria culture. The recombinant peptide exhibited high antibacterial activity against the Gram-positive and Gram-negative bacteria, and even drug-resistant strains. This system could be used to rapidly and efficiently produce milligram quantities of a battery of recombinant antimicrobial peptides as well as for large-scale production. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:369-374, 2015 [ABSTRACT FROM AUTHOR]

Intensive breeding of broilers met the increasing demands of human for broiler products, but it raised their increased susceptibility to various stressors resulting in the disorder of lipid metabolism. Pterostilbene, the methoxylated analogue of resveratrol, exhibits astonishing functions of antioxidant, anti‐inflammatory and glycolipid regulatory. The study aimed to elucidate the protective effects of pterostilbene on broiler liver and to explore the potential mechanisms. A total of 480 one‐day‐old male Arbor Acres (AA) broilers were randomly divided into four groups: the control group (basal diet) and pterostilbene groups (PT200, PT400, and PT600 feeding with basal diet containing 200, 400 and 600 mg/kg pterostilbene, respectively). The results showed that the dietary pterostilbene supplementation significantly improved the ADG of broilers. Dietary pterostilbene supplementation regulated the expression levels of the genes Sirt1 and AMPK and the downstream genes related to lipid metabolism to protect liver function and reduce lipid accumulation in broilers. Dietary pterostilbene supplementation upregulated the expression levels of the Nrf2 gene and its downstream antioxidant genes (SOD, CAT, HO‐1, NQO‐1, GPX) and phase II detoxification enzyme‐related genes (GST, GCLM, GCLC). Collectively, pterostilbene was confirmed the positive effects as a feed additive on lipid metabolism and antioxidant via regulating Sirt1/AMPK and Nrf2 signalling pathways in broilers. [ABSTRACT FROM AUTHOR]