# The Effects of Reduced Glutathione on Growth Performance, Intestinal Inflammation, and Gut Microbiota in Immune-Stressed Broiler Chickens

## TL;DR

This study shows that adding 200 mg/kg of reduced glutathione improves growth and gut health in chickens under immune stress.

## Contribution

The study identifies 200 mg/kg of GSH as the optimal dose to mitigate immune stress effects in broiler chickens.

## Key findings

- 200 mg/kg GSH significantly improved growth performance in immune-stressed broilers.
- GSH reduced inflammation and restored gut microbiota balance by inhibiting the TLR4/NF-κB pathway.
- Higher GSH doses increased beneficial bacteria and decreased harmful ones in the gut.

## Abstract

In modern animal production, factors such as environmental stressors, dietary changes, pathogenic microorganisms, and toxins may trigger immune stress reactions. These reactions can severely affect animal growth and development, damage gastrointestinal integrity, and, in extreme cases, even lead to mortality. Reduced glutathione, as an endogenous antioxidant, has detoxification, antioxidant, and immune functions in stressed broiler chickens. This study involved a 21-day feeding experiment to investigate whether GSH could mitigate the negative impacts of lipopolysaccharide LPS-induced immune stress in broiler chickens. Our results demonstrate that dietary supplementation with 200 mg/kg of GSH alleviates LPS-mediated inflammatory damage and increases the levels of beneficial bacteria in the gut microbiota by inhibiting the inflammatory cytokine signaling pathway TLR4/NF-κB.

In intensive farming systems, broilers are exposed to various stressors that trigger immune stress. Reduced glutathione is known to play a crucial role in modulating immune function. This study investigated the effects of different doses of reduced glutathione on the growth performance, intestinal immune function, and gut microbiota of broilers under immune stress. One-day-old broilers were randomly assigned to five groups: group K (control), group L (lipopolysaccharide), and three glutathione supplementation groups, Y1 (50 mg/kg), Y2 (100 mg/kg), and Y3 (200 mg/kg). Each group had four replicates, with 11 broilers per replicate. On days 16, 18, and 20, broilers in groups L and Y1-Y3 received intraperitoneal injections of 0.5 mg/kg of lipopolysaccharide, while group K received an equal volume of saline. On day 16, the average daily weight gain and final body weight of group Y3 were significantly higher than those of groups K and L, whereas on day 21, the average daily weight gain of group Y3 was still significantly higher than that of group L. On day 21 broilers were slaughtered, and samples were collected. In the jejunal mucosa, group Y3 showed significantly reduced levels of IL-2, IL-4, IL-1β, and TNF-α compared to group L. Additionally, group Y3 exhibited reduced relative expression levels of NF-κB, TLR4, IFN-γ, IL-1β, IL-6, IL-4, TNF-α, and IL-2 mRNA; a decreased abundance of Enterococcus, Proteobacteria, and Actinobacteria; and a restored abundance of Ligilactobacillus, Turicibacter, and Firmicutes to normal levels. These findings suggest that 200 mg/kg of reduced glutathione is the optimal dose for improving the gut microbiota composition and mitigating gut damage caused by immune stress by inhibiting the TLR4/NF-κB signaling pathway.