# Dietary Glucosamine: Effects and Mechanisms in Relation to Production Performance, Eggshell Quality, and Liver Health of Aged Laying Hens

## TL;DR

This study shows that dietary glucosamine improves eggshell quality and liver health in aged laying hens by regulating metabolism and inflammation.

## Contribution

The study reveals the molecular mechanisms by which glucosamine improves production performance and liver health in aged laying hens.

## Key findings

- Glucosamine improves laying rate, eggshell strength, and thickness in aged hens.
- Glucosamine reduces hepatic steatosis and serum markers of liver damage and inflammation.
- Glucosamine upregulates fatty acid breakdown and antioxidant genes while downregulating lipid synthesis and inflammatory genes.

## Abstract

In response to common issues related to poor liver health and decreased eggshell quality in elderly laying hens, this study systematically evaluated the therapeutic effect of glucosamine (GS). The results indicate that GS can significantly improve the laying rate, eggshell quality, and liver health of elderly laying hens. The biological mechanism behind this is that GS upregulates the expression of fatty acid breakdown, antioxidant, and eggshell matrix protein genes and downregulates the expression of lipid synthesis and inflammatory genes in the liver. In summary, this study systematically elucidated the effects and molecular mechanisms of GS and explored its role in improving the production performance and liver health of elderly laying hens, providing potential nutritional strategies and a scientific basis to improve the liver health, eggshell quality, and breeding efficiency of elderly laying hens.

The aim of this study is to investigate the effects and mechanisms of GS in relation to the production performance, eggshell quality, and liver health of aged laying hens. A total of 144 elderly laying hens were randomly divided into a control group, a 0.15% GS group, and a 0.35% GS group and fed for 4 weeks. The experimental results revealed that GS can significantly improve the laying rate, eggshell strength, and eggshell thickness of aged laying hens and reduce the feed-to-egg ratio (p < 0.05). Specifically, 0.35% GS can alleviate symptoms of hepatic steatosis; significantly reduce the levels of AST, TG, and MDA in serum; and increase the levels of ALB and GSH-Px (p < 0.05). The sequencing results demonstrated that GS significantly upregulated the expression of fatty acid breakdown and antioxidant genes, such as PPARA, ACOX1, GSTT1, and CAT, in the liver, while downregulating the expression of fatty acid synthesis and inflammatory genes such as PPARG, FASN, TGFBR2, and TNF-α (p < 0.05). Meanwhile, GS also increased the expression of uterine eggshell matrix protein genes (p < 0.05). In summary, GS improves liver health by regulating fatty acid metabolism, inflammation, and antioxidant pathways and enhances eggshell quality by promoting eggshell matrix protein synthesis.