Supplementary L-arginine can enhance reproductive parameters and outcomes in large mammals

The amino acid L-arginine (Arg) is not only proteinogenic, but also a powerful regulator of cell physiology. Arg activates the mechanistic target of rapamycin directly, which regulates numerous kinase pathways. Arg also is metabolized to nitric oxide (a powerful cell signaling molecule) and polyamines, which stabilize proteins and DNA structurally. This Mini Review focusses on the effects of dietary Arg supplementation on reproductive parameters and outcomes in large mammalian species. Studies of Arg supplementation demonstrate consistent benefits to pregnancies in females and sperm quality in male livestock and men. We also present a summary of the numerous and rapid beneficial effects of <i>in vitro</i> Arg supplementation on sperm quality. Dietary and <i>in vitro</i> Arg also appear to reduce the damage to sperm caused by heat stress. However, there is an absence of Arg studies in stallions and dogs: two species that have substantial assisted reproductive technology done by veterinarians and others. Overall, Arg appears to be a safe, inexpensive, and natural supplement that is useful for improving reproductive outcomes in mammals.