Effects of glucose oxidase on growth performance, clinical symptoms, serum parameters, and intestinal health in piglets challenged by enterotoxigenic Escherichia coli

Abstract

Glucose oxidase (GOD) could benefit intestinal health and growth performance in animals. However, it is unknown whether GOD can protect piglets against bacterial challenge. This study aimed to evaluate the protective effects of GOD on growth performance, clinical symptoms, serum parameters, and intestinal health in piglets challenged by enterotoxigenic Escherichia coli (ETEC). A total of 44 male weaned piglets around 38 days old were divided into four groups (11 replicates/group): negative control (NC), positive control (PC), CS group (PC piglets +40 g/t colistin sulfate), and GOD group (PC piglets +200 g/t GOD). All piglets except those in NC were challenged with ETEC (E. coli K88) on the 11th day of the experiment. Parameter analysis was performed on the 21st day of the experiment. The results showed that the ETEC challenge elevated (p < 0.05) the rectal temperature and fecal score of piglets at certain time-points post-challenge, reduced (p < 0.05) serum glucose and IgG levels but increased (p < 0.05) serum alanine aminotransferase activity, as well as caused (p < 0.05) intestinal morphology impairment and inflammation. Supplemental GOD could replace CS to reverse (p < 0.05) the above changes and tended to increase (p = 0.099) average daily gain during the ETEC challenge. Besides, GOD addition reversed ETEC-induced losses (p < 0.05) in several beneficial bacteria (e.g., Lactobacillus salivarius) along with increases (p < 0.05) in certain harmful bacteria (e.g., Enterobacteriaceae and Escherichia/Shigella). Functional prediction of gut microbiota revealed that ETEC-induced upregulations (p < 0.05) of certain pathogenicity-related pathways (e.g., bacterial invasion of epithelial cells and shigellosis) were blocked by GOD addition, which also normalized the observed downregulations (p < 0.05) of bacterial pathways related to the metabolism of sugars, functional amino acids, nucleobases, and bile acids in challenged piglets. Collectively, GOD could be used as a potential antibiotic alternative to improve growth and serum parameters, as well as attenuate clinical symptoms and intestinal disruption in ETEC-challenged piglets, which could be associated with its ability to mitigate gut microbiota dysbiosis. Our findings provided evidence for the usage of GOD as an approach to restrict ETEC infection in pigs.

Keywords: antibiotic alternative; bacterial infection; body weight gain; gut microbiota; immune status; intestinal disruption; weaned piglet.

Figure 1

Effect of dietary treatments on the relative mRNA expression of intestinal inflammatory cytokines in piglets challenged by enterotoxigenic Escherichia coli (ETEC). ^a,bValues with different superscripts differ significantly (p < 0.05). NC, negative control (piglets were free of the challenge); PC, positive control (piglets were challenged with ETEC on the 11th day of the experiment); CS, PC piglets supplemented with 40 g/t colistin sulfate; and GOD, PC piglets supplemented with 200 g/t glucose oxidase. Samples were analyzed on the 21st day of the experiment.

Figure 2

Partial least squares discriminant analysis (PLS-DA) diversity of piglet gut microbiota among groups. NC, negative control (piglets were free of the challenge); PC, positive control (piglets were challenged with enterotoxigenic E. coli on the 11th day of the experiment); and GOD, PC piglets supplemented with 200 g/t glucose oxidase. Samples were analyzed on the 21st day of the experiment.

Figure 3

Gut microbial composition of piglets. (A) at phylum level; (B) at class level; (C) at order level; (D) at family level; (E) at genus level. NC, negative control (piglets were free of the challenge); PC, positive control (piglets were challenged with enterotoxigenic E. coli on the 11th day of the experiment); and GOD, PC piglets supplemented with 200 g/t glucose oxidase. Samples were analyzed on the 21st day of the experiment.