145 Dose-Response and Functional Roles of Zinc Glycinate on Growth and Intestinal Health of Nursery Pigs Challenged with F18+Escherichia Coli

Abstract

Abstract This study was to evaluate dose-response and supplemental effects of zinc glycinate (ZnGly) on growth and intestinal health of nursery pigs challenged with F18+Escherichia coli. Nursery pigs (n = 40; BW = 6.5 ± 0.5 kg) were allotted to 5 treatments in a randomized complete block design with BW and sex as blocks: 1) NC: no-challenge/no-supplement; (2) PC: F18+E. coli challenge/no-supplement; (3 to 5) F18+E. coli challenge/supplementations of ZnGly at 400, 800, and 1,200 mg/kg. On d 7, challenged groups were orally inoculated with F18+E. coli at 6 × 109 CFU/mL, whereas NC received saline solution. Pigs were fed for 28 d based on 2 phases (Phase 1: 14 d and phase 2: 14 d), and experimental diets were formulated to meet or exceed nutrient requirements suggested by NRC (2012). Pigs were euthanized on d 28 to collect tissues to evaluate TNF-α, IL-8, malondialdehyde, protein carbonyl, gene expression of Zn transporters, and mucosa-associated microbiota in the jejunum. Data were analyzed using contrasts in the MIXED procedure of SAS. The E. coli challenge tended to reduce (P = 0.065) ADG (308 to 244 g/d) and increase (P < 0.05) fecal score (3.2 to 4.1) of the pigs during the first week of post-challenge. Supplementation of ZnGly from 0 to 1,200 mg/kg linearly (P = 0.092) increased G:F (0.69 to 0.81) during phase 1 and decreased (P <0.05) fecal score (4.1 to 3.5) of the pigs during the first week of post-challenge. Supplementation of ZnGly from 0 to 1,200 mg/kg had quadratic effects on TNF-α (P = 0.065; minimum 1.51 pg/mg at 405 mg/kg of ZnGly), IL-8 (P = 0.093; minimum 0.53 ng/mg at 494 mg/kg), and protein carbonyl (P = 0.054; minimum 2.30 pg/mg at 675 mg/kg) and linearly increased mRNA expressions of (P = 0.057) ZIP4 (0.69 to 1.03) and (P = 0.075) ZnT5 (0.92 to 1.22) in the jejunum of the pigs. Supplementation of ZnGly from 0 to 1,200 mg/kg tended to linearly decrease (P = 0.065) Chao1 index (150.6 to 144.6) and linearly increased (P < 0.05) relative abundance of Actinobacteria (13.10 to 16.26%) and had quadratic effects (P < 0.05) on the relative abundance of Cyanobacteria (minimum 0.67 % at 625 mg/kg) and Proteobacteria (minimum 45.6% at 735 mg/kg) at the phylum level with Enterobacteriaceae (minimum 4.79% at 660 mg/kg) at family level in jejunal mucosa-associated microbiota of the pigs. In conclusion, supplementation of ZnGly at a range of 400 to 675 mg/kg could reduce the negative impacts of F18+E. coli on growth performance and diarrhea of nursery pigs. These positive changes are related to reducing jejunal inflammation and oxidative stress by enhancing jejunal Zn absorption with positive changes in jejunal mucosa-associated microbiota in the pigs.