Abstract: Meat flavor is an important trait in the evaluation of meat pigeon genetic resources and the breeding of high ? quality meat pigeons，while lipid deposition and fatty acid composition in the pectoral muscle are key determinants of flavor development. To investigate the dynamic patterns of lipid deposition in the pectoral muscle of Shiqi squabs and the potential regulatory roles of positively selected genes involved in lipid metabolism，Shiqi pigeons were sampled at 1，7，14，21，28，and 35 days of age. Pectoral muscle samples were collected after slaughter，and lipid droplet distribution，fatty acid composition，and the expression profiles of positively selected lipid metabolism? related genes were analyzed using Oil Red O staining，gas chromatography，and quantitative real?time PCR（qPCR）， respectively. The results showed age?dependent，stage?specific changes in lipid droplet distribution in the pectoral muscle. Compared with that at 1 day of age，the lipid droplet area initially decreased and subsequently increased. At 35 days of age，the lipid droplet area was significantly greater than that at 1 day of age（P<0.05） and highly significantly greater than those at 7，14，21，and 28 days of age（P<0.01）. Saturated fatty acids constituted the largest proportion of fatty acids in the pectoral muscle，whereas the proportion of unsaturated fatty acids gradually increased with age. From 1 to 14 days of age，PPARα，which is involved in fatty acid oxidation，and its downstream genes， including ECHS1 and HADH，were highly expressed. After 14 days of age，the expression of genes involved in fatty acid synthesis and transport，including LPIN1，ACSS3，and APOB，was upregulated，whereas the expression of the endocytosis?related gene AP2M1 was downregulated. Correlation analysis showed that oxidative metabolism?related genes，such as ACOX2 and ACADSB，were generally significantly negatively correlated with short? and medium?chain saturated fatty acids（C6：0，C8：0，C10：0，and C12：0；r=-0.81 to -0.99，P<0.05）. In contrast，genes such as ACOX3 and HADH were significantly positively correlated with long?chain saturated fatty acids（C17：0，C18：0，C20： 0，and C24：0）and several polyunsaturated fatty acids（C18：2n?6t，C18：3n?3，C20：3n?6，and C22：6n?3；r=0.83– 1.00，P<0.05）. Among genes involved in anabolic metabolism，LPIN1 was highly significantly positively correlated with cis?oleic acid（C18：1n?9 cis；r=0.94，P<0.01），while SOAT1 was highly significantly positively correlated with myristic acid（C14：0）and docosadienoic acid（C22：2n?6；r=0.94 and 1.00，respectively；P<0.01）. In conclusion， lipid deposition and fatty acid composition in the pectoral muscle of Shiqi squabs exhibit distinct temporal changes during growth and development. Positively selected genes related to lipid metabolism may regulate pectoral muscle lipid deposition by modulating fatty acid oxidation，synthesis，and transport.

Key words: Shiqi squab；Pectoral muscle；Lipid deposition；Fatty acid composition；Positive selection gene

摘要： 肉质风味是肉鸽品种资源评价和优质肉鸽选育的重要性状，而胸肌脂质沉积和脂 肪酸组成是影响肉质风味形成的关键因素。为探究石岐乳鸽胸肌脂质沉积动态变化规律及脂 质代谢相关正选择基因的潜在调控作用，该研究选取1、7、14、21、28和35日龄石岐乳鸽，屠宰 后采集胸肌样品，通过油红O染色、气相色谱分析及实时荧光定量PCR（qPCR），分析脂滴分 布、脂肪酸组成及脂质代谢相关正选择基因表达特征。结果表明，石岐鸽胸肌脂滴分布随日龄 增长呈现阶段性变化，相较于1日龄，石岐鸽胸肌脂滴面积呈先下降后上升的趋势，其中35日 龄乳鸽胸肌脂滴面积显著高于1日龄（P<0.05），极显著高于7、14、21和28天（P<0.01）。胸肌脂 肪酸以饱和脂肪酸占比最高，随日龄增长不饱和脂肪酸比例逐渐增加。1－14日龄，与脂肪酸 氧化相关的PPARα 及其下游的ECHS1、HADH等相关基因呈现高表达。14日龄以后，与脂肪 酸合成转运相关的LPIN1、ACSS3和APOB等基因表达上调，而与细胞内吞相关基因AP2M1表 达下调。相关性结果表明，氧化代谢相关基因如ACOX2 和ACADSB 与短链及中链饱和脂肪酸 （C6：0、C8：0、C10：0、C12：0）普遍呈显著负相关（r=-0.81－-0.99，P<0.05），而ACOX3 和HADH 等基因与长链饱和脂肪酸（C17：0、C18：0、C20：0、C24：0）及部分多不饱和脂肪酸（C18：2n?6t、 C18：3n?3、C20：3n?6、C22：6n?3）呈显著正相关（r=0.83－1.00，P<0.05）。合成代谢相关基因如 LPIN1 与顺式油酸（C18：1n9cis）呈极显著正相关（r=0.94，P<0.01），SOAT1与肉豆蔻酸（C14：0） 及二十二碳二烯酸（C22：2n?6）呈极显著正相关（r=0.94、1.00，P<0.01）。综上，石岐乳鸽胸肌脂 质沉积和脂肪酸组成在生长发育过程中呈现明显时序性变化，脂质代谢相关正选择基因可能 通过调控脂肪酸氧化、合成与转运过程参与胸肌脂质沉积调控。

关键词: 石岐乳鸽；胸肌；脂质沉积；脂肪酸组成；正选择基因