Abstract: Intramuscular fat is an important factor affecting the quality of meat, and its content directly affects the taste and flavor of meat. At present, the determination of intramuscular fat is most commonly used in marble score, soxhlet extraction and ultrasonic detection. The process of intramuscular fat formation and deposition involves various molecules and signaling pathways, complex and highly coordinated expression regulation, including key genes, enzymes, signaling pathways, and non-coding RNAs. Intramuscular fat content has an impact on multiple meat quality, including pH value, tenderness, juiciness, shear force, etc., and is affected by many factors. This paper expounded the intramuscular fat of livestock and poultry animals from different angles of the determination method, molecular regulation mechanism and the effect on meat quality, aiming to provide valuable reference for the intramuscular fat of animals breeding.

Key words: intramuscular fat deposition, the determination of intramuscular fat, molecular mechanism, non-coding RNAs