Arginine is an amino acid that intervenes in the synthesis of protein for muscle growth. It also plays other multiple metabolic functions: it is the substrate for the biosynthesis of different molecules of metabolic importance such as nitric oxide, GAA, glutamate, ornithine and proline (Figure 1).
Nitric oxide is an important mediator in vasodilatation, contributing to an increase in blood flow to the organs. This nitric oxide, in turn, reduces the fat synthesis and promotes fat oxidation. Arginine also improves the performance of the carcass, especially the muscles of the breast in broilers via synthesis of glutamate and proline. Glutamate, proline and hydroxyproline are, in turn, important in connective tissue synthesis. Similarly, other molecules synthesized from L-Arginine, such as ornithine and polyamines, contribute to the synthesis of DNA and RNA in normal cell growth. On the other hand, GAA is a normal metabolite of arginine that participates in the energy buffer system at the muscular level.
In short, L-Arginine improves the efficiency and quality of meat by increasing the amount of protein and reducing fat.
Figure 1. Functions of L-Arginine in different metabolic pathways (adapted from Fouad et al., 2012)
Chickens cannot synthesize L-Arginine due to the unavailability of two separate enzymes in the urea cycle in the kidney and the absence of almost all enzymes in the urea cycle in the liver. That makes L-Arginine an essential amino acid for chickens to be added to the diet.
Until now there was no L-Arginine on the market registered as a feed additive, which is why Guanadinoacetic Acid (GAA) was used. This GAA is the precursor to creatine and is synthesized from arginine. Initially, GAA has been used to save the naturally occurring L-Arginine in some foods so that the animal can use it for other metabolic functions. However, there are studies that demonstrate the advantages of directly supplementing L-Arginine versus GAA.
Fortunately, this is already possible because in Quimidroga we have L-Arginine as a registered additive for animal feed and that allows adding this amino acid directly in diets.