We compared female and male laying-hen chicks hatched under commercial hatchery conditions versus calm control conditions and found that hatchery stress is associated with widespread changes in DNA methylation in nucleated red blood cells, amplifying sex-specific epigenetic differences and affecting regulatory genomic regions linked to metabolism and immune/signaling functions.
Billions of chickens are hatched in large-scale, industrial hatcheries for egg or meat production every year. This is known to induce a range of negative consequences on chicken welfare throughout life. Here, we explore possible epigenetic mechanisms underlying these effects by analysing blood cell DNA-methylation in one-week old chicks of both sexes that were either hatched in commercial processing units or in a small-scale, calm environment. Using MeDIP on a reduced fraction of the genome, we found that commercial hatching stress induces significant and sex-specific epigenetic modifications in DNA methylation across the genome of laying hen chicks. Through a comprehensive analysis of differentially methylated regions (DMRs) in blood, we identified key genes and regulatory pathways, including those involved in lipid metabolism, immune response, and cell signaling, that are distinctly affected by hatching stress. The patterns of hypermethylation and hypomethylation observed in both sexes suggest a dynamic and adaptive epigenetic response to stress, with females exhibiting greater methylation changes than males. The results suggest a possible mechanism underlying the previously found extensive effects of commercial hatchery processing on the welfare of laying hens and provides valuable insights into the potential mechanisms underlying stress resilience and vulnerability, with implications for poultry management and welfare.
Billions of chickens are hatched in large-scale, industrial hatcheries for egg or meat production every year. This is known to induce a range of negative consequences on chicken welfare throughout life. Here, we explore possible epigenetic mechanisms underlying these effects by analysing blood cell DNA-methylation in one-week old chicks of both sexes that were either hatched in commercial processing units or in a small-scale, calm environment. Using MeDIP on a reduced fraction of the genome, we found that commercial hatching stress induces significant and sex-specific epigenetic modifications in DNA methylation across the genome of laying hen chicks. Through a comprehensive analysis of differentially methylated regions (DMRs) in blood, we identified key genes and regulatory pathways, including those involved in lipid metabolism, immune response, and cell signaling, that are distinctly affected by hatching stress. The patterns of hypermethylation and hypomethylation observed in both sexes suggest a dynamic and adaptive epigenetic response to stress, with females exhibiting greater methylation changes than males. The results suggest a possible mechanism underlying the previously found extensive effects of commercial hatchery processing on the welfare of laying hens and provides valuable insights into the potential mechanisms underlying stress resilience and vulnerability, with implications for poultry management and welfare.
Fpertille