Influence of slaughter age on meat quality, metabolite and volatile organic compound changes in Lueyang black-bone chickens

Abstract

With the increasing demand for high-quality poultry products, optimizing slaughter age is crucial for balancing meat yield, texture, and flavor. Lueyang black-bone chicken is a slow growing strain and prized for its superior nutritional value, yet the influence of age on meat quality and flavor profiles remains insufficiently characterized. This study systematically evaluated the effects of slaughter age (4,6, and 8 months) on carcass traits, metabolites, and volatile organic compound profiles in breast and leg muscles. Key findings revealed that the carcass yield of Lueyang black-bone chickens tended to stabilize at 6 months of age, while shear force as a key indicator of meat tenderness increased progressively with age. Metabolomic analysis demonstrated that younger chickens (4 months) exhibited higher levels of bioactive peptides (Asp-Ile-Glu, Leu-Pro-Thr, Ile-Pro-Glu, Ile-Pro-Gln) and phospholipids (phosphatidylinositol and phosphatidylserine). Meanwhile, the breast and leg muscles of 4 months chickens contained significantly higher amounts of aldehydes and ketones, contributing to enhanced umami and sweet taste profiles. In contrast, older chickens (8 months) exhibited significantly elevated levels of carnitine derivatives, which enhanced lipid oxidation and facilitated the generation of lipid-derived volatile organic compounds, resulting in a more pronounced and complex aromatic profile. Notably, metabolic differences between 6-month and 8-month chickens were minimal, suggesting that major biochemical shifts occur before 6 months of age. These findings provide valuable guidance for poultry producers in selecting optimal slaughter age based on desired meat attributes.

Keywords: Physicochemical features; Slaughter age; Slow growing chicken; Untargeted metabolomics.

Graphical abstract

Figure 1

Quality control analysis of breast and leg muscles samples from Lueyang black-bone chickens of different ages. (A, B) PCA score plots based on metabolites from negative and positive ion mix modes. (C, D) PLS-DA score plots based on metabolites from negative and positive ion mix modes. (E, F) Permutation tests were used to assess the accuracy of the PLS-DA models in negative and positive ion mix modes.CR4: 4-month-old chickens. CR6: 6-month-old chickens. CR8: 8-month-old chickens. BM: breast muscle. LM: leg muscle.

Figure 2

Screening and comparative analysis of differential metabolites. Upset diagrams were used in total differential metabolites in the BM (A) and LM (B), respectively. The variable importance in projection (VIP) analysis were used in the top 20 differentially metabolites (DMs) in the BM (C) and LM (D) from Lueyang black-bone chickens at different ages.

Figure 3

KEGG enrichment analysis of DMs in BM(A-C) and LM (D-F) from Lueyang black-bone chickens at different ages.

Figure 4

Temporal expression trend analysis of DMs in breast muscles (A and B) and leg muscles (C and D) of Lueyang black-bone chickens at different ages.

Figure 5

Analysis of volatile substances in the breast muscles (A) and leg muscles (B) of Lueyang black-bone chickens of different ages. The dots in the fingerprint represent volatile compounds. Black is the background, while low content is indicated by light blue, high content by yellow, and higher content by red.

Figure 6

Correlation analysis of differential metabolites with volatile substances in breast muscles (A) and leg muscles(B).