Transcriptome profiling of the liver and pectoralis major muscle in slow-growing chickens under an organic raising system

The strategy to improve the competitiveness of smallholder farmers and to serve highly nutritious meat for consumers is the major goal of Korat chicken (KRC) production in Thailand. Organic KRC meat contains high n-3 polyunsaturated fatty acids (PUFA) and docosahexaenoic acid (DHA), which have a wide range of health-related benefits. However, limited scientific investigations have been conducted on the modulations of PUFA and DHA in KRC. In this study, we compared two rearing systems, conventional (CO) and organic raising (OR) systems, and their effects on global gene expression related to the accumulation of n-3 PUFA and DHA in the liver and pectoralis major muscle were investigated by using RNA-sequencing (RNA-seq). Total RNA was isolated from the liver and pectoralis major muscle of male KRC in each treatment group (n = 5). RNA-seq revealed a total of 561 and 361 differentially expressed genes between CO and OR groups identified in the liver and pectoralis major muscle, respectively. ELOVL fatty acid elongase 2 (ELOVL2) may activate n-3 PUFAs synthesis via the fatty acid elongation pathway. The KRC seems suitable to raise under the organic raising system, since it improved lipid metabolism and immune response in the liver. However, thermal environmental management and growth performance need to be considered. ELOVL2 can use as a gene marker for n-3 PUFAs synthesis in the liver. This study provides a genetic basis for future breeding strategies to improve the genetics of slow-growing chickens to fit with an organic raising system. Overall design: Liver and pectoralis major muscle tissues were collected from chicken in conventional (n=5) and organic (n=5) raising systems and differentially expressed genes were identified using RNA-sequencing.