Dietary Arg Supplementation Research Articles

Effects of increasing dietary arginine supply during the three first weeks after weaning on pig growth performance, plasma amino acid concentrations, and health status.

A total of 425 weaned pigs (Exp. 1: 225 pigs [5.8 ± 0.9 kg]; Exp. 2: 200 pigs [6.1 ± 1.2 kg]) were used to determine the optimal dietary standardized ileal digestible (SID) arginine (Arg) level in early nursery diets based on growth and health responses. The basal diet in Exp.1 was formulated to meet SID Arg recommendation (0.66%; NRC, 2012) and in Exp. 2, SID Arg was set to simulate current industry practices for feeding nursery pigs (1.15 %). Basal diets were supplemented with 0.3%, 0.6%, 0.9%, and 1.2% of l-arginine to provide five levels of dietary SID Arg. Experimental diets were fed during phases I (days 0 to 7) and II (days 8 to 21) with common diets until market. Feed disappearance and body weight (BW) were measured on days 7, 14, 21, and 43. Final BW was recorded at first removal of pigs for market. Pen fecal score was assigned daily from days 0 to 21. Plasma immunoglobulin A (IgA) was determined on days 0, 7, and 14 and amino acids (AAs) concentration and plasma urea nitrogen (PUN) on days 0 and 14. Orthogonal polynomial contrasts were used to determine the linear and quadratic effects of dietary Arg. Optimal SID Arg was determined by fitting the data with piecewise regression, using growth performance as the primary response variable. In Exp. 1, dietary Arg linearly increased (P < 0.1) BW, average daily gain (ADG), and gain to feed ratio (G:F) ratio on day 21, as well as reduced (χ2 = 0.004) the percentage of pigs that lost weight (PLW) in week 1 by 29%. Dietary Arg resulted in linear improvement (P = 0.082) of ADG for the overall nursery period and quadratic improvement (P < 0.1) of final BW at marketing. In Exp. 2, dietary Arg linearly increased (P < 0.05) ADG and average daily feed intake (ADFI) in week 1, BW and ADFI (P < 0.1) on day 14, as well as reduced (χ2 ≤ 0.001) PLW in week 1. From days 0 to 21, G:F was improved quadratically (P < 0.1). Dietary Arg linearly increased (P < 0.1) ADG and BW on day 43. Dietary Arg supplementation decreased the incidence (χ2 < 0.05) of soft and watery feces during the first weeks after weaning and lower concentration of plasma IgA on days 7 and 14. Dietary Arg linearly and/or quadratically influenced plasma AA concentrations (P < 0.05), including an increase in Arg, Leu, Phe, Val, citrulline, ornithine, and PUN concentrations. Overall, weaned pigs exhibit optimal nursery growth performance and health when provided with dietary SID Arg ranging from 1.5% to 1.9%. This dietary range contributes to a reduction in the occurrence of fall-back pigs and improvements in final BW at marketing.

Impact of dietary supplementation of l-Arginine, l-Glutamine, and the combination of both on nursing performance of multiparous sows.

Dietary supplementation with arginine (Arg) or glutamine (Gln) has been considered as an option to improve nursing performance in reproductive sows. This study investigated whether a low-level supplementation of Arg or Gln or a blend of both could modify milk nutrients and improve piglets' growth beyond weaning. Seventy-two multiparous sows were assigned to four groups: one group fed a control diet, three treatment groups fed the control diet supplemented with either 0.35% Arg, 0.35% Gln, or both, from day 108 of gestation until weaning at day 26 of lactation. Immediately after birth, the litters were cross fostered to 13 piglets and monitored until 2 wk after weaning. Sows body condition and litter growth were assessed. Colostrum and milk samples were collected for nutrient analyses. Plasma concentrations of insulin-like growth factor 1 (IGF-1) around weaning were determined in sows and two representative piglets per litter. Supplementing Gln or the combination of Arg and Gln had no effect on the parameters studied. Arg supplementation increased weaning weight, while decreasing the variation of piglet weights 2 wk after weaning. There was no correlation with plasma IGF-1 since the hormone was not altered in sows or piglets. The colostral concentration of fat tended to increase in the Arg-group, whereas protein, lactose, energy, and polyamine concentrations remained unaffected. Milk samples obtained on day 12 and 25 of lactation were not influenced by dietary treatment. The data indicate that there might be a window of opportunity, explicitly at the onset of lactation, for dietary intervention by maternal dietary Arg supplementation.

Dietary N-carbamylglutamate and L-arginine supplementation improves redox status and suppresses apoptosis in the colon of intrauterine growth-retarded suckling lambs.

Previous studies have revealed that dietary N-carbamylglutamate (NCG) or L-arginine (Arg) improves small intestinal integrity and immune function in suckling Hu lambs that have experienced intrauterine growth retardation (IUGR). Whether these nutrients alter redox status and apoptosis in the colon of IUGR lambs is still unknown. This study, therefore, aimed at investigating whether dietary supplementation of Arg or NCG alters colonic redox status, apoptosis and endoplasmic reticulum (ER) stress and the underlying mechanism of these alterations in IUGR suckling Hu lambs. Forty-eight 7-d old Hu lambs, including 12 with normal birth weight (4.25±0.14kg) and 36 with IUGR (3.01±0.12kg), were assigned to 4 treatment groups (n=12 each; 6 males and 6 females) for 3 weeks. The treatment groups were control (CON), IUGR, IUGR+Arg and IUGR+NCG. Relative to IUGR lambs, superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) content, as well as proliferation index, were higher (P<0.05) whereas reactive oxygen species (ROS), malondialdehyde (MDA) levels and apoptotic cell numbers were lower (P<0.05) in colonic tissue for both IUGR+Arg and NCG lambs. Both mRNA and protein levels of C/EBP homologous protein 10 (CHOP10), B-cell lymphoma/leukaemia 2 (Bcl-2) -associated X protein (Bax), apoptosis antigen 1 (Fas), activating transcription factor 6 (ATF6), caspase 3, and glucose-regulated protein 78 (GRP78) were lower (P<0.05) while glutathione peroxidase 1 (GPx1), Bcl-2 and catalase (CAT) levels were higher (P<0.05) in colonic tissue for IUGR+Arg and IUGR+NCG lambs compared with IUGR lambs. Based on our results, dietary NCG or Arg supplementation can improve colonic redox status and suppress apoptosis via death receptor-dependent, mitochondrial and ER stress pathways in IUGR suckling lambs.

Dietary L-Arginine or N-Carbamylglutamate Alleviates Colonic Barrier Injury, Oxidative Stress, and Inflammation by Modulation of Intestinal Microbiota in Intrauterine Growth-Retarded Suckling Lambs.

Our previous studies have revealed that dietary N-carbamylglutamate (NCG) and L-arginine (Arg) supplementation improves redox status and suppresses apoptosis in the colon of suckling Hu lambs with intrauterine growth retardation (IUGR). However, no studies have reported the function of Arg or NCG in the colonic microbial communities, barrier function, and inflammation in IUGR-suckling lambs. This work aimed to further investigate how dietary Arg or NCG influences the microbiota, barrier function, and inflammation in the colon of IUGR lambs. Forty-eight newborn Hu lambs of 7 d old were assigned to four treatment groups (n = 12 per group; six male, six female) as follows: CON (normal birth weight, 4.25 ± 0.14 kg), IUGR (3.01 ± 0.12 kg), IUGR + Arg (2.99 ± 0.13 kg), and IUGR + NCG (3.03 ± 0.11 kg). A total of 1% Arg or 0.1% NCG was supplemented in a basal diet of milk replacer, respectively. Lambs were fed the milk replacer for 21 d until 28 d after birth. Compared to the non-supplemented IUGR lambs, the transepithelial electrical resistance (TER) was higher, while fluorescein isothiocyanate dextran 4 kDa (FD4) was lower in the colon of the NCG- or Arg-supplemented IUGR lambs (p &lt; 0.05). The IUGR lambs exhibited higher (p &lt; 0.05) colonic interleukin (IL)-6, IL-1β, tumor necrosis factor (TNF)-α, reactive oxygen species (ROS), and malondialdehyde (MDA) levels than the CON lambs; the detrimental effects of IUGR on colonic proinflammatory cytokine concentrations and redox status were counteracted by dietary Arg or NCG supplementation. Both IUGR + Arg and IUGR + NCG lambs exhibited an elevated protein and mRNA expression of Occludin, Claudin-1, and zonula occludens-1 (ZO-1) compared to the IUGR lambs (p &lt; 0.05). Additionally, the lipopolysaccharide (LPS) concentration was decreased while the levels of acetate, butyrate, and propionate were increased in IUGR + Arg and IUGR + NCG lambs compared to the IUGR lambs (p &lt; 0.05). The relative abundance of Clostridium, Lactobacillus, and Streptococcus was lower in the colonic mucosa of the IUGR lambs than in the CON lambs (p &lt; 0.05) but was restored upon the dietary supplementation of Arg or NCG to the IUGR lambs (p &lt; 0.05). Both Arg and NCG can alleviate colonic barrier injury, oxidative stress (OS), and inflammation by the modulation of colonic microbiota in IUGR-suckling lambs. This work contributes to improving knowledge about the crosstalk among gut microbiota, immunity, OS, and barrier function and emphasizes the potential of Arg or NCG in health enhancement as feed additives in the early life nutrition of ruminants.

Effects of dietary arginine in ameliorating the deleterious effects induced by mycotoxins on growth, immune system, body organs in growing pigs.

Mycotoxin contamination in pig feeds has a negative impact on growth performance, the immune system, and major body organs. Arginine (Arg) plays an important role in animals’ body biochemistry and physiology. This study aimed to determine the effect of dietary Arg supplementation on mitigating the negative effects of mycotoxins in growing pigs. A total of 72 growing pigs (Landrace × Large white) with initial mean body weight (BW) = 55 ± 2.5 kg were allotted to four treatment groups with three replicates per group of six pigs per replicate in a completely randomized design. The treatments included a non-toxin diet with 1.2% Arg (NT1.2) and mycotoxin-challenged treatments supplemented with 1.2% Arg (TX1.2), 1.3% Arg (TX1.3), and 1.4% Arg (TX1.4). Statistical analysis of data included the effects of dietary level of Arg. The results indicated a significantly higher BW (p < 0.05), average daily gain (p < 0.05), and gain-to-feed ratio (p < 0.05) in the NT1.2 group than in the TX1.2, TX1.3, and TX1.4 groups. The relative weight of the liver was higher (p < 0.05) in the TX1.2 compared to that of the NT1.2 group, although it was not different from that of TX1.3 and TX1.4. The level of tumor necrosis factor-alpha was significantly up-regulated (p < 0.05) in the liver tissue of the TX1.2 group compared to that of the other treatments. Overall, dietary Arg supplementation remedied liver injury and alleviated the compromised immune system caused by mycotoxin toxicity.

Dietary L-arginine supplementation during days 14-25 of gestation enhances aquaporin expression in the placentae and endometria of gestating gilts.

This study tested the hypothesis that dietaryL-arginine (Arg) supplementation to pregnant gilts enhanced theexpression of water channel proteins [aquaporins (AQPs)] in their placentae and endometria. Gilts were fed twice daily 1kg of a corn and soybean meal-based diet supplemented with 0.0%, 0.4%, or 0.8% Arg between Days 14 and 25 of gestation. On Days 25 and 60 of gestation, gilts were hysterectomized to obtain placentae and endometria. On Day 25 of gestation, supplementation with 0.4% Arg increased (P < 0.05) the abundance of placental AQP9 protein, whereas supplementation with 0.8% Arg increased (P < 0.05) placental AQP1 and AQP9 proteins, compared with controls. On Day 60 of gestation, supplementation with 0.4% Arg increased (P < 0.05) endometrial AQP1 protein, whereas supplementation with 0.8% Arg increased (P < 0.05) endometrial AQP5 and AQP9 proteins. Supplementation with 0.8% Arg increased the endometrial expression of AQP1, AQP5, and AQP9 proteins located in the luminal epithelium and glandular epithelium of endometria, and placental transport of 3H2O. Collectively, these results indicate that dietary Arg supplementation stimulates theexpression of selective AQPs in porcine placenta and endometria, thereby enhancing water transport from mother to fetus and expanding the chorioallantoic membranes during the period of placentation.

Impact of arginine supplementation on serum prolactin and mRNA abundance of amino acid transporter genes in mammary tissue of lactating sows.

This study was conducted to test the hypothesis that supplemental dietary Arg to late-pregnant and lactating sows increases serum prolactin concentrations and mRNA abundance of SLC7A1, SLC7A2, and SLC6A14 in mammary parenchymal tissue. From day 108 of gestation and until day 21 of lactation, sows were fed a diet either supplemented with 0.10 g of l-Arg/kg body weight (BW) per day (n = 10, ARG) or 0.34 g of l-Glu/kg BW per day (n = 10, control). Litters were standardized to 10 piglets on day 1 of lactation and piglets were weighed on days 1, 7, 14, and 21 of lactation. Sow BW was recorded on day 108 of gestation and days 1, 10, and 21 of lactation. Lactation sow feed intake was recorded daily. Mammary parenchymal tissue was biopsied on day 5 of lactation to measure mRNA abundance SLC7A1, SLC7A2, and SLC6A14. On days 4 and 18 of lactation, blood samples were collected from sows at 2, 4, and 6 hr postfeeding to measure serum prolactin concentrations. Milk samples were collected on days 4, 10, and 18 of lactation to measure fat, lactose, urea N, and true protein concentrations. Sow BW, backfat, and feed intake over all sampling days did not differ between treatments. Piglet BW on d 1 tended to be greater for the ARG treatment than the control treatment (P = 0.12). Sow milk yield and composition (fat, protein, lactose, and urea N) and mammary mRNA abundance of candidate genes did not differ between the ARG and the control group. Compared to controls, serum prolactin concentrations tended to be greater (P = 0.08) in ARG sows on day 4 of lactation, and did not differ on day 18. Current findings show a potential beneficial effect of dietary supplementation with Arg to late-pregnant multiparous sows on BW of their piglets on day 1. Dietary Arg supplementation at a rate of 0.10 g/kg BW during late pregnancy and lactation tended to increase serum prolactin concentrations with no increase in mammary transcript abundance of SLC7A1, SLC7A2, and SLC6A14 in early lactation.

Arginine supplementation in plant‐rich diets affects growth, feed utilization, body composition, blood biochemical indices and gene expressions of the target of rapamycin signaling pathway in juvenile Asian red‐tailed catfish (Hemibagrus wyckoiides)

AbstractArginine (Arg) is an important essential amino acid required for optimum fish growth. However, its role in plant‐rich diets on growth and the required level in juvenile Hemibagrus wyckioides are currently unknown. This study evaluated the effects of Arg supplementation in plant‐rich diets on growth, feed utilization, whole body composition, blood biochemical indicators and gene expressions of the target of rapamycin (TOR) signaling pathway in juvenile H. wyckioides. A total of 450 fish (6.40 ± 0.06 g) were randomized into six equal groups and fed on diets with graded Arg levels: 0 (control), 3, 6, 9, 12 and 15 g/kg of dry feed for eight weeks. The results revealed that specific growth rate (SGR) and feed conversion ratio of juvenile H. wyckioides were significantly improved and reduced, respectively in fish fed on 9 g/kg of Arg supplementation (p &lt; .05). The optimum amount of dietary Arg content in plant‐rich diets for H. wyckioides was 63.77 g/kg diet based on SGR. Feeding fish with dietary Arg supplementation ranging from 9 to 12 g/kg improved significantly (p &lt; .05) whole body protein contents and decreased lipid deposition. The mRNA levels of TOR, eukaryotic translation initiation factor 4E (4EBP) and ribosomal protein S6 kinase 1 (S6K1) in muscle and liver were significantly affected by increasing dietary Arg levels. Meanwhile, the mRNA relative expression levels of TOR and S6K1 in the liver and muscle increased significantly as Arg supplementation increased. On the other hand, the mRNA relative expression levels of 4EBP was significantly higher in fish fed on the 9 g/kg Arg diet compared to those fed on the control and 15 g/kg Arg diets. In conclusion, our current results indicate that dietary Arg supplementation in plant‐rich diets, might activate the TOR signaling pathway, which promotes protein synthesis and reduces lipid accumulation of H. wyckioides, resulting in improved growth.

Dietary Arginine Regulates Severity of Experimental Colitis and Affects the Colonic Microbiome.

There is great interest in safe and effective alternative therapies that could benefit patients with inflammatory bowel diseases (IBD). L-arginine (Arg) is a semi-essential amino acid with a variety of physiological effects. In this context, our aim was to investigate the role of dietary Arg in experimental colitis. We used two models of colitis in C57BL/6 mice, the dextran sulfate sodium (DSS) model of injury and repair, and Citrobacter rodentium infection. Animals were given diets containing (1) no Arg (Arg0), 6.4 g/kg (ArgNL), or 24.6 g/kg Arg (ArgHIGH); or (2) the amino acids downstream of Arg: 28 g/kg L-ornithine (OrnHIGH) or 72 g/kg L-proline (ProHIGH). Mice with DSS colitis receiving the ArgHIGH diet had increased levels of Arg, Orn, and Pro in the colon and improved body weight loss, colon length shortening, and histological injury compared to ArgNL and Arg0 diets. Histology was improved in the ArgNL vs. Arg0 group. OrnHIGH or ProHIGH diets did not provide protection. Reduction in colitis with ArgHIGH diet also occurred in C. rodentium-infected mice. Diversity of the intestinal microbiota was significantly enhanced in mice on the ArgHIGH diet compared to the ArgNL or Arg0 diets, with increased abundance of Bacteroidetes and decreased Verrucomicrobia. In conclusion, dietary supplementation of Arg is protective in colitis models. This may occur by restoring overall microbial diversity and Bacteroidetes prevalence. Our data provide a rationale for Arg as an adjunctive therapy in IBD.

Effects of replacing fish meal with soybean meal, with or without dietary arginine, on growth performance, immune indices and intestinal morphology of grouper, Epinephelus malabaricus

A 10-week feeding experiment was conducted to evaluate the effects of replacing fish meal with soybean meal (SBM), with or without dietary arginine (Arg), on growth performance, immune indices and intestinal morphology of grouper, Epinephelus malabaricus. Nine experimental diets were formulated to contain 20%, 30% and 40% fish meal protein (FMP) replaced using SBM and 0, 0.5% and 1% dietary Arg supplementation. The results showed that weight gain (WG) of fish was significantly affected by the interaction of substitution level and Arg supplemental level. The maximum WG occurred at the 30% FMP substitution level and the 0.5% Arg supplemental level. The immune assay showed that the interaction between the two levels significantly influenced the production of serum nitric oxide but did not affect serum IgG concentration and alkaline phosphatase activity or the liver IGF-1 gene expression. Significant interaction effects between the two levels were observed in muscle layer thickness (tML) and fold height (hF) in the proximal and mid-intestine. High SBM level in diets reduced the tML and hF in the entire intestine. The results suggested that the interaction of 30% FMP substitution level and Arg supplemental level of 0.5% most benefitted growth performance, immune indices and intestinal structure of grouper.

Safety of dietary supplementation with arginine in adult humans.

Previous studies with animals and humans have shown beneficial effects of dietary supplementation with L-arginine (Arg) on reducing white fat and improving health. At present, a long-term safe level of Arg administration to adult humans is unknown. The objective of this study was to conduct a randomized, placebo-controlled, clinical trial to evaluate the safety and tolerability of oral Arg in overweight or obese but otherwise healthy adults with a body mass index of ≥ 25kg/m2. A total of 142 subjects completed a 7-day wash-in period using a 12g Arg/day dose. All the remaining eligible 101 subjects who tolerated the wash-in dose (45 men and 56 women) were assigned randomly to ingest 0, 15 or 30g Arg (as pharmaceutical-grade Arg-HCl) per day for 90days. Arg was taken daily in at least two divided doses by mixing with a flavored beverage. At Days 0 and 90, blood pressures of study subjects were recorded,their physical examinations were performed, andtheirblood and 24-h urine samples were obtained to measure: (1) serum concentrations of amino acids, glucose, fatty acids, and related metabolites; and (2) renal, hepatic, endocrine and metabolic parameters. Our results indicate that the serum concentration of Arg in men or women increased (P < 0.05) progressively with increasing oral Arg doses from 0 to 30g/day. Dietary supplementation with 30g Arg/day reduced (P < 0.05) systolic blood pressure and serum glucose concentration in females, as well as serum concentrations of free fatty acids in both males and females. Based on physiological and biochemical variables, study subjects tolerated oral administration of 15 and 30g Arg/day without adverse events. We conclude that a long-term safe level of dietary Arg supplementation is at least 30g/day in adult humans.

Impacts of maternal dietary protein intake on fetal survival, growth, and development.

Maternal nutrition during gestation, especially dietary protein intake, is a key determinant in embryonic survival, growth, and development. Low maternal dietary protein intake can cause embryonic losses, intra-uterine growth restriction, and reduced postnatal growth due to a deficiency in specific amino acids that are important for cell metabolism and function. Of note, high maternal dietary protein intake can also result in intra-uterine growth restriction and embryonic death, due to amino acid excesses, as well as the toxicity of ammonia, homocysteine, and H2S that are generated from amino acid catabolism. Maternal protein nutrition has a pronounced impact on fetal programming and alters the expression of genes in the fetal genome. As a precursor to the synthesis of molecules (e.g. nitric oxide, polyamines, and creatine) with cell signaling and metabolic functions, L-arginine (Arg) is essential during pregnancy for growth and development of the conceptus. With inadequate maternal dietary protein intake, Arg and other important amino acids are deficient in mother and fetus. Dietary supplementation of Arg during gestation has been effective in improving embryonic survival and development of the conceptus in many species, including humans, pigs, sheep, mice, and rats. Both the balance among amino acids and their quantity are critical for healthy pregnancies and offspring. Impact statement This review aims at: highlighting adverse effects of elevated levels of ammonia in mother or fetus on embryonic/fetal survival, growth, and development; helping nutritionists and practitioners to understand the mechanisms whereby elevated levels of ammonia in mother or fetus results in embryonic/fetal death, growth restriction, and developmental abnormalities; and bringing, into the attention of nutritionists and practitioners, the problems of excess or inadequate dietary intake of protein or amino acids on pregnancy outcomes in animals and humans. The article provides new, effective means to improve embryonic/fetal survival and growth in mammals.

Glutamine and arginine in diets for Nile tilapia: Effects on growth, innate immune responses, plasma amino acid profiles and whole-body composition

Glutamine (Gln) and arginine (Arg) are functional amino acids (AA) known to improve growth, immunity and nutrient utilization of animals. Juvenile Nile tilapia were fed six experimental diets formulated to contain different levels of supplemental Gln and/or Arg (Control, GLN 1%, GLN 2%, ARG 1%, ARG 2% and GLN+ARG 1%) for a 9-week period. Growth performance, innate immune responses, AA profiles in plasma and whole-body were examined. Dietary Gln and/or Arg supplementation resulted in significant effects on weight gain, feed intake, feed efficiency, protein efficiency and protein retention. Moreover, the concentration of free AAs in plasma at 6h and 18h were significantly affected by experimental diets. The AA concentrations significantly affected at the 6h sampling were Cys, Asp, Ser, Gly and Hyp while at 18h, differences were observed for Arg, Val, Cys, Ser, Gly and Pro. In contrast, only differences in Gln, Gly and Ser concentrations were observed regarding AA composition of the whole-body tissues. Therefore, the AA profiles of plasma were more affected by the dietary GLN and/or ARG supplementation than whole-body. Most of the immunity indicators were not raised by dietary levels of Gln and/or Arg probably as a reflection of the non-activated state of the immune cells. Although Gly was included to the experimental diets to adjust nitrogen content, this inclusion resulted in effects on the growth performance and physiological parameters. Finally, Nile tilapia fed the combined supplement of GLN+ARG at 1% had more improved growth performance than those fed the diets supplemented individually with Gln or Arg.

Effect of dietary supplementation with arginine on haematological indices, serum chemistry, carcass yield, gut microflora, and lymphoid organs of growing turkeys

A 8-wk feeding experiment was conducted to investigate the effect of dietary supplementation with Arg on haematological indices, serum chemistry, carcass yield, gut microflora, and lymphoid organ weights of growing turkeys. A total of one hundred and eighty 56-d-old male grower turkeys were weighed individually and randomly assigned to 1 of 3 dietary treatments with 6 replicate pens, and 10 turkeys per pen in a completely randomized design. Dietary treatments consisted of basal diets supplemented with 0, 0.5, and 1.0g Arg/kg. Haematological indices and serum chemistry were measured at 84 and 112 d of study. Carcass yield, relative weights of retail cuts, organ weights, and gut microflora were measured at d 112. Except eosinophil, no effect of Arg supplementation was obtained on haematological indices at d 84. At d 112, finisher turkeys fed the diet supplemented with 0.5g Arg/kg had the greatest red blood cell (quadratic, P<0.001), lymphocyte (linear, P=0.011; quadratic, P<0.001), and basophil counts (quadratic, P<0.001). In grower turkeys at d 84, total serum protein (quadratic, P=0.030), and serum globulin concentrations (quadratic, P=0.043) increased initially as Arg supplementation increased from 0 to 0.5g/kg, but decreased with the 1.0g Arg/kg. Uric acid concentration and alanine aminotransferase activity reduced as Arg supplementation increased from 0 to 0.5g/kg, but increased with the 1.0gArg/kg (quadratic, P=0.002). In finisher turkeys at d 112, total serum protein (linear, P=0.004; quadratic, P=0.002), serum globulin (linear, P=0.008; quadratic, P=0.030), serum albumin (linear, P=0.012; quadratic, P=0.040), and triodosterine concentrations (linear, P=0.025; quadratic, P=0.033) increased with increasing Arg supplementation. At d 112, spleen weights increased linearly (P=0.006), while thymus weights increased quadratically (P=0.003) with increasing dietary Arg supplementation. Salmonella counts in the small intestinal content of turkeys at d 112 reduced quadratically as Arg supplementation increased from 0 to 1.0g/kg (P=0.029). In conclusion, Arg supplementation increased packed cell volume of finisher turkeys, improved serum chemistry of grower, and finisher turkeys as indicated by increased total serum protein, and reduced serum enzymes with appreciable improvement obtained when included at 0.5gArg/kg. Arginine supplementation enhanced the relative weights of thymus, spleen, and reduced Salmonella counts in small intestine of turkeys.

Increase in dietary arginine level could ameliorate detrimental impacts of coccidial infection in broiler chickens

The present study was conducted to investigate the effect of dietary supplementation of Arg on growth performance, carcass characteristics, and morphological indices of jejunal epithelial cells in coccidia-challenged broiler chickens. A total of 288 one-day-old broiler chickens were randomly distributed among 3 experimental treatments with 8 replicate pens of 12 broiler chickens each. Experimental treatments consisted of the graded levels of dietary Arg (100, 105, and 110% of the standard recommendations during different growth periods). From 16 to 20 d of age, half of the replicate pens of each dietary Arg level were orally challenged with a mixture of Eimeria species (acervulina, tenella, maxima, and necatrix). Results showed that dietary Arg had no marked effect on average daily feed intake (ADFI) and gain (ADG) during the starter (0 to 14 d of age) and grower (14 to 28 d of age) periods. Although ADFI wasn’t affected by coccidial challenge, ADG of Eimeria-challenged broiler chickens were lower (P<0.05) than those of uninfected ones during both grower and finisher periods. Dietary supplementation of 105 and 110% of Arg, however, prevented depressed ADG in coccidia-infected broiler chickens during the finisher period (28 to 42 d of age) compared with 100% of Arg (Arg×coccidiosis, P<0.05). Coccidial challenge increased (P<0.01) feed conversion ratio (FCR), while 110% of Arg supplementation improved (P<0.05) FCR values during both grower and finisher periods. Although coccidial challenge increased FCR value in control broiler chickens (100% of Arg), dietary Arg supplementation of 105 and 110% improved FCR values during the grower period, resulted in an Arg×coccidiosis interaction (P<0.01). Subjecting the broiler chickens to coccidiosis reduced liver weight (P<0.001) and carcass yield (P<0.05). Dietary Arg supplementation increased (P<0.001) villi height (VH) to crypt depth (CD) ratio. On the other hand, both VH and VH to CD ratio were decreased (P<0.001) in coccidial-infected broiler chickens. Although subjecting the broiler chickens to coccidiosis increased (P<0.001) muscular layer thickness (MLT) of jejunum, supplemental Arg of 110% resulted in a decrease (P<0.01) in jejunal MLT. In addition, supplemental Arg reduced (P<0.05) fecal oocyst count, with the lowest count assigned to the broiler chickens fed 110% of Arg. Dietary Arg supplementation of 110% improved morphological indices in coccidia-challenged broiler chickens, while it had no obvious impact in untreated ones, resulted in the Arg×coccidiosis interactions (P<0.05). The present findings showed that supplementing the diets with Arg above the recommended values could ameliorate negative effects of Eimeria on growth performance and morphological indices of broiler chickens.

Regulatory effects of dietary L-Arg supplementation on the innate immunity and antioxidant ability in broiler chickens

Here, we investigated the effect of dietary arginine (Arg) supplementation on innate immunity and the antioxidant ability of broiler chickens. The experiment was designed as a single-factorial arrangement (n=8 cages/treatment, six birds/cage), and we used four dietary Arg concentrations (10.0, 15.0, 20.0 or 25.0 g kg−1). On day 21, the birds were killed to obtain spleen, cecal tonsil and liver samples to determine the gene expression and antioxidant characteristics. Increasing the Arg concentration linearly decreased (P<0.05) the mRNA expression of splenic interleukin-18 (IL-18) and tumor necrosis factor-α (TNF-α). Dietary Arg supplementation quadratically decreased (P<0.05) the expression of interleukin-1b (IL-1b) and interferon-γ (IFN-γ) mRNA in the spleen. Increasing Arg concentrations linearly and quadratically reduced the expression of IL-18 mRNA in the spleen. Meanwhile, increasing dietary Arg supplementation linearly and quadratically increased the lymphotactin mRNA (P<0.05) expression, and linearly increased the macrophage inflammatory protein-1β (MIP-1β) and toll-like receptor 15 (TLR15) mRNA expression in the cecal tonsils. Dietary Arg supplementation linearly (P<0.05) increased the glutathione peroxidase (GSH-Px), catalase (CAT), and lysozyme (LZM) activities in the liver. However, the malondialdehyde (MDA) activity in the liver was not influenced by the dietary Arg concentration (P>0.05). No significant (P>0.05) effect was found on the activity of superoxide dismutase (SOD) in the liver. Thus high levels of Arg supplementation (>20.0 g kg−1) may potentially suppress the innate immunity of broiler chickens, and dietary Arg supplementation enhances the antioxidant activity in broiler chickens.

L-Arginine Regulates Immune Functions in Chickens Immunized with Intermediate Strain of Infectious Bursal Disease Vaccine

The present study investigated the effects of dietary arginine (Arg) supplementation on immune functions of broiler chickens inoculated with infectious bursal disease vaccine (IBDV). A total of 500 one-day-old female Ross (308) broilers were randomly assigned into 10 treatments (5 replicates per treatment, 10 birds per replicate). On day 14, birds were inoculated intramuscularly with IBDV or saline. Birds were fed diets containing one of five dietary Arg concentrations: 9.9, 13.9, 17.6, 21.3, or 25.3 g/kg respectively. The IBDV inoculation significantly reduced (P<0.05) serum lysozyme and IgA concentration, mitogen-stimulated peripheral blood mononuclear cell (PBMC) proliferation (Con A), PBMC in vitro NO and H2O2 yield, and serum anti-Newcastle disease virus (NDV) body titers. Increasing Arg concentration linearly increased (P<0.05) serum lysozyme concentration, quadratically increased (P<0.05) in vitro PBMC NO yield, linearly and quadratically increased (P<0.05) PBMC proliferation (LPS). Serum anti-IBDV antibody titers tended to be increased quadratically (P＝0.06) by increasing Arg concentration. The Arg requirement of IBDV inoculated chickens (18.9±0.5) for minimum FCR was higher (P<0.05) than that of un-inoculated chickens (16.0±1.3). The Arg requirements of IBDV inoculated chickens for the highest IgA concentration (17.5±0.6 g/kg) and PBMC proliferation (LPS) (19.8±2.1 g/kg) tended to be higher (P<0.10) than those for un-inoculated chickens (IgA: 16.1±0.6 g/kg; PBMC proliferation (LPS): 16.3±0.8 g/kg). These results indicate that dietary Arg supplementation may have a potential effect in alleviating IBDV-inoculation induced immunosuppression via enhancing the immune function of chickens.

L-arginine improves DNA synthesis in LPS-challenged enterocytes.

The neonatal small intestine is susceptible to damage by endotoxin, and this cytotoxicity may involve intracellular generation of reactive oxygen species (ROS), resulting in DNA damage and mitochondrial dysfunction. L-Arginine (Arg) confers a cytoprotective effect on lipopolysaccharide (LPS)-treated enterocytes through activation of the mammalian target of the rapamycin (mTOR) signaling pathway. Arg improves DNA synthesis and mitochondrial bioenergetics, which may also be responsible for beneficial effects of Arg on intestinal mucosal cells. In support of this notion, results of recent studies indicate that elevated Arg concentrations enhances DNA synthesis, cell-cycle progression, and mitochondrial bioenergetics in LPS-treated intestinal epithelial cells through mechanisms involving activation of the PI3K-Akt pathway. These findings provide a biochemical basis for dietary Arg supplementation to improve the regeneration and repair of the small-intestinal mucosa in both animals and humans.

In vitro and in vivo protective effect of arginine against lipopolysaccharide induced inflammatory response in the intestine of juvenile Jian carp (Cyprinus carpio var. Jian)

The present study was designed to assess the possible protective effects of arginine (Arg) against lipopolysaccharide (LPS) induced inflammatory response in juvenile Jian carp (Cyprinus carpio var. Jian) in vivo and in enterocytes in vitro. Firstly, inflammatory response was established by exposing enterocytes to different concentrations of LPS for 24 h. Secondly, the protective effects of Arg against subsequent LPS exposure were studied in enterocytes. Finally, we investigated whether dietary Arg supplementation could attenuate immune challenge induced by LPS in vivo. The result indicated that 10 mg/L LPS could induced inflammatory response in enterocytes. Cells exposed to LPS (10–30 mg/L) alone for 24 h resulted in a significant increase in lactate dehydrogenase release (LDH) (P < 0.05). The cell viability, protein content, alkaline phosphatase activity were decreased by LPS (P < 0.05). Moreover, LPS exposure significantly increased TNF-α, IL-1β, and IL-6 mRNA expression in vitro (P < 0.05). However, pre-treatment with Arg remarkably prevented the increase of TNF-α, IL-1β, and IL-6 by inhibiting the excessive activation of TLR4-Myd88 signaling pathway through down-regulating TLR4, Myd88, NFκB p65, and MAPK p38 mRNA expression (P < 0.05). Interestingly, the experiment in vivo showed that Arg pre-supplementation could attenuate immune challenge induced by LPS via TLR4-Myd88 signaling pathway, and thus protect fish against LPS-induced inflammatory response. In conclusion, all of these results indicated pre-supplementation with Arg decreased LPS induced immune damage and regulated TLR4-Myd88 signaling pathway in juvenile Jian carp in vivo and in enterocytes in vitro.

Supplemental dietary L-arginine attenuates intestinal mucosal disruption during a coccidial vaccine challenge in broiler chickens.

The present study investigated the effects of dietary arginine (Arg) supplementation on intestinal structure and functionality in broiler chickens subjected to coccidial challenge. The present study was a randomised complete block design employing a 3×2 factorial arrangement (n 8) with three dietary concentrations of Arg (11·1, 13·3 and 20·2g/kg) with or without coccidial vaccine challenge (unchallenged and coccidial challenge). On day 14, birds were orally administered with coccidial vaccine or saline. On day 21, birds were killed to obtain jejunal tissue and mucosal samples for histological, gene expression and mucosal immunity measurements. Within 7d of the challenge, there was a decrease in body-weight gain and feed intake, and an increase in the feed:gain ratio (P<0·05). Jejunal inflammation was evidenced by villus damage, crypt dilation and goblet cell depletion. Coccidial challenge increased mucosal secretory IgA concentration and inflammatory gene (iNOS, IL-1β, IL-8 and MyD88) mRNA expression levels (P<0·05), as well as reduced jejunal Mucin-2, IgA and IL-1RI mRNA expression levels (P<0·05). Increasing Arg concentration (1) increased jejunal villus height (P<0·05) and linearly increased jejunal crypt depth (P<0·05); (2) quadratically increased mucosal maltase activity (P<0·05) and linearly decreased mucosal secretory IgG concentration (P<0·05) within the coccidiosis-challenged groups; and (3) linearly decreased jejunal Toll-like receptor 4 (TLR4) mRNA expression level (P<0·05) within the coccidiosis-challenged groups. The mRNA expression of mechanistic target of rapamycin (mTOR) complex 1 pathway genes (mTOR and RPS6KB1) and the anti-apoptosis gene Bcl-2 quadratically responded to increasing dietary Arg supplementation (P<0·05). These results indicate that dietary Arg supplementation attenuates intestinal mucosal disruption in coccidiosis-challenged chickens probably through suppressing TLR4 and activating mTOR complex 1 pathways.