Effect of plant extract on growth performance, antioxidant defense system and gut health in weanling pigs infected with Escherichia coli

This study was conducted to evaluate the efficacy of plant extract on growth performance, systemic antioxidant defense and gut health in weanling pigs infected with Escherichia coli virus. One hundred and forty-four weanling pigs (Stambo HBI Dalland 40) (24-d-old) were homogenously allocated to 8 treatments according to body weight and sex (6 replicates with 3 pigs per treatment). Treatments followed a 2 × 2 × 2 factorial design with 2 types of water treatment (control and plant extract (PE) addition), 2 kinds of feed regimen (ad libitum and restricted) and 2 levels of E. coli virus (with and without). PE was supplemented to pigs from 8 PM to 8 AM through drinking water (the amount of the product was estimated at 0.0728 ml/pig/day) every day. After 9 d of 35-d period of drinking the treatments, half of the pigs in each water treatment received an orally inoculation of 4 ml solution containing 109cfu/ml of the virulent E. coli 0149: F4 (K88)-positive strain. Plasma samples were collected at 0, 6, 19 and 35 days of the trial and ileac mucosa samples were prepared at 35 d for antioxidative property and intestinal inflammatory responsive parameters. Supplementation of PE significantly increased average daily gain (ADG) from 28 to 35d, and decreased feed conversion ratio (FCR) from 7 to 14 d, from 28 to 35 d and from 0 to 35 d. Restricted the feed induced to animals have lower ADG from 28 to 35d, ADFI from 7 to 14d and from 14 to 21 d than piglets who were fed as ad libitum, but animals had high FCR in restrictive groups from 21 to 28 days of the trial. After E.coli challenge, low ADG from 14 to 21d and ADFI from 28 to 35 and the whole phase were observed compared to non-challenge animals, and also challenge groups had higher FCR than non-challenge animals from 7 to 14 d. There were significant interactions among treatment, regime and challenge on bacterial counts of Lactobacilli at 14 d, Enterobacteriaceae at 35 d and E.coli at 14 d. Addition of PE significantly decreased the bacterial counts of Enterobacteriaceae and E.coli at 35d of the trial. Fed animals by restrictive way increased the bacterial counts of Lactobacilli, Enterobacteriaceae and E.coli at 35 d of the trial. Injection of E.coli virus induced to high bacteria counts of Enterobacteriaceae at 35 d and E.coli at 21 d. The significant interactions between treatment and challenge on faecal score were observed at 28 and 35 d. Supplementation of PE decreased the faecal score throughout the trial. Pigs after injection of E. coli virus had high faecal scores at 14, 21, 28 and 35 d compared to without challenge. There was significant interaction between treatment and challenge on T-AOC at 19 days of the trial. PE treatment had low GSH-Px at day 6 compared to Control group. Restrictively fed animals increased SOD at 35d. Challenge induced to the significant increase of GSH-Px at 19d and MDA at 35d. After infection of E. coli, there were significant interactions among treatment, regime and challenge on HGB at 35 d and HCT at 19d. Supplementation of PE increased the concentration and ratio of Eosinophils at 19 days of the trial. Restrictive feeding induced to significant increase of HGB, HCT, RDW-SD, RDW-CV, Monocytes, ratio of Monocytes and Eosinophilsat 35 days of the trial. Injection of E.coli increased WBS, RDW-CV, Neutrophils, Basophils, ratio of Eosinophils and Basophils at 19 d, meanwhile, it also increased WBS, MCHC, PLT, Neutrophils, Lymphocytes, Monocytes and Basophils at 35d. At slaughtering, there was no significant interaction on inflammatory parameters between challenge and treatment in the intestinal mucosa of restrictive feeding animals. While challenge induced to significant high MPO. Regard to histomorphometry of ileum in piglets fed restricted diet, supplementation of PE in combination with E. coli inoculation had highest crypt depth compared with others groups, and control group in combination with E. coli injection had highest Macrophages number. Briefly, supplementation of PE improved growth performance and faeces population in the face of E. coli challenge.