Effects of plant polyphenols and mannan-oligosaccharides on growth performance, antioxidant defense system and inflammatory responses of ileal mucosa in Escherichia coli Challenged piglets

The objective of the current study was to evaluate the possible protective effects of nutritional supplements (plant polyphenols (PP) mixture containing anthocyanin, catechins, chlorgenic and oleuropein as active ingredients, mannan oligosaccharide (MOS) and PP+MOS) on growth performance, systemic antioxidant capacity and gut health in piglets under Escherichia coli challenged condition. Ninety six weanling piglets (Stambo HBI Dalland 40) (22-d-old) were homogenously allocated to 24 pens and fed a basal diet for one week. After the adaptation period, piglets were divided into 4 treatments (6 replicates with 4 piglets per treatment) and fed a basal diet or the basal diet supplemented with 0.1% of PP, MOS or PP+MOS for 6 weeks. At 21 and 25 d, half of the piglets in each treatment were orally inoculated with 4 ml of E.coli (1×109cfu/ml) or same amount of saline water. Plasma samples collected at 7, 21, 25, 27 and 34 d and ileac mucosa samples prepared at 25 and 27 d were determined for antioxidative property and intestinal inflammatory responsive parameters. Dietary PP+MOS worsened the feed efficiency throughout the experiment. Compared to PP+MOS treatment, control group had better feed conversion ratio (FCR) during first two weeks, dietary MOS improved feed efficiency during 7 - 14 d, 0 - 34 d and 0 - 42 d, and dietary PP decreased FCR throughout the trial. Supplementation of PP markedly enhanced the systemic antioxidant property with higher total antioxidant capacity and lower malondialchehyche content compared to control or PP+MOS treatment at 21 d. At 4 d post infection (DPI), challenge didn’t affect antioxidant capacity, dietary PP or MOS increased plasma GSH-Px activity. Increased plasma Malondialdehyde content, decreased plasma total antioxidant capacity (TAOC) and catalase (CAT) activity were observed at 6 DPI. Reduced TAOC were seen in challenged piglets, dietary PP or MOS increased TAOC compared to PP+MOS diet, dietary PP or PP+MOS increased CAT activity than basal or MOS diet at 13 DPI. Challenged increased plasma ceruloplasmin at 4 and 6 DPI, dietary PP or PP+MOS decreased ceruloplasmin compared to basal diet at 6 DPI. Increased ileac activities of inducible nitric oxide synthase (iNOS) and myeloperoxidase (MPO) as well as nitric oxide (NO) production were observed in challenged piglets at 4 and 6 DPI. At 6 DPI, Dietary PP significantly inhibited the elevation of MPO activity and iNOS activity as well as NO production due to challenge. The overall results demonstrated that nutritional supplementation PP improved growth performance and dietary PP or MOS improved feed efficiency in presence of E.coli challenge. Dietary PP or MOS had the potential to improve the antioxidant property, and dietary PP favorably modulated gut mucosa inflammatory response induced by E.coli infection. Dietary combination of PP and MOS did not show effects and even was adverse to growth performance probably due to some unclear interactions between PP and MOS that warranted further research.