Megan M. Ohrt
Nancy H. Ing*- Department of Animal Science, Texas A&M University, College Station, TX, United States
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 in vitro Arg supplementation on sperm quality. Dietary and in vitro 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.
1 Introduction
L-arginine (Arg) is a dietary amino acid that is, like others, incorporated into proteins. But perhaps more importantly, Arg has major roles in the regulation of metabolism. While Arg affects most physiological systems in mammals, its effects on reproduction are remarkable and have far-reaching consequences. Our objective is to review the multiple functions of Arg on physiology and the dietary supplementation studies that discovered beneficial effects on reproduction in livestock and human species. In addition, rapid effects on sperm in vitro are presented. Importantly, Arg supplementation in vivo and in vitro appears to protect sperm from damage induced by heat stress. Arg supplementation may provide one way that veterinary science professionals can use to enhance the reproductive efficiency of domestic animals around the world. For livestock species, this would make production more sustainable and ensure that high quality protein sources are available for our growing human population.
1.1 L-arginine (Arg) supplementation affects many physiological systems
Arg is one of the 20 amino acids that are the building blocks of animal proteins. In addition, Arg and its metabolites have several effects that regulate cell processes. For most mammals, Arg was traditionally classified as a nutritionally non-essential amino acid because the enterocytes of the intestine synthesize it. However, some species, including horses and cats do not synthesize Arg de novo (1, 2); thus, it is a nutritionally essential amino acid for them and is required in their diets. In addition to being proteinogenic, Arg is one of six “functional amino acids” that have major roles as regulators of key metabolic pathways (3). For example, Arg directly activates the mechanistic Target of Rapamycin (mTOR, a powerful protein kinase) pathway to increase protein synthesis. The Arg metabolites nitric oxide (NO) and polyamines are also very bioactive. Arg is metabolized by NO synthases to NO, which is a vasodilator, neurotransmitter, and signaling molecule involved in angiogenesis, regulation of cell metabolism, and apoptosis. Arg is also metabolized to polyamines: putrescine, spermine, and spermidine, which have central roles in gene expression, DNA and protein synthesis, and cell proliferation and differentiation (4, 5). Furthermore, dietary Arg supplementation improved cardiovascular and endothelial function in rats and humans (5). It also had positive effects on immune, muscle, brain function, metabolism, and tissue repair. In young men under stressful conditions, Arg supplementation enhanced neuroendocrine and cardiovascular health as well as mood (6). In neonatal pigs, Arg supplementation improved intestinal health and added lean muscle (7). In mice, Arg supplementation altered intestinal microbiota to increase beneficial bacteria (8). Together, these examples demonstrate that dietary Arg supplementation has remarkably positive effects on numerous physiological systems in mammals.
1.2 Dietary Arg supplementation is safe
Arg supplementation has been tested in numerous animal species and is generally safe with very few side effects (7). Arg is a component of normal diets, with humans eating up to 5 g daily (9). In humans, supplementation with very high doses of Arg [300 mg/kg body weight (BW)*day = 25 g per day for someone weighing 83 kg or 183 lbs.] is considered safe (10, 11). The effective doses in women and men are much lower, ranging from 3 to 14 g Arg per day for 1 to 4 weeks (Tables 1, 2). The only slightly deleterious effect of feeding Arg was found in mares fed 250 mg/kg BW (12). That Arg dosage interfered with the intestinal absorption of lysine and methionine, thereby decreasing serum concentrations of those two essential amino acids by 43 and 29%, respectively, at 2 h post-feeding. The lower dose of 125 mg Arg/kg BW in that study raised serum Arg concentrations by 240% without affecting serum lysine or methionine concentrations. Studies of pigs (13) and rats (14) indicate that long-term (90 days) dietary supplementation of <2% Arg in the diet did not result in any adverse effects.
Table 1. Arg supplementation in the diets of pregnant mammals improves reproductive outcomes.
Table 2. Arg supplementation in the diets of male mammals improves semen parameters.
1.3 Heat stress impairs semen quality and male fertility
Heat stress is occurring more frequently due to global warming, and it is affecting many temperate regions. The year 2024 was the warmest across the globe since record-keeping began in 1850 (15). Livestock producers worldwide are searching for strategies to mitigate heat stress (16, 17). The testis is the most heat-sensitive organ in mammals (18). In the scrotum, the testes reside at 33–35 °C. Heat stress in male livestock, including bulls, rams, and boars, has negative effects on sperm production, including decreased numbers, motility, and normal morphology as well as fertility (16, 18, 19). Even modest heat stress can have profound effects. For example, increasing the scrotal temperatures of rams by 1.2 °C for 12 h on four consecutive days resulted in severe decreases in sperm quality (20). 24 days later, sperm numbers were 30% lower, total motility was 0%, only 6% of sperm had normal morphology and 0% had fully intact DNA. Heat-stressed stallions suffer from subfertility, poor semen quality, and low serum testosterone (16, 21–24). Novel methods to reduce sperm damage from heat stress are needed.
2 Arg supplementation enhances reproductive parameters
2.1 Dietary Arg supplementation of pregnant females improves reproductive outcomes
Arg supplementation has many different positive effects on female reproduction (Table 1). Arg supplementation is used to treat serious hypertensive illnesses in pregnant women such as pre-eclampsia (5, 25). Female pigs and rats supplemented with Arg had more offspring and they had greater birthweights (26). Young female pigs supplemented between days 14 and 30 of the 112 day-long gestation period had increased embryonic survival, fetal weights, and placental vasculature and function (27). In pigs, Arg supplementation enhanced oocyte quality, embryo survival, fetal health, and placental function (5). Arg supplementation (100 mg Arg/kg BW*day) by intravenous injection increased serum prolactin and subsequent lactation in dairy cows (28). Given to pregnant mares, Arg doses ranging from 50 to 192 mg/kg BW*day increased embryo and fetal size, and blood flow in the uterine arteries, while it decreased insulin resistance (29–31, 61). Overall, Arg supplementation has tremendous potential to augment reproductive success in female mammals.
2.2 Dietary Arg supplementation improves reproductive parameters in males
In men, the effects of Arg supplementation on semen quality have been studied for eight decades and include increased sperm numbers, motility, and normal morphology (Table 2). Since 1944, dietary Arg has been known to be required for spermatogenesis in men and rats (4), and it is likely to be true for all mammals. In that study, three men were given a diet lacking Arg. Semen collected 9 days later showed 88% lower sperm counts and 95% lower motile sperm. The men were immediately placed on a normal diet and recovered to have normal semen parameters within 3 weeks. The Holt and Albanese study also reported that feeding male rats an Arg-deficient diet for 47 days destroyed the histoarchitecture of the seminiferous tubules, within which the male germ cells develop over 2 months. When Holt & Albanese (4) supplemented men with low sperm counts (oligospermia) with 122 mg Arg/kg BW*day, they detected increases in both sperm numbers (250%) and motility (100%) within 2 weeks. Tanimura (9) reported that supplementing men with 7 mg Arg/kg BW*day increased sperm counts by 60% within 2 weeks. Forty men with low percentages of motile sperm (asthenospermia) improved with 40 mg Arg/kg BW*day within 4 weeks (32). Both Arg metabolites NO and polyamines play important roles in spermatogenesis (33, 34). Arg supplementation of men also enhanced libido and is now used to treat erectile dysfunction: a daily supplement named Prelox® is marketed worldwide and contains 3 g Arg (35). These rapid and profound effects of Arg supplementation of men lead to studies in livestock.
Livestock studies with Arg supplementation identified the effects on semen that were seen in men (Table 2), as well as increased chromatin condensation in sperm heads and serum testosterone. Arg supplementation of boars (100 mg/kg BW*day) enhanced semen quality, including increased sperm counts (3). Testosterone is involved in many aspects of spermatogenesis (36). Testosterone drives chromatin condensation in late spermatogenesis when protamine proteins (made up of 50% Arg) replace 85% of histone in chromatin. Arg supplementation increased chromatin condensation in sperm of boars (19%; (37)) and rams (23%; (38)). Note that ruminants can be injected intravenously or intraperitoneally with Arg or fed a coated “rumen-protected” Arg supplement to bypass metabolism by the rumen. In Ozer Kaya et al. (39), rams injected once with 5 mg Arg/kg BW showed increased in sperm numbers (144%) and motility (47%), respectively, within 5 days. Supplementation of rams with rumen-protected Arg for 4 weeks enhanced sperm numbers (166%), motility (11%), sperm with normal morphology (17%), and serum testosterone concentrations (19%), as well as libido (37). These data demonstrate significant semen improvements in short time frames and provide compelling reasons to use Arg supplementation to optimize male reproduction. Notably, although stallions frequently have periods of subfertility (40), Arg supplementation has not yet been tested in them.
2.3 In vitro Arg supplementation improves sperm quality parameters
In vitro studies of sperm from major livestock species have demonstrated that Arg improves specific sperm quality parameters. In a study using goat sperm isolated from the caudal epididymis, 5 mM Arg added to sperm in Sp-TALP medium at 37 °C increased the percentage of total sperm motility by 16%, capacitated sperm by 38% after 4 h of incubation (41). They discovered that the in vitro Arg supplementation up-regulated the levels of four mRNAs in sperm that are involved in motility: phosphoglycerate kinase 2 (PGK2), ribonuclease 10 (RNASE10), outer dense fiber of sperm tails 1 (ODF1), and rhophilin associated tail protein 1 like (ROPN1L). Changes in mRNA levels in sperm are likely caused by altered stabilities. The mRNAs in sperm are fragmented to an average length of 250 nucleotides and are unlikely to be translated (42). However, the RNAs that sperm deliver to oocytes at fertilization are critical for embryo development (43). In a study of ejaculated boar sperm, the addition of 1 mM Arg to Ham’s F10 medium before a 1 h of incubation at 39 °C increased the percentage of total sperm motility by 14% and progressively motile sperm by 18% and the 1 mM dose of Arg was more effective than 2 mM (44). It is noteworthy that the percentage of motile sperm in all of these in vitro systems decreases over time. While the effects of Arg supplementation are reported as increases in motility at a time point, they may be more correctly stated as preservation of motility or prevention of its loss. Supplementation of boar sperm with 1 mM Arg also decreased levels of cytochrome c oxidase subunit 5B (COX5B) mRNA by 79% and reactive oxygen species (ROS) by 52% while it increased the percentage of sperm with high mitochondrial membrane potential (ΔΨm) by 18% and the activity of mitochondrial respiratory chain complex V (MRCCV) by 33% (44). This implicates Arg in the regulation of mitochondrial oxidative phosphorylation (OXPHOS) on sperm. Ejaculated, frozen and thawed bull sperm were incubated in Sp-TALP lacking or containing 1 mM Arg for 3 h at 38.5° (45). Arg supplementation increased motile sperm by 12%, capacitated sperm by 12%, and sperm with high mitochondrial membrane potential by 20%. Concurrently, proteomic analyses identified 367 proteins, with 11 up-regulated and 29 down-regulated by Arg supplementation. Intriguingly, the A-kinase anchoring protein 3 (AKAP3) was uniquely expressed highly in sperm with Arg supplementation. The ROPN1L mRNA up-regulated by Arg in goat sperm (41) encodes a protein that interacts with AKAP3 protein. In a study performed with ejaculated ram sperm supplementation with 10 mM Arg in complete TALP medium for 3 h at 39 °C, the Arg elevated the percentage of capacitated sperm by 11% and the percentage of acrosome-reacted sperm by 15% compared to controls (46). Coordinately, the percentage of live sperm with high nitric oxide (NO) levels increased by 7%. Based on these studies of goat, boar, bull, and ram sperm, it is apparent that Arg supplementation in vitro had positive impacts on several sperm quality parameters including increased motility, NO levels, and ΔΨm, along with decreased ROS, and altered expression of genes involved in motility.
2.4 Proteomic studies highlight the importance of Arg and its metabolism in male reproduction
With managers commonly using assisted reproductive technologies with stallions, proteomic studies help lead that methodology (47). A recent publication identified 140 differentially expressed proteins in sperm from fertile versus subfertile stallions that carry a susceptibility genotype (FKBP6 mutation) for impaired acrosome function (48). Stallion sperm parameters, including sperm motility, have related to fertility and differential abundance of specific proteins (49). A study of stallion semen collected during periods of higher and lower fertility identified 38 differentially expressed proteins (40). Proteomic comparisons of bovine caudal epididymal fluid and seminal plasma identified differential expression of proteins within 28 KEGG pathways, including “Arginine and proline metabolism” (50). In vitro supplementation of bull sperm with 1 mM Arg for 3 h up-regulated 11 and down-regulated 27 sperm proteins (45). One of the down-regulated proteins was ornithine decarboxylase antizyme 3 (OAZ3), which is prominent within the Arg metabolic pathway. This is consistent with our identification of lower OAZ3 mRNA levels in more dense (more functional) stallion sperm compared to less dense sperm (51).
Studies of sperm proteins that are related to functional characteristics enhance our understanding of gamete physiology. Although sperm do not synthesize proteins, their membranes actively exchange proteins within the epididymis (52). In stallions, sperm spend the last 9 days of the spermatogenic cycle in the epididymis (53). Dietary Arg supplementation increases sperm numbers maximally within days to weeks (4, 39), so it would be plausible their action on sperm in the epididymis to enhance survival and development (54).
2.5 Arg supplementation can mitigate the effects of heat stress on male reproduction
There is one study of dietary Arg supplementation of boars before and during summer, improving sperm numbers, motility, and morphology as well as increasing serum testosterone and libido (38). Interestingly, even a single intramuscular injection of 5 mg Arg/kg BW given to rams in severe environmental heat stress increased serum testosterone and NO concentrations and testicular artery blood flow (55). Remarkably, rams that underwent scrotal insulation weeks before semen collection had increased sperm motility, sperm with normal morphology, and intact DNA after freeze-thawing when the extender contained 1 mM Arg (56). The benefits of Arg supplementation of male mice subjected to heat stress include 39% greater progressive motility of sperm and 40% higher serum testosterone (8). Remarkably, transplantation of fecal microbiota from Arg-treated mice enhanced the progressive motility of sperm by 109% and serum testosterone by 24% after heat stress compared to male mice receiving fecal microbiota from mice lacking Arg supplementation. Together, these data reflect on the broad effects of dietary Arg supplementation to promote the health of male reproduction, even in conditions of heat stress.
3 Discussion
Arg is a remarkable amino acid for its many functions. Not only is it a building block of proteins, but also it directly activates mTOR and associated kinase pathways. Arg indirectly is involved in cell signaling by being metabolized to NO, which has numerous tissue effects including vasodilation. Arg is also metabolized to polyamines, which play critical roles in stabilizing DNA and protein structures. These mechanisms are involved with the results seen from Arg supplementation in livestock and humans. Dietary supplementation with Arg is safe, economical, easy (usually top-dressing grain), and it is beneficial to reproductive outcomes. Many effects of Arg are rapid, occurring within hours to days. This implicates the cell signaling effects of Arg, among others. In pregnant females, it increased fetal size and birthweights. In males, dietary supplementation of Arg enhanced factors ranging from libido to sperm motility. It is exciting that even addition of Arg to semen extender before freezing increases sperm motility and decreases DNA fragmentation at thawing. The studies that demonstrate the Arg supplementation protects sperm from damage by heat in vivo and in vitro are additional incentives to use it in promoting reproduction during environmental stressors. Future studies could address the effects of dietary Arg on female breeding success and in vitro Arg effects on ova. In addition, the combined effects of dietary and in vitro Arg supplementation remain to be investigated in males and females. The future appears bright for using Arg supplementation for enhancing reproductive outcomes in mammals.
4 Conclusion
Arg supplementation, dietary and in vitro, are examples of how veterinary science can assist livestock producers in improving reproductive efficiency. It joins other approaches by scientists and producers to optimize livestock production. This will make livestock production more sustainable and beneficial for the health of animals, people, and the environment.
Author contributions
MO: Investigation, Writing – original draft, Writing – review & editing. NI: Conceptualization, Supervision, Writing – original draft, Writing – review & editing.
Funding
The author(s) declared that financial support was received for this work and/or its publication. The authors thank the Department of Animal Science for providing funds for the publication of this article.
Conflict of interest
The author(s) declared that this work was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Generative AI statement
The author(s) declared that Generative AI was not used in the creation of this manuscript.
Any alternative text (alt text) provided alongside figures in this article has been generated by Frontiers with the support of artificial intelligence and reasonable efforts have been made to ensure accuracy, including review by the authors wherever possible. If you identify any issues, please contact us.
Publisher’s note
All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.
References
1. Li, P, and Wu, G. Amino acid nutrition and metabolism in domestic cats and dogs. J Anim Sci Biotechnol. (2023) 14:19. doi: 10.1186/s40104-022-00827-8,
2. Martinez, RE, Leatherwood, JL, Bradberry, AN, Silvers, BL, Fridley, J, Arnold, CE, et al. Equine enterocytes actively oxidize L-glutamine but do not synthesize L-citrulline or L-arginine from L-glutamine or L-proline in vitro. J Anim Sci. (2022) 100:1–7. doi: 10.1093/jas/skac077,
3. Wu, G, Bazer, FW, Spencer, TE, Yin, Y-L, and Kim, SW. New developments in amino acid research In: A Rosati, A Tewolde, and C Mosconi editors. WAAP book of the year 2006. (Gelderland, Netherlands: Wageningen Academic Publisher) (2007) 299–315.
4. Holt, LE, and Albanese, AA. Observations on amino acid deficiencies in man. Trans Assoc Am Phys. (1944) 58:143–56.
5. Wu, G, Bazer, FW, Davis, TA, Kim, SW, Li, P, Rhoads, JM, et al. Arginine metabolism and nutrition in growth, health and disease. Amino Acids. (2009) 37:153–68. doi: 10.1007/s00726-008-0210-y,
6. Apolzan, JW, Stein, JA, Rood, JC, Beyl, RA, Yang, S, Greenway, FL, et al. Effects of acute arginine supplementation on neuroendocrine, cardiovascular and mood outcomes in younger men: a double-blind, placebo-controlled trial. Nutrition. (2022) 101:111658. doi: 10.1016/j.nut.2022.111658,
7. Wu, G, Bazer, FW, Cudd, TA, Jobgen, WS, Kim, SW, Lassala, A, et al. Pharmacokinetics and safety of arginine supplementation in animals. J Nutr. (2007) 137:1673S–80S. doi: 10.1093/jn/137.6.1673s,
8. Wang, K, Suo, Y, Shen, D, Shi, Y, Jin, X, Li, Y, et al. Improvement in heat stress-induced damage to sperm quality following fecal microbiota transplantation from L-arginine-treated mice. Animals. (2025) 15:796. doi: 10.3390/ani15060796
9. Tanimura, J. 1967 Studies on arginine in human semen: part II. The effects of medication with L-arginine HCl on male infertility Bull Osaka Med Sch 13 84–89. Available online at: https://pubmed.ncbi.nlm.nih.gov/6080242/
10. Cynober, L, Bier, DM, Kadowski, M, Morris, SM, Elango, R, and Smriga, M. Proposals for upper limits of safe intake for arginine and tryptophan in young adults and an upper limit of safe intake for leucine in the elderly. J Nutr. (2016) 146:2652S–4S. doi: 10.3945/jn.115.228478,
11. McNeal, CJ, Meninger, CJ, Reddy, D, Wilborn, CD, and Wu, G. Safety and effectiveness of arginine in adults. J Nutr. (2016) 146:2587S–93S. doi: 10.3945/jn.116.234740
12. Kelley, DE, Warren, LK, and Mortensen, CJ. Orally supplemented L-arginine impairs amino acid absorption depending on dose in horses. J Anim Sci. (2014) 92:5560–6. doi: 10.2527/jas.2014-7690,
13. Hu, SD, Li, XL, Rezaei, R, Meninger, CJ, McNeal, CJ, and Wu, G. Safety of long-term dietary supplementation with L-arginine in pigs. Amino Acids. (2015) 47:925–36. doi: 10.1007/s00726-015-1921-5,
14. Yang, Y, Wu, Z, Jia, S, Dahanayaka, S, Feng, S, Meninger, CJ, et al. Safety of long-term dietary supplementation with L-arginine in rats. Amino Acids. (2015) 47:1909–20. doi: 10.1007/s00726-015-1992-3,
15. NOAA National Centers for Environmental Information (2025). Available online at: https://www.ncei.noaa.gov/access/metadata/landing-page/bin/iso?id=gov.noaa.ncdc:C00672 (Accessed April 18, 2025).
16. Moula, AB, Moussafir, Z, Hamidallah, N, and Amiri, BE. Heat stress and ram semen production and preservation: exploring impacts and effective strategies. J Therm Biol. (2024) 119:103794. doi: 10.1016/j.jtherbio.2024.103794,
17. Renaudeau, D, and Dourmad, JY. Review: future consequences of climate change for European Union pig production. Animal. (2022) 16:100372. doi: 10.1016/j.animal.2021.100372,
18. Setchell, BP. The Parkes lecture: heat and the testis. J Reprod Fertil. (1998) 114:179–94. doi: 10.1530/jrf.0.1140179,
19. Wettere, WHEJ, Kind, KL, Gatford, KL, Swinbourne, AM, Leu, ST, Hayman, PT, et al. Review of the impact of heat stress on reproductive performance of sheep. J Anim Sci Biotechnol. (2021) 12:26. doi: 10.1186/s40104-020-00537-z,
20. Viana Neto, AM, Guerreirro, DD, Martins, JAM, Vasconcelos, FR, Melo, RBF, Velho, ALMCS, et al. Sperm traits and seminal plasma proteome of locally adapted hairy rams subjected to intermittent scrotal insulation. Anim Reprod Sci. (2024) 263:107439. doi: 10.1016/j.anireprosci.2024.107439,
21. Blanchard, T., Varner, D., Johnson, L., Roser, J., Hill, J., and Miller, C. 2000 Testicular and hormonal changes in stallions with thermally induced testicular degeneration J Reprod Fertil Suppl 56 51–59. Available online at: https://pubmed.ncbi.nlm.nih.gov/20681115/
22. Freidman, R., Scott, M., Heath, S.E., Hughes, J.P., Daels, P.F., and Tran, T.Q. 1991 The effects of increase testicular temperature on spermatogenesis in the stallion J Reprod Fertil Suppl 44 127–134. Available online at: https://pubmed.ncbi.nlm.nih.gov/1795255/
23. Love, CC, and Kenney, RM. Scrotal heat stress induces altered sperm chromatin structure associated with a decrease in protamine disulfide bonding in the stallion. Biol Reprod. (1999) 60:615–20. doi: 10.1095/biolreprod60.3.615,
24. Shakeel, M, and Yoon, M. Heat stress and stallion fertility. J Anim Sci Technol. (2023) 65:683–97. doi: 10.5187/jast.2023.e29,
25. Menichini, D, Feliciello, L, Neri, I, and Facchinetti, F. L-arginine supplementation in pregnancy: a systematic review of maternal and fetal outcomes. J Matern Fetal Neonatal Med. (2023) 36:2217465. doi: 10.1080/14767058.2023.2217465,
26. Mateo, RD, Wu, G, Bazer, FW, Park, JC, Shinzato, I, and Kim, SW. Dietary L-arginine supplementation enhances the reproductive performance of gilts. J Nutr. (2007) 137:652–6. doi: 10.1093/jn/137.3.652,
27. Herring, CM, Bazer, FW, Johnson, GA, Seo, H, Hu, SD, Elmetwally, M, et al. Dietary supplementation with 0.4% L-arginine between days 14 and 30 of gestation enhances NO and polyamine syntheses and water transport in porcine placentae. J Anim Sci Biotechnol. (2022) 13:134–13. doi: 10.1186/s40104-022-00794-0,
28. Chew, BP, Eisenman, JR, and Tanaka, TS. Arginine infusion stimulate prolactin, growth hormone, insulin, and subsequent lactation in pregnant dairy cows. J Dairy Sci. (1983) 67:2507–18. doi: 10.3168/jds.s0022-0302(84)81607-0,
29. Aurich, J, Köhne, M, Wulf, M, Nagel, C, Beythien, E, Gautier, C, et al. Effects of dietary L-arginine supplementation to early pregnant mares on conceptus diameter—preliminary findings. Reprod Domest Anim. (2019) 54:772–8. doi: 10.1111/rda.13422,
30. Martinez, RE, Leatherwood, JL, Bradberry, AN, Paris, BL, Hammer, CJ, Kelley, D, et al. Evaluation of dietary arginine supplementation to increase nutrient transporters in aged mares. Transl Anim Sci. (2023) 7:txad058. doi: 10.1093/tas/txad058,
31. Robles, M, Coutureier-Tarrade, A, Derisoud, E, Geeverding, A, Dubois, C, Dahirel, M, et al. Effects of dietary arginine supplementation in pregnant mares on maternal metabolism, placental structure and function and foal growth. Sci Rep. (2019) 9:6461. doi: 10.1038/s41598-019-42941-0,
32. Scibona, M, Meschini, P, Capparelli, S, Pecori, C, Rossi, P, and Menchini Fabris, GF. L-arginine and male infertility. Minerva Urol Nefrol. (1994) 46:251–3.
33. Lefèvre, PL, Palin, M-F, and Murphy, BD. Polyamines on the reproductive landscape. Endocr Rev. (2011) 32:694–712. doi: 10.1210/er.2011-0012,
34. Srivastava, S, Desai, P, Coutinho, E, and Govil, G. Mechanism of action of L-arginine on the vitality of spermatozoa is primarily through increased biosynthesis of nitric oxide. Biol Reprod. (2006) 74:954–8. doi: 10.1095/biolreprod.105.046896,
35. Stanislavov, R, Nikolova, V, and Rohdewald, P. Improvement of seminal parameters with Prelox: a randomized, double-blind, placebo-controlled, cross-over trial. Phytother Res. (2009) 23:297–302. doi: 10.1002/ptr.2592,
36. Gill-Sharma, MK. Prolactin and male fertility: the long and short feedback regulation. Int J Endocrinol. (2009) 2009:687259. doi: 10.1155/2009/687259,
37. Hussein, HA, Hassaneen, ASA, Ali, ME, Sindi, RA, Ashour, AM, Fahmy, SM, et al. The impact of rumen-protected L-arginine oral supplementation on libido, semen quality, reproductive organ biometry, and serum biochemical parameters of rams. Front Vet Sci. (2022) 9:899434. doi: 10.3389/fvets.2022.899434,
38. Chen, JQ, Li, YS, Li, ZJ, Lu, HX, Zhu, PQ, and Li, CM. Dietary L-arginine supplementation of boars under high ambient temperature. Animal. (2018) 12:1611–20. doi: 10.1017/s1751731117003147
39. Ozer Kaya, SO, Kandemir, FM, Gur, S, Erisir, M, Benzer, F, Ozer Kaya, E, et al. Evaluation of the role of L-arginine on spermatological parameters, seminal plasma nitric oxide levels and arginase enzyme activities in rams. Andrologia. (2019) 52:e13439. doi: 10.1111/and.13439
40. Griffin, RA, Swegen, A, Baker, MA, Ogle, RA, Smith, N, Aitken, RJ, et al. Proteomic analysis of spermatozoa reveals caseins play a pivotal role in preventing short-term periods of subfertility in stallions. Biol Reprod. (2022) 106:741–55. doi: 10.1093/biolre/ioab225,
41. Sahoo, B, and Gupta, MK. Effect of arginine-induced motility and capacitation on RNA population in goat spermatozoa. Vet Res Commun. (2023) 47:1427–44. doi: 10.1007/s11259-023-10092-3,
42. Ing, NH, Konganti, K, Ghaffari, N, Johnson, CD, Forrest, DW, Love, CC, et al. Identification and quantification of coding and long non-coding RNAs in stallion spermatozoa separated by density. Andrology. (2020) 8:1409–18. doi: 10.1111/andr.12791,
43. Ing, NH, Konganti, K, Ghaffari, N, Johnson, CD, Forrest, DW, Love, CC, et al. Specific microRNAs in stallion spermatozoa are potential biomarkers of high functionality. Reprod Domest Anim. (2024) 59:e14674. doi: 10.1111/rda.14674
44. Li, Y, Chen, J, Li, Z, and Li, C. Mitochondrial OXPHOS is involved in the protective effects of L-arginine against heat-induced low sperm motility. J Therm Biol. (2019) 84:236–44. doi: 10.1016/j.jtherbio.2019.07.008,
45. Maciel, VL Jr, Caldas-Bussiere, MC, Silveira, V, Reis, RS, Rios, AFL, and Paes de Carvalho, CS. L-arginine alters the proteome of frozen-thawed bovine sperm during in vitro capacitation. Theriogenology. (2018) 119:1–9. doi: 10.1016/j.theriogenology.2018.06.018,
46. Miguel-Jiménez, S, Carvajal-Serna, M, Calvo, S, Casao, A, Cebrián-Pérez, JÁ, Muiño-Blanco, T, et al. Does melatonin exert its effect on ram sperm capacitation through nitric oxide synthase regulation? Int J Mol Sci. (2020) 21:2093. doi: 10.3390/ijms21062093,
47. Peña, FJ, Martin-Cano, FE, Becerro-Rey, L, Ortega-Ferrusola, C, Gaitskell-Phillips, G, Silva-Alvarez, E, et al. Proteomics is advancing the understanding of stallion sperm biology. Proteomics. (2024) 24:e2300522. doi: 10.1002/pmic.202300522
48. Hernández-Avilés, C, Ramirez-Agamez, L, Weintraub, ST, Scoggin, CF, Davis, BW, Raudsepp, T, et al. Proteomic analysis of sperm from fertile stallions and subfertile stallions due to impaired acrosomal exocytosis. Sci Rep. (2024) 14:12446. doi: 10.1038/s41598-024-63410-3,
49. Gaitskell-Phillips, G, Martin-Cano, FE, Ortiz-Rodriguez, JM, Silva-Rodriguez, A, Silva-Alvarez, W, Rojo-Dominguez, P, et al. Proteins involved in mitochondrial metabolic functions and fertilization predominate in stallions with better motility. J Proteome. (2021) 247:104335. doi: 10.1016/j.jprot.2021.104335,
50. Zoca, SM, Northrup-Albrecht, EJ, Walker, JA, Cushman, RA, and Perry, GA. Proteomic analyses identify differences between bovine epididymal and ejaculated spermatozoa that contribute to longevity. Theriogenology. (2022) 184:51–60. doi: 10.1016/j.theriogenology.2022.02.021,
51. Ing, NH, Forrest, DW, Love, CC, and Varner, DD. Dense spermatozoa in stallion ejaculates contain lower concentrations of mRNAs encoding the sperm specific calcium channel 1, ornithine decarboxylase antizyme 3, aromatase, and estrogen receptor alpha than less dense spermatozoa. Theriogenology. (2014) 82:347–53. doi: 10.1016/j.theriogenology.2014.04.016,
52. Girouard, J, Frenette, G, and Sullivan, R. Comparative proteome and lipid profiles of bovine epididymosomes collected in the intraluminal compartment of the caput and cauda epididymis. Int J Androl. (2011) 34:e475–86. doi: 10.1111/j.1365-2605.2011.01203.x,
53. Johnson, L, Blanchard, TL, Varner, DD, and Scrutchfield, WL. Factors affecting spermatogenesis in the stallion. Theriogenology. (1997) 48:1199–216. doi: 10.1016/s0093-691x(97)00353-1,
54. Jones, R. Sperm survival versus degradation in the mammalian epididymis: a hypothesis. Biol Reprod. (2004) 71:1405–11. doi: 10.1095/biolreprod.104.031252,
55. El-Shalofy, AS, Samir, H, and El-Sherbiny, HR. Intramuscular administration of L-arginine boosts testicular hemodynamics, plasma concentrations of testosterone and nitric oxide in heat-stressed rams. Theriogenology. (2023) 197:127–32. doi: 10.1016/j.theriogenology.2022.11.030,
56. Shahat, AM, Thundathil, JC, and Kastelic, JP. Melatonin or L-arginine in semen extender mitigate reductions in quality of frozen-thawed sperm from heat-stressed rams. Anim Reprod Sci. (2022) 238:106934. doi: 10.1016/j.anireprosci.2022.106934,
57. Rytlewski, K, Olszanecki, R, Lauterbach, R, Grzyb, A, and Basta, A. Effects of oral L-arginine on the foetal condition and neonatal outcome in preeclampsia: a preliminary report. Basic Clin Pharmacol Toxicol. (2006) 99:146–52. doi: 10.1111/j.1742-7843.2006.pto_468.x,
58. Hladunewich, MA, Derby, GC, Lafayette, RA, Blouch, KL, Druzin, ML, and Myers, BD. Effect of L-arginine therapy on the glomerular injury of preeclampsia. Obstet Gynecol. (2006) 107:886–95. doi: 10.1097/01.aog.0000207637.01824.fe,
59. Valdivia-Silva, J.E., Lopez-Molina, K., and Macedo, R. 2009 Efecto de la terapia temprana con L-arginina en el crecimiento intrauterine restringido en la preclampsia Prog Obstet Ginecol 52 89–98. Available online at: https://www.elsevier.es/es-revista-progresos-obstetricia-ginecologia-151-articulo-efecto-terapia-temprana-con-l-arginina-S0304501309703425
60. Vadillo-Ortega, F, Perichart-Perera, O, Espino, S, Avila-Vergara, MA, Ibarra, I, Ahued, R, et al. Effect of supplementation during pregnancy with l-arginine in medical food on pre-eclampsia in high risk population. BMJ. (2011) 342:d2901. doi: 10.1136/bmj.d2901
Keywords: dietary supplement, fertility, heat stress, pregnancy, semen quality, spermatozoa
Citation: Ohrt MM and Ing NH (2026) Supplementary L-arginine can enhance reproductive parameters and outcomes in large mammals. Front. Vet. Sci. 12:1740399. doi: 10.3389/fvets.2025.1740399
Edited by:
Regiane R. Santos, Schothorst Feed Research, NetherlandsReviewed by:
Patrick Martin, UniLaSalle, FranceCopyright © 2026 Ohrt and Ing. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Nancy H. Ing, TmFuY3kuSW5nQGFnLnRhbXUuZWR1