Effects Of Dietary Arginine Supplementation Research Articles

Effects of dietary arginine supplementation on growth performance, antioxidant capacity, intestinal digestive enzyme activity, muscle transcriptome, and gut health of Siniperca chuatsi

Our study investigated the effects of dietary arginine supplementation on the growth performance, antioxidant capacity, intestinal digestive enzyme activity, muscle transcriptome, and gut health of Chinese perch (Siniperca chuatsi). Four isonitrogenous and isolipidic diets (50% crude protein, 11% crude lipid) with graded levels (2.61%, 2.99%, 3.37%, and 3.82%) of arginine were formulated and processed. A total of 360 Chinese perch (approximately 45–46 g) were randomly divided into four groups with triplicates of 30 fish per cage in each group. Our results revealed that although there was no significant improvement in the growth performance of Chinese perch, their antioxidant capacity and nutritional metabolism were significantly improved. Compared to the control group (without arginine supplementation, 2.61% group), feeding graded arginine levels could significantly (P < 0.05) decrease serum glucose and malondialdehyde (MDA) contents, as well as increase total superoxide dismutase (TSOD) activity. Fish fed a 3.37% arginine diet had the highest TSOD activity in the serum and liver. The intestinal morphological structure was clearer and more uniform in the 2.99% and 3.37% arginine groups. Fish fed with 3.82% arginine had significantly decreased (P < 0.05) muscle valine, glutamate, tyrosine, and total non-essential amino acid contents, with decreased (P < 0.05) intestinal amylase activity. Transcriptome analysis showed that graded arginine levels significantly (P < 0.05) influenced muscle gene expression involved in the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways of energy metabolism (amino acid, glucose, fatty acid), signaling pathways (mTOR, PI3K-Akt, MAPK, foxO, and insulin pathway), etc. The microbial community structure did not change significantly. Mycoplasma showed the highest abundance in the control group, and Cetobacterium had the highest abundance in the dietary arginine supplementation groups. Network analysis showed that the network complexity of the control group was higher than those of arginine groups. Our finding would help advance the field of arginine nutrition and guide the development of future fish feeds. Based on antioxidant and intestinal health indicators, the optimal dietary arginine requirement for Chinese perch was 2.99%–3.37% of the dry diet (6.08%–6.79% of dietary protein).

Effect of dietary arginine supplementation on protein synthesis, meat quality and flavor in growing lambs

This study aimed to assess the effect of dietary arginine supplementation on protein synthesis, meat quality and flavor in lambs. Eighteen Dorper (♂) × Small Tailed Han sheep (♀) crossed ewe lambs of similar weight (27.29 ± 2.02 kg; aged 3 months) were assigned to two groups, the control group was fed the basal diet (Con group), and the arginine group (Arg group) was supplemented with 1% l-arginine based on the Con group for 90 d. The results suggested that dietary arginine significantly increased final body weight, loin eye muscle area, muscle fiber diameter, cross-sectional area (P < 0.050), and decreased shear force value and cooking loss (P < 0.050), as well as altered the composition and contents of volatile flavor compounds in lambs. Importantly, the total protein (TP) content, alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (AKP) activities in serum, branched-chain aminotransferase (BCAT), AST, ALT activities and neuronal nitric oxide synthase (nNOS) gene expression and content were elevated (P < 0.050), while content of urea nitrogen (BUN) in serum and 3-methylhistidine (3-MH) were decreased in arginine fed lambs (P < 0.050). In addition, arginine triggered muscle protein synthesis through protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signaling pathway, while minimized protein degradation by regulating gene expression of myogenin (MyoG), myostatin (MSTN), muscle atrophy F-box (MAFbx) and forkhead box O3 family (FoxO3) (P < 0.050). Taken together, this study suggested that arginine can be used to improve protein deposition and meat quality in lamb production.

Effects of dietary arginine supplementation on production performance, serum biochemicals, antioxidant capacity, and immunity of laying Wulong geese

This study investigated the effects of dietary arginine supplementation on the production performance, serum biochemicals, antioxidant capacity, and immunity of laying Wulong geese. A total of 150 Wulong geese (34-wk old) with similar body weights were randomly divided into 6 groups with 5 replicates and 5 geese each (1 male and 4 female). The geese in the control group were fed a corn-rapeseed meal basal diet, and the geese in the treatment groups were fed the basal diet supplemented with 0.1, 0.2, 0.3, 0.4, and 0.5% arginine. The experiment lasted for 17 wk. Our results showed that dietary arginine increased the egg production rate (LR) and average egg weight (AEW) of geese in a quadratic manner (P < 0.05). Dietary arginine had a quadratic effect on the contents of total protein (TP) and triglyceride (TG) (P < 0.05) in the serum. Dietary arginine quadratically decreased the content of malondialdehyde (MDA) and increased the activity of total superoxide dismutase (T-SOD) (P < 0.05). Dietary arginine supplementation linearly and quadratically increased the contents of immunoglobulin A (IgA) and immunoglobulin G (IgG), and linearly increased the content of nitric oxide (NO) (P < 0.05). In conclusion, dietary arginine supplementation can significantly improve the production performance, serum biochemicals, antioxidant capacity, and immunity of laying Wulong geese. Therefore, 0.3% arginine (actual content: 1.02%) is recommended in the diet.

P210. Effects of dietary arginine supplementation on pig growth performance and health status following weaning stress

P210. Effects of dietary arginine supplementation on pig growth performance and health status following weaning stress

Dietary arginine requirement in diets of GIFT strain of Nile tilapia, Oreochromis niloticus : Effects on growth performance, whole‐body composition, growth‐related gene expression and haemato‐biochemical responses

This study aims to evaluate the effects of dietary arginine supplementation on growth performances, whole-body composition, haemato-biochemical responses and growth-related gene expression in juvenile GIFT tilapia. Five corn-soy-based isonitrogenous (322 g/kg) and isoenergetic (17.4 MJ/kg) diets were formulated to contain graded levels of dietary arginine (14.7, 15.5, 16.4, 17.6 and 18.5 g/kg of diet). Each diet was randomly assigned to triplicate groups of 30 fish (4.4 ± 0.2 g) per experimental unit, which were fed thrice a day (09:00, 13:00 and 17:00 h) for 60 days. Growth performances and feed utilization were improved in fish fed arginine at 16.4 g/kg of diet compared with other dietary treatments. No significant differences were observed in the whole-body proximate composition, amino acid profile and haematological responses of fish fed graded levels of dietary arginine. However, significant interactions were observed in the blood biochemical responses and mRNA expression of MyoD, Myogenin, GH, IGF-1, GHR-1 and Pax7 in fish fed diets with graded levels of arginine, while dietary arginine levels had no effect on the mRNA expression of myostatin and IGF-2. Second-order polynomial regression analysis of weight gain and nitrogen gain against dietary arginine levels indicated that the optimum dietary arginine requirement for maximum growth and feed utilization of juvenile GIFT tilapia was estimated to be 16.7–16.8 g/kg of diet or 51.8–52.2 g/kg of protein.

Effects of dietary arginine supplementation on cytokine‐ and antioxidant‐related gene expressions in common carp ( Cyprinus carpio ) fingerling during ammonia toxicity

This study investigated the effects of dietary arginine supplementation on plasma ammonia and urea levels, and immune- and antioxidant-related gene expressions of common carp (Cyprinus carpio), exposed to ambient ammonia. Fish (10.5 ± 0.74 g) were fed diets containing arginine (0: control diet, 0.25: 0.25Arg and 0.5%: 0.5Arg) for 14 days and then subjected to ammonia exposure for three hours. The results showed that arginine significantly decreased plasma ammonia level, whereas increased the plasma urea level. Arginine supplementation significantly up-regulated head kidney il1b, il10, tnfa and liver sod, cat, gpx and gst gene expressions, whereas significantly down-regulated hsp70 gene expression in liver. Ammonia exposure led to a significant increase in plasma ammonia and urea levels. There were elevations in head kidney il1b, and liver sod, cat, gpx, gst and hsp70 gene expression in fish after challenged with ammonia. The interaction effects of arginine supplementation and ammonia exposure on head kidney il10, and liver gst and hsp70 gene expressions were observed, as arginine prevented ammonia-induced down-regulation in il10 expression, mitigated ammonia-induced up-regulation in hsp70 expression and intensified up-regulation in gst expression. In conclusion, it is suggested that two-week supplementation of arginine (0.5% of diet) is useful to mitigate the adverse effects of ambient ammonia when in the farm, common carp is at risk of ammonia toxicity.

Effects of dietary arginine supplementation on ureagenesis and amino acid metabolism in common carp (Cyprinus carpio) exposed to ambient ammonia

The aim of the present study was to determine the effects of dietary arginine supplementation on resistance and responses to ammonia toxicity in common carp (Cyprinus carpio). In the first experiment, the fish were fed with four diets supplemented with 0% (control diet), 0.25% (0.25Arg), 0.5% (0.5Arg) or 1% (1Arg) for 14 days and challenged with 0.7, 0.8, 0.9, 1.1, 1.3 mg/L water unionized ammonia for 3 h. The results showed that 0.7 mg/L ammonia caused no mortality in the treatments, but 1.3 mg/L ammonia killed all the fish. In the second experiment, the fish fed either the control or the 0.5Arg diet for 14 days and exposed to 0.7 mg/L ammonia for 3 h, and plasma ammonia and free amino acids were determined. The results showed that arginine administration significantly increased plasma arginine, urea, ornithine, glutamate, aspartate and histidine, whereas decreased plasma ammonia, citrulline, glutamine and other amino acids except for glycine, asparagine and serine. Ammonia exposure led to significant elevations in plasma ammonia and urea, and significant declines in plasma arginine, ornithine, citrulline and other amino acids. In conclusion, common carp is ureagenic under ammonia exposure and tries to detoxify ammonia by converting to urea, as well as formation of glutamine. To keep glutamate levels constant during ammonia toxicity, common carp may utilize alanine, aspartate, glycine and serine for α-ketoglutarate formation as a substrate for glutamate synthesis. Arginine administration provides high levels of ornithine, which is used to convert ammonia to urea after ammonia toxicity. The benefits of arginine in common carp resistance to ammonia toxicity seem to be related to its stimulatory effects on ureageneis; however, other health benefits of the amino acid (anti-stress, antioxidant and anti-anemic) should not be neglected.

Effects of dietary arginine supplementation in pregnant mares on maternal metabolism, placental structure and function and foal growth

Foals born to primiparous mares are lighter and less mature than those born to multiparous dams. Factors driving this difference are not totally understood. Using 7 multiparous and 6 primiparous standardbred mares, we demonstrated that, in late gestation, primiparous mares were less insulin resistant compared to multiparous mares, and that their foals had reduced plasma amino-acid concentrations at birth compared to foals born to multiparous mares. Vascular development, as observed through structure and gene expression, and global DNA methylation were also reduced in primiparous placentas. Another group of 8 primiparous mares was orally supplemented with L-arginine (100 g/day, 210d to term). L-arginine improved pregnancy-induced insulin resistance and increased maternal L-arginine and L-ornithine plasma concentrations but foal plasma amino acid concentrations were not affected at birth. At birth, foal weight and placental biometry, structure, ultra-structure and DNA methylation were not modified. Placental expression of genes involved in glucose and fatty acid transfers was increased. In conclusion, maternal insulin resistance in response to pregnancy and placental function are reduced in primiparous pregnancies. Late-gestation L-arginine supplementation may help primiparous mares to metabolically adapt to pregnancy and improve placental function. More work is needed to confirm these effects and ascertain optimal treatment conditions.

Effects of arginine supplementation on growth performance and plasma arginine, ornithine and citrulline dynamics of rainbow trout, Oncorhynchus mykiss

This study aimed to re-evaluate the effect of excessive arginine supplementation on growth and feed efficiency of rainbow trout, and to assess the effect of dietary arginine supplementation on hepatic amino acid composition, expression of arginase Ⅱ (ARG 2), inducible nitric oxide synthase (iNOS), and heat shock protein 70 (HSP70) genes in the intestine, and plasma arginine, ornithine, citrulline and urea levels at 0, 6, 12 and 18 hr-postprandial. Rainbow trout (body weight: 60.5–65 g) were fed diets containing 1.47 (control [CTRL]), 3.89 (3.89A) and 5.64% (5.64A) arginine for nine weeks. Higher muscle protein content was observed in 3.89A than CTRL (p < 0.05). In postprandial study, plasma arginine of 5.64A kept increased until 12 hr-postprandial and reached identical value (around 150 µg/ml) until 18 hr-postprandial in 5.64A. Significant increase of plasma arginine level was only observed in arginine supplemented group. Meanwhile, plasma citrulline level in CTRL was significantly higher than in 5.64A at 18 hr-postprandial. A significantly higher hepatic citrulline level was also observed in CTRL than in 5.64A (p < 0.05). Significantly higher plasma and hepatic free ornithine level was observed in 5.64A than CTRL while significantly higher expression of intestinal ARG2 and HSP70 was found in arginine supplemented groups. These results suggest that citrulline availability seems to be stimulated by arginine deficiency in the CTRL and the presence of arginase in the intestine to regulate excess dietary arginine.

Effects of dietary arginine supplementation on growth, biochemical, and immunological responses of common carp (Cyprinus carpio L.), stressed by stocking density

The present study aimed to investigate interaction effects of dietary arginine and stocking density on common carp (Cyprinus carpio) growth performance, stress response, innate immunity and immune gene expression. Three diets with deficient (4.1% of dietary protein; DA), optimum (5.3% of dietary protein; OA) and surplus (8.1% of dietary protein; SA) arginine levels were formulated. The diets were offered for 30 days to common carp reared at two different stocking densities, 10 or 20 g/L. Then blood leukocyte count, and plasma cortisol, glucose, total protein, globulin, total immunoglobulin (Ig), lysozyme and complement (ACH50), and head kidney interleukin-1 beta (IL-1beta), interleukin-8 (IL-8) and tumor necrosis factor-alpha (TNF-a) were determined. Results showed that increased stocking density led to decreased growth performance; similarly, both DA and SA groups had significantly lower growth performance compared to the OA group. Increased stocking density led to increased plasma cortisol, glucose, lysozyme, proteins and ACH50 and decreased plasma total Ig and blood WBC, and the head kidney’ cytokine genes expression. Both DA and SA groups had significantly higher plasma cortisol and glucose, and lower plasma lysozyme, proteins, ACH50, and head kidney's cytokine gene expression compared to the OA treatment; the SA group had more adverse effects on these parameters than the DA group. Dietary arginine at optimum level significantly inhibited the stress-induced cortisol and lysozyme elevation and mitigated the stress-induced IL-1beta and IL-8 genes down-regulation. In conclusion, dietary arginine deficient or surplus levels significantly impair common carp growth performance and health conditions. Moreover, surplus dietary arginine level has no benefit on the fish growth and health under high stocking density condition.

Effects of Dietary Arginine Supplementation in Pregnant Mares on Maternal Metabolism and Foal Birthweight

Withers height is an important economic trait for the American Miniature Horses (AMHs) as the breeders' primary objective is to produce small and proportionate animals. Identification of Quantitative Trait Loci (QTLs) affecting height in this breed will result in a better understanding of the genetic architecture and biological pathways contributing to skeletal development. In earlier work, we genotyped 48 horses from 16 different breeds that represent extremes in body size, using the Equine SNP50 bead chip (Illumina Inc). In this study, we applied a dominant model Genome-wide association study (GWAS), a genome-wide fixation index (FST) estimation, as well as a cross-population composite likelihood ratio (XP-CLR) test between the eight large and eight small breeds from this data set. Our GWAS implicated the marker at ECA1:37,676,322 bp, positioned within an intron of the ANKRD1 gene, was significantly associated with height variation. An XP-CLR scan further supported a role in height for the ECA1:37,676,322 bp locus and the FST analysis supported correlations to IGF2BP2 at ECA19:23,815,750. To confirm our findings, we genotyped the candidate loci in an independent set of 89 AMHs. This set verified that the locus at ANKRD1 gene indeed correlates to height under a dominant mode of inheritance, but not the locus at the IGF2BP2 gene. ANKRD1, a transcription factor involved in myocyte growth and differentiation, may contribute to height by influencing the overall growth of the horses. This marker will be a valuable tool for the selection of breeding stock in breeds with height restrictions for registration.

Effect of dietary arginine supplementation on body weight changes and productivity of sows

Effect of dietary arginine supplementation on body weight changes and productivity of sows

Dietary arginine supplementation does not improve nutrient utilisation in gilthead seabream

The aim of this study was to evaluate the beneficial effects of dietary arginine supplementation on growth performance, urea biosynthesis, and N excretion of juvenile gilthead sea bream (Sparus aurata) fed fish meal and plant-feedstuffs based diets. For that purpose, five isonitrogenous (45% crude protein) diets were formulated as follows: two diets were fish meal-based and contained 3.0 and 4.0% arginine; three diets were plant feedstuff-based and contained 1.6, 3.0, and 4.0% arginine. Triplicate groups of gilthead seabream juveniles (24g) were fed each diet for 10weeks. At the end of the trial, growth performance of fish fed the fish meal-based diets was higher than that of the other groups. Dietary arginine content did not affect growth performance.Ammonia excretion was not affected by diet composition, while urea excretion was directly related with arginine intake. Carbamyl phosphate synthase activity was not detected in the liver, while arginase activity increased and ornithine carbamyl-transferase decreased with dietary arginine content.Overall, an excess of dietary arginine had no beneficial effects on growth performance and feed utilisation of gilthead seabream juveniles fed plant feedstuffs-based diets. A functional urea cycle was not detected in the liver of gilthead sea bream juveniles.

Arginine for gestating sows and foetal development: A systematic review.

The use of functional amino acids during pregnancy has been linked to improved reproduction in mammals. In this context, arginine is a precursor in the synthesis of numerous molecules, such as nitric oxide and polyamines, which play an important role during reproduction. However, contradictory studies are found in the literature, particularly regarding the amount of supplementation and the period of pregnancy in which it is used. The objective of this study was to evaluate the effects of dietary arginine supplementation for pregnant sows on foetal development via a systematic review. The search for papers was performed during the month of December 2015, in the databases ISI Web of Science, Science Direct, Scopus, and SciELO. From a total of 5675 returned studies, only 13 papers were selected after applying selection criteria. Most (47%) of the studies that evaluated the effects of dietary arginine supplementation on foetal development in pigs used 1% arginine. Supplementation was initiated in the first third of pregnancy in 47% of tests, including in both primiparous and multiparous sows. These studies showed positive results for embryo survival and foetal development, evidenced by the increase in placental weight and the number and weight of piglets born alive. Of all evaluated studies, 53% showed benefits on foetal development. It is concluded that supplementing dietary arginine in gestating sows can benefit embryo survival and foetal development. However, to establish a supplementation plan with this amino acid, aspects related to the period of pregnancy, supplementation levels, and source of arginine must be well defined.

Arginine: New Insights into Growth Performance and Urinary Metabolomic Profiles of Rats.

Arginine regulates growth performance, nutrient metabolism and health effects, but the underlying mechanism remains unknown. This study aims to investigate the effect of dietary arginine supplementation on rat growth performance and urinary metabolome through 1H-NMR spectroscopy. Twenty rats were randomly assigned to two groups supplemented with 0% or 1.0% l-arginine for 4 weeks. Urine samples were analyzed through NMR-based metabolomics. Arginine supplementation significantly increased the urine levels of 4-aminohippurate, acetate, creatine, creatinine, ethanolamine, formate, hippurate, homogentisate, indoxyl sulfate, and phenylacetyglycine. Conversely, arginine decreased the urine levels of acetamide, β-glucose, cirtulline, ethanol, glycine, isobutyrate, lactate, malonate, methymalonate, N-acetylglutamate, N-methylnicotinamide, and propionate. Results suggested that arginine can alter common systemic metabolic processes, including energy metabolism, amino acid metabolism, and gut microbiota metabolism. Moreover, the results also imply a possible physiological role of the metabolism in mediating the arginine supplementation-supported growth of rats.

アルギニンの給与が黒毛和種肥育去勢牛の血液生化学検査成績に及ぼす影響

アルギニンの給与が黒毛和種肥育去勢牛の血液生化学検査成績に及ぼす影響

Effects of arginine supplementation during early gestation (day 1 to 30) on litter size and plasma metabolites in gilts and sows.

Two experiments were conducted, under typical commercial swine production conditions, to determine effects of dietary arginine supplementation during early gestation on the performance of gilts and sows. In Exp. 1, between d 1 and 30 of gestation, 62 Landrace gilts and 113 sows consumed a corn- and soybean meal-based diet supplemented with 1.3% -arginine HCl or 2.2% -alanine. Total numbers of piglets born ( < 0.05) and born alive ( < 0.01) per litter and litter birth weights of piglets born ( < 0.05) and born alive ( < 0.05) were increased in the arginine group compared with the control. In Exp. 2, 155 multiparous Landrace sows received 1.3% -arginine HCl supplementation between d 1 and 14 (T2; = 41), d 15 and 30 (T3; = 40), or d 1 and 30 (T4; = 37), whereas the control group received 2.2% -alanine supplementation between d 1 and 30 (T1; = 37). Blood samples were randomly obtained from 6 sows per group on d 1, 14, and 28 of gestation to determine plasma concentrations of AA and related metabolites. Total numbers of piglets born ( = 0.084) and born alive ( = 0.080) per litter tended to be higher for sows supplemented with arginine between d 1 and 14 of gestation (T2) than for control sows (T1). Concentrations of arginine and nitric oxide metabolites were greater ( < 0.05) in T4 compared with T1 and T3 on d 14 of gestation and were also greater in T4 compared with T1 and T2 on d 28 of gestation. Plasma concentrations of spermidine ( < 0.001) were increased in T3 and T4 compared with T1 and T2 on d 28. These results indicate that dietary arginine supplementation during early gestation improves the reproductive performance of gilts and sows, possibly via nitric oxide and polyamine-dependent mechanisms.

Effects of dietary arginine supplementation on growth performance, flesh quality, muscle antioxidant capacity and antioxidant-related signalling molecule expression in young grass carp (Ctenopharyngodon idella)

Growth performance, flesh quality, antioxidant status and antioxidant-related signalling molecule expression in the muscle of young grass carp, which were fed graded levels of arginine (6.9–24.5g/kg diet) for eight weeks, were investigated. Muscle protein, lipid and nitric oxide contents, shear force, hydroxyproline concentration, and pH were significantly improved by appropriate arginine. Cooking loss, lactate content, cathepsins activities, malondialdehyde and protein carbonyl contents exhibited an opposite tendency. Additionally, optimum arginine significantly enhanced glutathione content and the activities and gene expression of copper/zinc superoxide dismutase, catalase and glutathione peroxidase in muscle. Moreover, the expression levels of glutamate–cysteine ligase, target of rapamycin, ribosome protein S6 kinase 1, casein kinase 2 and NF-E2-related factor 2 in muscle were significantly elevated by appropriate arginine. However, optimum arginine significantly decreased Kelch-like ECH-associated protein 1 mRNA levels in muscle. In conclusion, arginine improved the flesh quality and muscle antioxidant capacity and regulated antioxidant-related signalling molecule expression.

English

Young piglets have a high requirement of arginine for growth and metabolic function, but the sow milk or endogenous synthesis cannot provide enough arginine for maximal growth. Dietary Arginine supplementation can improve the immunity of early-weaned piglets and enhance the skeletal muscle synthesis for growth. The insulin-like growth factor (IGF) signaling pathway is an important regulatory factor in regulating fetal and placental growth, proliferation, differentiation, migration and aggregation, and inhibits apoptosis of mammalian cells. However, how the insulin-like growth factor system expression altered in piglets with dietary arginine supplementation, and whether arginine plays a role in IGF system secretion is little noticed. This study was conducted to investigate the effect of dietary arginine supplementation in modulation IGF system of weanling piglets. Twelve 21-day-old healthy piglets (Landrace&times;Yorkshire) with a mean body weight (BW) were assigned randomly to two treatments representing diets supplemented with 0.6% L-arginine and 1.23% L-alanine (isonitrogenous control). At 28 days of age, 12 piglets were killed and longissimus muscle, liver and kidney were collected. Components of IGF signaling pathway mRNA expression were examined in three tissues, IGF1 was increased in three tissues of arginine group (P&lt;0.05). IGF2 was increased in muscle of arginine group. Both muscle and liver had a higher level of IGFBP5 with arginine supplementation (P&lt;0.05). These data suggest an important role of arginine in modulation of IGF signal pathway and the involvement of IGF and IGF receptors in the improved growth performance. &nbsp; Key words:&nbsp;L-Arginine, IGFs, early-weaned piglets.

Effects of dietary arginine supplementation on reproductive performance and immunity of sows

Arginine (Arg) is considered to have beneficial effects on placental development and function, as well as reproductive performance. The well-developed placenta is highly required in late gestation for rapid fetal growth, however, it is unknown if there is a crucial role of Arg in late gestation. Likewise, the immunological response of sows to Arg needs to be determined. Therefore, this study is designed to investigate the effects of dietary Arg supplementation on reproductive performance and immunity of sows. At day 30 of gestation, sixty sows (Landrace &amp;times; Large White) were allocated to 3 groups receiving corn and soybean-based control diet (control group, n = 20), control diet supplemented with 1% l-arginine HCl until day 90 of gestation (Arg90 group, n = 20), and control diet supplemented with 1% l-arginine HCl until day 114 of gestation (Arg114 group, n = 20), respectively. Litter performance was recorded at parturition. Blood samples (n = 6) collected at days 30, 90, and 110 of gestation were measured for metabolic and immunological parameters. At parturition, total litter size was not affected by dietary Arg supplementation. As a result of less pigs born dead, however, sows in Arg114 group had more pigs born alive than sows in control group (+1.6 pigs, P &amp;lt; 0.05), total and live litter weights were increased (+1.6~2.1 kg, P &amp;lt; 0.05) in Arg114 group relative to both control and Arg90 groups. Compared with control group, dietary Arg supplementation increased (+12~110%, P &amp;lt; 0.05) plasma levels of ornithine, proline, and arginine at either day 90 (Arg90 and Arg110 groups) or day 110 of gestation (Arg110 group). Moreover, immune response was enhanced in Arg-supplemented sows, as indicated by the increased levels of serum immunoglobulin and porcine reproductive and respiratory syndrome virus (PRRSV) antibody. These findings indicate dietary Arg supplementation can improve litter performance and immune response, and the beneficial effect of Arg on fetal growth is evident in late gestation.