# Transcriptomic Profiling Identifies Key Genes and ERBB Signaling Pathway Associated with Aggressive Behavior in Muscovy Ducks (Cairina moschata)

## TL;DR

This study identifies genes and the ERBB signaling pathway linked to aggressive behavior in Muscovy ducks, offering insights for improving welfare in farming.

## Contribution

The study reveals 26 overlapping differentially expressed genes and the ERBB pathway's role in aggression in Muscovy ducks.

## Key findings

- 626 and 649 differentially expressed genes were identified in aggressor and victim ducks, respectively.
- 69 candidate genes were enriched in behavior and sensory perception of pain, and the ERBB signaling pathway.
- qRT-PCR validated 14 key genes, confirming the transcriptomic data's reliability.

## Abstract

Aggressive behavior severely impairs animal welfare and causes production losses in intensive Muscovy duck (Cairina moschata) farming. To elucidate its molecular mechanisms, we performed hypothalamic transcriptomic profiling of 120 60-day-old female ducks stratified via 24-h continuous monitoring into three groups: aggressor, victim, and control. Illumina HiSeq 2500 sequencing and differential expression analysis identified 626 DEGs in the aggressor group and 649 in the victim group vs. the control group, with 26 overlapping DEGs linked to aggression. Integrative GO and KEGG analyses revealed 69 candidate genes significantly enriched in the behavior (GO:0007610) and sensory perception of pain (GO:0019233) terms, as well as the evolutionarily conserved ERBB signaling pathway (map04012). qRT-PCR validation of 14 key genes (e.g., NPY, ERBB4) confirmed transcriptomic data reliability. These findings provide novel insights into the genetic basis of duck aggression and a framework for targeted mitigation strategies in intensive farming.

Aggressive behavior in Muscovy ducks (Cairna moschata) has become a predominant concern in intensive farming systems, leading to reduced animal welfare and production losses. To unravel the molecular mechanisms underlying this behavior, transcriptomic profiling was performed on the hypothalamus, a key regulatory hub for aggressive responses. A total of 120 healthy 60-day-old female Muscovy ducks were continuously monitored for 24 h/day over one month using Media Recorder 2.0 software. Based on instantaneous and continuous behavioral observations, the ducks were categorized into three groups: aggressor (Experimental group I, actively attacking conspecifics), victim (Experimental group II, receiving aggression), and non-aggressive (Control group, no aggressive interactions). Hypothalamic tissues were collected from each group (n = 4 per group) for Illumina HiSeq 2000 high-throughput transcriptome sequencing. Functional annotation and enrichment analysis of differentially expressed genes (DEGs) were performed using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases, followed by quantitative real-time PCR (qRT-PCR) validation. GO analysis identified 626 DEGs in the aggressor group and 649 DEGs in the victim group compared to the control group, with 26 DEGs directly involved in aggressive behavior regulation. Integration of GO and KEGG annotations revealed 69 candidate genes associated with aggressive behavior, enriched in two GO terms (behavior [GO:0007610] and sensory perception of pain [GO:0019233]) and the ERBB signaling pathway (map04012). qRT-PCR validation of 14 randomly selected candidate genes (e.g., NPY, ERBB4, MAPK9, PRDM12) confirmed that their expression patterns were consistent with transcriptomic data, verifying the reliability of the sequencing results. These findings provide novel insights into the molecular genetic basis of aggressive behavior in Muscovy ducks and lay a foundation for developing targeted strategies to mitigate aggression in intensive farming systems.