# Differential Expression of Hypothalamic Genes in Laying Hens Housed in Caged and Cage-Free Systems Under Commercial Conditions in the Tropics

## TL;DR

This study explores how different housing systems affect gene expression in laying hens, revealing impacts on stress and metabolism.

## Contribution

The study introduces transcriptomic analysis as a novel tool to assess animal welfare in commercial egg production systems.

## Key findings

- Housing conditions significantly influence hypothalamic gene expression in laying hens.
- Key pathways affected include hormonal activity, cytoskeletal structure, and neuropeptide signaling.
- These changes impact feed intake, metabolism, and stress responses in hens.

## Abstract

Growing public concern regarding animal welfare and food quality in intensive production systems has increased research interest in the welfare of farm animals, especially laying hens. Welfare evaluations have traditionally been based on the Five Freedoms framework and physiological and behavioral stress indicators, such as corticosterone levels; however, inconsistencies in these measures underscore the need for complementary assessment tools. In this study, a transcriptomic approach was used to investigate gene expression in laying hens housed in two different egg production systems as an exploratory study. Hypothalamic gene expression profiles were compared between hens raised in conventional cages and those raised in cage-free systems under commercial conditions. The results revealed that housing conditions associated with each production system significantly influence hypothalamic gene expression. Pivotal differences were found in pathways related to hormonal activity, cytoskeletal structure, and neuropeptide hormone signaling. These pathways are involved in the regulation of feed intake, metabolism, hormonal balance, and stress responses, highlighting the impact of housing systems on the physiological and molecular processes associated with animal welfare.

Increasing concerns over animal welfare and food quality in intensive animal production systems have motivated enhanced scientific investigation into farm animal welfare, particularly laying hens. Traditional welfare assessments have relied mainly on the Five Freedoms framework and stress indicators such as corticosterone levels and behavioral responses; however, the reliability of these measurements can vary, necessitating the exploration of alternative methods. This research utilizes transcriptomic methodology to gain a deeper understanding of the genetic mechanisms influencing animal welfare in egg production systems. This study examined the hypothalamic transcriptome from hens reared under two distinct egg production systems: conventional cages and cage-free environments. Our findings indicated that the housing conditions associated with the egg production system can modulate genetic expression within the hypothalamus. The production systems affected pathways related to hormone activity, cytoskeletal organization, and neuropeptide hormone function, influencing feed intake, hormone regulation, metabolism, and stress response.