Rumen-Plasma-Milk Metabolomics Profiling Revealed Metabolic Alterations Associated with Milk Fat Synthesis in Chinese...

Area of Science:

• Animal Science
• Metabolomics
• Nutritional Biochemistry

Background:

• Milk fat synthesis is a complex process influenced by ruminal fermentation, systemic metabolism, and mammary gland activity.
• Understanding the metabolic interplay across these systems is crucial for optimizing dairy cow production.

Purpose of the Study:

• To investigate the metabolic differences in rumen fluid, plasma, and milk between Chinese Holstein cows with high and low milk fat content.
• To evaluate the role of malic acid (MA) in regulating lipid metabolism within bovine mammary epithelial cells (BMECs).

Main Methods:

• A multi-tissue metabolomics approach using ultra-high-performance liquid chromatography-mass spectrometry (UHPLC-MS) on rumen fluid, plasma, and milk samples.
• In vitro culture of BMECs to assess the impact of MA on lipid metabolism and gene/protein expression.

Main Results:

• Distinct metabolic profiles were identified across the three tissues between high (H-MF) and low (L-MF) milk fat groups.
• H-MF cows showed metabolites linked to fatty acid biosynthesis and lipogenesis, while L-MF cows exhibited markers of amino acid metabolism and liver stress.
• Malic acid (MA) was elevated in L-MF milk and, in vitro, inhibited triglyceride accumulation and lipogenic gene expression in BMECs.

Conclusions:

• Rumen, plasma, and milk metabolites collectively influence milk fat synthesis in dairy cows.
• Malic acid (MA) plays a significant role as a regulator of lipid metabolism in mammary epithelial cells, potentially impacting milk fat content.