L-Arginine Nutrition and Metabolism in Ruminants.

Area of Science:

• Nutritional biochemistry and animal science.
• Ruminant metabolism and physiology.

Background:

• L-arginine (Arg) is crucial for nitrogen metabolism, blood flow, and nutrient utilization in ruminants.
• Ruminants synthesize Arg from L-glutamine, L-glutamate, and L-proline via L-citrulline (Cit) in enterocytes.
• Endogenous Arg synthesis meets most requirements, leading to Arg not being traditionally considered a limiting nutrient.

Purpose of the Study:

• To investigate the role of L-arginine (Arg) and L-citrulline (Cit) in ruminant nutrition.
• To evaluate the impact of dietary supplementation with rumen-protected Arg or unencapsulated Cit on ruminant production and health.
• To address suboptimal efficiencies in milk production, reproduction, and growth attributed to a lack of understanding of Arg metabolism.

Main Methods:

• Review of existing evidence on L-arginine (Arg) and L-citrulline (Cit) metabolism in ruminants.
• Analysis of the effects of dietary supplementation with rumen-protected Arg on production indices.
• Assessment of the efficacy of unencapsulated Cit as a dietary source for Arg synthesis in ruminants.

Main Results:

• Dietary supplementation with rumen-protected Arg (0.25-0.5% of dietary dry matter) improves milk production, reproductive performance, and growth.
• Supplementation with Arg or Cit does not adversely affect ruminant metabolism or health.
• Unencapsulated L-citrulline (Cit) serves as an effective dietary source for L-arginine (Arg) synthesis in ruminants due to its resistance to ruminal degradation.

Conclusions:

• Dietary L-arginine (Arg) or L-citrulline (Cit) supplementation is necessary to support maximum survival, growth, lactation, and reproductive performance in ruminants.
• Adequate supplementation enhances feed efficiency, health, and well-being in dairy and beef cattle, sheep, and goats.
• Rumen-protected Arg or unencapsulated Cit are essential for optimizing ruminant production and health.