Effects of intramuscular fat on meat quality and its regulation mechanism in Tan sheep

Intramuscular fat (IMF) contributes importantly to various aspects of meat quality, and genetic regulation is an effective pathway to increase IMF content in sheep. In this study, we systematically explored the effect of IMF content on meat quality in Tan sheep, and investigated the potential regulation mechanism of flavor precursors metabolism and IMF divergent deposition. The meat quality measurement analysis showed that IMF are mainly influence meat color, total muscle fiber numbers, and muscle fiber types of Tan sheep. Using a widely-targeted metabolomic method, the flavor precursors were compared between lambs contained different IMF content, and amino acids were found as the main differential flavor precursors. Importantly, the comparison of fatty acid profile revealed that saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) are beneficial for IMF deposition. Furthermore, joint analysis between metabolome and transcriptome indicated that MME is the key gene resulting the reduction of amino acids in lambs with high IMF content; between fatty acid profiles and transcript profiles showed that ADIPOQ, FABP4, PLIN1, PPARGC1A, SLC2A1 accelerate IMF deposition through positive regulation of SFA and MUFA metabolism. The present study is essential for improve IMF content through fatty acids metabolism pathways in sheep.