Liver Transcriptome Response to Hyperthermia Stress in Three Distinct Chicken Lines

High ambient temperatures cause stress in poultry, especially broiler lines, which are genetically selected for rapid muscle growth. RNA-seq technology provides powerful insights into environmental response of a highly metabolic tissue, the liver. We investigated the effects of acute (3h, 35°) and chronic (7d of 35° for 7h/d) heat stress on the liver transcriptome of 3wk-old chicks of a heat-susceptible broiler line, the heat-resistant Fayoumi and an advanced intercross line (AIL). Transcriptome sequencing of 48 male chickens using Illumina HiSeq 2500 technology yielded an average of 3.4 million, 100-base -pair single-end, reads per sample. There were 8 times more (N=627) differentially expressed genes (DEGs) in the broiler acute-heat group compared to control (25°) samples (FDR<0.05), than in Fayoumi (N=78). Contrasting genetic lines under similar heat treatments, the highest number of DEGs appeared between Fayoumi and Broiler. DEGs number suggests that acute heat stress has greater impact on liver metabolism than chronic heat in broiler and AIL, but not Fayoumi. Ingenuity Pathway Analysis revealed 7 common overrepresented functions, related to liver metabolism and signaling, including Fatty Acid β-oxidation I, and Fatty Acid Activation were detected in comparison analysis of 6 heat-control contrasts. “Lipid Metabolism” and “Organismal Injury, Abnormalities and Inflammatory Response” were the two highest ranking networks in all genetic lines. This study extends our understanding of the liver transcriptome response to different heat treatments in novel genetic chicken lines and provides fundamental information needed to breed birds more resilient to climate change.

Support: USDA-NIFA-AFRI grant and Hatch project #5358