Zinc oxide enriched peat influence Escherichia coli infection related diarrhea, growth rates, serum and tissue zinc levels in Norwegian piglets around weaning: five case herd trials

Microencapsulated essential oils alleviate diarrhea in weaned piglets by modulating the intestinal microbial barrier as well as not inducing antibiotic resistance: a field research

Microencapsulated essential oils (MEO)have been used as antibiotic alternatives that can be applied to alleviate diarrhea in weaning piglet. We examined a large group of weaned piglets and incorporated essential oil containing thymol (2%), carvacrol (5%) and cinnamaldehyde (3%) in the feed of weaned piglets on an intensive production farm. The piglets were divided into four groups; Control (no additions) and chlortetracycline (Chl), essential oil (EO) and microencapsulated essential oil (MEO) were fed ad libitum over a 28-day trial period. We found MEO significantly reduced the incidence of diarrhea in the piglets that was also accompanied by increased average daily weight gains from days 14-28 (p < 0.05). MEO enhanced the antioxidant capacity in the piglets and serum total antioxidant capacity (T-AOC) and glutathione peroxidase (GSH-px) levels were significantly increased (p < 0.05). MEO also significantly reduced expression of genes related to ileal inflammation (IL-6, TNF-α and TGF-β1) (p < 0.05) and significantly (p < 0.05) increased in sIgA antibody levels. MEO influenced the composition of the intestinal microbiome and reduced Bacteroidota (p < 0.05) and thus altered the Firmicutes/Bacteroidota ratio. However, none of the treatments produced significant changes in the most common tetracycline resistance genes (p > 0.05). Metagenomic analysis indicated that MEO impacted DNA expression, virulence factors, antioxidant activity and antimicrobial activity. Metabolomic analysis of the intestinal content also indicated that MEO impacted tyrosine metabolism and primary bile acid biosynthesis suggesting improved intestinal health and nutrient absorption. This study paves the way for further research into the development and optimization of MEO-based interventions aimed at improving piglet health and performance while also providing a reference for reducing reliance on antibiotics in animal agriculture.

Is Oral Vaccination against Escherichia coli Influenced by Zinc Oxide?

BACKGROUND

Although zinc oxide has been banned at therapeutic doses in the EU, its use is still legal in most countries with industrial pig farming. This compound has been shown to be very effective in preventing E. coli-related diseases. However, another strategy used to control this pathogen is vaccination, administered parenterally or orally. Oral vaccines contain live strains, with F4 and F18 binding factors. Since zinc oxide prevents E. coli adhesion, it is hypothesised that its presence at therapeutic doses (2500 ppm) may alter the immune response and the protection of intestinal integrity derived from the vaccination of animals.

METHODS

A group of piglets were orally vaccinated at weaning and divided into two subgroups; one group was fed a feed containing 2500 ppm zinc oxide (V + ZnO) for the first 15 days post-vaccination (dpv) and the other was not (V). Faeces were sampled from the animals at 6, 8, 11, 13, and 15 dpv. Unvaccinated animals without ZnO in their feed (Neg) were sampled simultaneously and, on day 15 post-vaccination, were also compared with a group of unvaccinated animals with ZnO in their feed (ZnO).

RESULTS

Differences were found in E. coli excretion, with less quantification in the V + ZnO group, and a significant increase in secretory IgA in the V group at 8 dpv, which later equalised with that of the V + ZnO group. There was also some difference in IFNα, IFNγ, IL1α, ILβ, and TNFα gene expression when comparing both vaccinated groups (p < 0.05). However, there was no difference in gene expression for the tight junction (TJ) proteins responsible for intestinal integrity.

CONCLUSIONS

Although some differences in the excretion of the vaccine strain were found when comparing both vaccinated groups, there are no remarkable differences in immune stimulation or soluble IgA production when comparing animals orally vaccinated against E. coli in combination with the presence or absence of ZnO in their feed. We can conclude that the immune response produced is very similar in both groups.

Zinc uptake system ZnuACB is essential for maintaining pathogenic phenotype of F4ac+ enterotoxigenic E. coli (ETEC) under a zinc restricted environment

Zinc is the second trace element of living organisms after iron. Given its crucial importance, mammalian hosts restrict the bioavailability of Zinc ions (Zn²⁺) to bacterial pathogens. As a countermeasure, pathogens utilize high affinity Zn²⁺ transporters, such as ZnuACB to compete with the host for zinc. It is essential for bacteria to maintain zinc homeostasis and thus maintain their physiology and pathogenesis. In an attempt to uncover the zinc transporter in F4⁺ enterotoxigenic E. coli (ETEC) C83902, we analyzed two RNA-seq data sets of bacteria samples when different zinc treatments (restriction or abundance) were applied. Considering data revealing that the high affinity zinc uptake system ZnuACB acts as the main transporter in ETEC C83902 to resist zinc deficiency, we deleted znuACB genes to study the role of them in ETEC C83902. The deletion of znuACB genes results in growth perturbation and a sharp decrease in the ability of biofilm formation and adhesion of bacteria in vitro. Taking the data together, this study demonstrates that the ZnuACB system is required for ETEC C83902 to acquire zinc, which highly contributes to ETEC pathogenicity as well.