Jugular arginine supplementation increases lactation performance and nitrogen utilization efficiency in lactating...

Area of Science:

• Animal Science
• Nutritional Biochemistry
• Dairy Cattle Physiology

Background:

• Arginine (Arg), a semi-essential amino acid (AA), positively influences milk production in lactating dairy cows when supplied post-ruminally.
• Understanding the impact of Arg on nitrogen (N) metabolism and milk synthesis is crucial for optimizing dairy cow nutrition.

Purpose of the Study:

• To investigate the effects of jugular infused L-arginine on milk production parameters in lactating dairy cows.
• To assess the impact of L-arginine on nitrogen absorption and utilization, including amino acid transporter gene expression and mammary uptake.

Main Methods:

• A replicated 3x3 Latin square design with six lactating Chinese Holstein cows was used.
• Treatments included Control (saline), L-arginine infusion, and an iso-nitrogenous L-alanine infusion.
• Measurements involved milk yield and composition, dry matter intake, N absorption, blood/milk urea N, and mammary AA transporter gene expression.

Main Results:

• L-arginine infusion increased milk yield, milk protein yield, and milk efficiency compared to controls.
• Arg supplementation upregulated amino acid transporter genes (SLC7A2, SLC7A8) and enhanced free AA uptake in the mammary gland.
• L-arginine reduced blood and milk urea nitrogen concentrations, indicating improved nitrogen utilization efficiency (NUE).

Conclusions:

• Enhancing post-ruminal arginine supply positively impacts milk protein synthesis in dairy cows.
• Increased mammary gland amino acid transporter expression and uptake are key mechanisms mediating Arg's benefits.
• Arginine supplementation improves nitrogen utilization efficiency and milk production performance.