Jejunal Transcriptomic Profiling for Differences in Feed Conversion Ratio in Slow-Growing Chickens

Slow-growing Korat chicken (KR) is an alternative to broiler chickens that has been used as a national tool to support smallholder farmers due to a higher selling price of KR meat. However, the individual variability of feed efficiency (FE) within a KR stockbreeding results in a lack of competitiveness. Therefore, improvement of FE of KR is of major importance to improve the profitability of livestock production enterprises. Here, we selected two groups of KR with divergent feed conversion ratios (FCR). We performed RNA-sequencing in order to profile KR jejunal transcriptome and to identify the transcriptional variations and biological pathways implied in response to divergent FCR. The biological pathways involved were revealed by enrichment of the Gene Ontology (GO) terms, and the Kyoto Encyclopedia of Gene and Genome (KEGG) pathways. The results showed that main pathways involved in KR FCR divergence were related to immune response, glutathione metabolism, vitamin transport and metabolism, lipid metabolism, and maturation, development and growth. This is the first study to investigate the molecular genetic mechanisms affecting the FCR values in jejunum of slow-growing chicken. This study will be useful in the line-breeding programs for slow growing chickens to improve FE in the stockbreeding and its profitability. Overall design: Jejunal samples of six KR were collected with extremely low FCR (n = 3) and high FCR (n = 3) and differentially expressed genes were identifiled using RNA-sequencing.慢生长呵叻鸡（Korat chicken, KR）是肉鸡的替代养殖品种，因其肉质售价更高，已被用作扶持小农户养殖的国家级支撑品种。然而，呵叻鸡养殖种群内个体间饲料效率（feed efficiency, FE）存在显著差异，导致其市场竞争力不足。因此，提升呵叻鸡的饲料效率对提高畜牧生产企业的盈利能力具有重要意义。本研究选取了饲料转化率（feed conversion ratio, FCR）存在显著差异的两组呵叻鸡，通过RNA测序（RNA-sequencing）技术对其空肠转录组进行测序分析，以鉴定不同FCR组间的转录变异及响应差异的生物学通路。本研究通过基因本体（Gene Ontology, GO）功能富集分析与京都基因与基因组百科全书（Kyoto Encyclopedia of Genes and Genomes, KEGG）通路富集分析，揭示了与呵叻鸡FCR差异相关的生物学通路。研究结果显示，与呵叻鸡FCR差异相关的主要生物学通路涉及免疫应答、谷胱甘肽代谢、维生素转运与代谢、脂质代谢，以及细胞成熟、发育与生长过程。本研究首次针对慢生长鸡空肠组织中影响FCR的分子遗传机制展开探究，可为慢生长鸡的品系选育工作提供理论参考，有助于提升养殖群体的饲料效率并改善其养殖盈利能力。实验设计：选取6只呵叻鸡的空肠组织样本，其中3只为极低FCR组（n=3），3只为极高FCR组（n=3），通过RNA测序技术鉴定两组间的差异表达基因。