Dietary Arg Levels Research Articles

Effect of dietary arginine levels on growth performance, protein synthesis, antioxidant capacity and immunity of postlarval mud crab Scylla paramamosain

This study investigated the effects of different dietary arginine (Arg) levels on the growth, protein synthesis, antioxidant capacity, and immunity of postlarval mud crab Scylla Paramamosain. Six isonitrogenous and isolipidic diets were formulated to contain 1.51%, 1.81%, 2.16%, 2.35%, 2.73%, and 3.07% dietary Arg levels (dry matter). There were four replicates for each diet treatment (26 crabs per replicate, initial body weight: 7.40 ± 0.15 mg). After eight weeks of feeding trial, the survival and molting frequency (MF) of crabs were not affected by the experimental treatment (P>0.05). Crabs fed the 2.50% Arg diet achieved the highest weight gain (WG) and specific growth rate (SGR) (P<0.05). The whole-body protein content of the 2.16% and 2.73% Arg groups were significantly higher than that of the 1.51% Arg group (P<0.05). Crabs in the 2.35% group obtained the highest levels of phenylalanine and leucine (P<0.05). Superoxide dismutase (SOD), catalase (CAT), and total antioxidant capacity (T-AOC) activity in the 2.16%, 2.35% and 2.73% Arg groups were significantly higher than that in other treatments (P<0.05). Malondialdehyde (MDA) concentration and alkaline phosphatase (AKP) activity were not significantly affected by the treatments. The transcript levels of insulin-like growth factor 1 (igf-1), rapamycinin (TOR), S6 kinase-polypeptide 1 (s6k1) in crabs fed with 2.16% and 2.35% dietary Arg were significantly higher than those in crabs fed with 1.51% and 3.07% dietary Arg (P<0.05). The lowest prophenoloxidase (proPO), relish, and lysozyme transcript levels were observed in crabs fed the 1.51% dietary Arg. The current study founded that the Arg requirement for postlaval S.paramamosain was 2.34% (5.20% of the dietary protein), based on the second order polynomial regression analysis of WG.

Different dietary ratios of arginine, methionine and lysine for turkeys: effects on whole-body composition and nutrient utilization efficiency in the early growth stage

Abstract The growth rate, tissue development and health status of turkeys are affected by the dietary supply of essential amino acids (AAs) such as lysine (Lys), methionine (Met) and arginine (Arg). According to various guidelines, the diets fed to turkeys in the first 4 weeks of the rearing period should contain 1.60–1.76% Lys, 1.60–1.80% Arg and 0.55–0.70% Met. This study investigated the effects of different ratios of Arg and Met in starter diets with 1.60% of Lys content, i.e. a low level, on the whole-body composition of turkeys and nutrient retention efficiency. The experiment lasted for 28 days and it had a two-factorial randomized design with three levels of Arg (90%, 100% and 110%) and two levels of Met (30% or 45%), relative to the content of dietary Lys, with six groups of eight replicates per group and 18 turkeys per replicate. Different dietary Arg and Met levels, relative to Lys, did not affect AA concentrations in the body protein or the proximate whole-body composition (crude protein, crude fat, gross energy and ash) of turkeys. The higher Met level positively influenced energy, protein and Arg utilization and their retention efficiency as well as the growth performance of turkeys. An increase in the dietary level of Arg to 100% and 110% of Lys content had no influence on the growth performance of turkeys and it reduced the retention efficiency of Arg. Differences in the body weight gain, feed intake and Lys utilization of turkeys fed diets with different Arg levels resulted also from the strong interaction between Met and Arg levels. At the lower level of Met in the diet, a decrease in Arg relative to Lys from 100% to 90% resulted in decreased (P = 0.003) feed intake (from 50.34 g to 46.72 g) and growth rate (from 31.84 g to 29.79 g), which was not noted for the higher Met content (45% relative to Lys). At the lowest level of Arg in the diet (90% of Lys content), a decrease in Met relative to Lys from 45% to 30% caused a decrease in Lys retention efficiency (from 61.51% to 56.29%). The results of this study suggest that the higher content of Met in the diet (45% to Lys) and the Arg level corresponding to 90% of Lys content contribute to optimizing nutrient retention efficiency in turkeys during the first 28 days of their life.

The optimal dietary arginine level of laying hens fed with low-protein diets

BackgroundArginine (Arg) is an essential amino acid (EAA) in poultry, an important substrate for protein synthesis and a precursor of several molecules. Supplementation of EAAs with low protein (LP) diet increases the utilization efficiency of dietary crude protein (CP). However, if the EAA requirement is changed in hens fed a LP diet remains to be elucidated. The aim of the present study was to evaluate the optimal level of dietary Arg in the LP diet of hens. A total of 1350 Hy-Line Brown laying hens were randomly allocated to six dietary treatments: a basal diet (16% CP, positive control), or an isoenergetic LP diet (14% CP, 0.80% Arg) supplemented 0, 0.05%, 0.10%, 0.15%, and 0.20% L-Arg, corresponding to 0.80%, 0.85%, 0.90%, 0.95% and 1.00% dietary Arg, respectively.ResultsThe feed efficiency was decreased (P < 0.05) by 0.80% and 1.00% Arg-LP diets, compared to control. Within LP diets, dietary Arg level had significant quadratic effects (P < 0.05) on laying rate, egg mass, and feed efficiency. Compared to control, the plasma CAT activity or T-AOC content were decreased by 0.80% (P < 0.001). However, the hens offered 0.85% and 0.90% Arg-LP diets had higher CAT activity (P < 0.001) than 0.80% Arg-LP diet. In contrast, 1.00% Arg-LP group had the highest MDA and the lowest T-AOC content in plasma, liver, duodenal and jejunal mucosa (P < 0.05). Compared to control, the villus height was decreased by 0.80%, 0.95% and 1.00% Arg-LP diets, while the villus height to crypt depth (V/C) ratio was reduced by 0.95% and 1.00% Arg-LP diets in duodenum.ConclusionThe result demonstrates that LP diet (14% CP) deficient in Arg (0.80% Arg) result in augmented oxidative damage and impaired development of intestinal mucosa. According to the quadratic broken-line regression model, the optimal dietary arginine levels for Hy-Line Brown laying hens fed with low protein diet (14% CP) aged 33 to 40 weeks are 0.85%, 0.86%, and 0.86% to obtained the maximum laying rate, egg mass, and feed efficiency, respectively.

Selected metabolic, epigenetic, nitration and redox parameters in turkeys fed diets with different levels of arginine and methionine

Abstract The amino acid guidelines formulated by British United Turkeys postulate higher levels of lysine (Lys) in turkey diets than those recommended by the National Research Council. However, any modifications in the Lys content of turkey diets should be accompanied by changes in the inclusion rates of other amino acids, including methionine (Met) and arginine (Arg). The research hypothesis postulates that the appropriate inclusion levels and ratios of arginine and methionine in turkey diets with high lysine content can improve the antioxidant status of turkeys without compromising their metabolism. The aim of this study was to determine the influence of different Arg and Met ratios in Lys-rich diets on biochemical indicators, redox status and epigenetic changes in turkeys. The turkeys were assigned to six groups with eight replicates per group and 18 birds per replicate. Six feeding programs, with three dietary Arg levels (90%, 100% and 110%) and two dietary Met levels (30% and 45%) relative to dietary Lys content were compared. During each of the four feeding phases, birds were fed ad libitum isocaloric diets with high Lys content. Our results show that in growing turkeys fed diets with high Lys content, the inclusion rate of Arg can be set at 90% of Lys content with no negative effects on their antioxidant status, metabolism or performance. Diets with high Arg content (110% Lys) are not recommended due to the risk of lipid and protein damage, and an undesirable increase in insulin and T4 levels. Regardless of dietary Arg levels, an increase in the Met inclusion rate from 30% to 45% of Lys content minimizes the oxidation of lipids, proteins and DNA, and increases the antioxidant defense potential of turkeys.

Effects of arginine and/or N-carbamylglutamate supplementation on growth, biochemical composition and expression of growth-regulating factors of hybrid sturgeon (Acipenser schrenckii ♀ ×A. baerii ♂) juveniles fed an arginine-deficient diet

A 2 × 3 factorial experiment was carried out to determine the roles of arginine (Arg) and/or N-carbamylglutamate (NCG) supplemented in diet on growth, biochemical composition as well as mRNA expression levels of growth hormone/insulin-like growth factor-I (GH/IGF-I) in the hybrid sturgeon (Acipenser schrenckii ♀×A. baerii ♂) juveniles raised by the Arg-deficient diet. 30 fish pre tank was fed with each diet (Arg levels: 0% and 1%; NCG levels: 0%, 0.05% and 0.1%) for 8 weeks with three replications for each group. Fish supplemented with 0.1% NCG showed significantly increased final body weight, weight gain rate and protein efficiency ratio, whereas decreased feed conversion ratio compared with those supplemented with 0% NCG (P < 0.05). Dietary Arg or NCG reduced the body moisture but elevated the body crude lipid (P < 0.05). Body crude protein content was significantly increased by the addition of 0.05% NCG (P < 0.05). The Arg concentration of the carcass was significantly affected by dietary Arg and NCG levels (P < 0.05). Dietary NCG supplementation significantly increased the NO concentrations (P < 0.05). The hepatic nitric oxide synthase (NOS) activity in fish supplemented with 0.1% NCG significantly increased relative to that in those supplemented with 0% NCG (P < 0.05). Dietary NCG supplementation markedly increased IGF-I mRNA expression level(P < 0.05). Besides, GH mRNA expression level in 0.1% NCG groups evidently increased relative to those in 0% NCG groups. These results indicated that dietary supplementation with 1% Arg and/or 0.1% NCG could improve growth performance and increase Arg concentration and the GH/IGF-1 gene expression of hybrid sturgeon fed an Arg-deficient diet.

The effect of different dietary ratios of lysine, arginine and methionine on protein nitration and oxidation reactions in turkey tissues and DNA

An assumption was made in the study that the optimal inclusion levels and ratios of lysine (Lys), arginine (Arg) and methionine (Met) in diets with Lys content consistent with National Research Council (NRC) recommendations (1994) contribute to stimulate the antioxidant defense system and prevent disorders resulting from the oxidation and nitration of biologically important molecules. The experiment was carried out on 864 one-day-old Hybrid Converter turkeys divided into six experimental groups (8 replicates per group and 18 birds per replicate) receiving different levels of Arg and Met. Chickens from group Arg90Met30 received 90% Arg and 30% Met relative to Lys; Arg90Met45 – 90% Arg and 45% Met relative to Lys; Arg100Met30 – 100% Arg and 30% Met relative to Lys; Arg100Met45 – 100% Arg and 45% Met relative to Lys; Arg110Met30 – 110% Arg and 30% Met relative to Lys and Arg110Met45 – 110% Arg level and 45% Met level relative to the content of dietary Lys. In comparison with turkeys fed diets with moderate Arg content (100% of Lys content), a decrease in dietary Arg level (90% of Lys content) led to a decrease in plasma 3-nitrotyrosine (3-NT) concentration (163.6 vs. 141.0), whereas an increase in dietary Arg level (110% of Lys content) led to an increase in plasma 3-NT concentration (163.6 vs. 202.6). In comparison with turkeys fed diets with moderate Arg content (100% of Lys content), the lowest dietary Arg level (90% of Lys content) decreased superoxide dismutase (SOD) activity in the intestinal wall (19.68 vs. 17.41) and in the liver (11.51 vs. 7.94), increased SOD activity in the blood (507.6 vs. 961.4) and in breast muscles (6.26 vs. 7.43) and increased the concentration of malondiadehyde in breast muscles (1.10 vs. 1.50). An increase in dietary Met content from 30 to 45% of Lys content caused a decrease in plasma protein carbonyl concentration (4.33 vs. 3.8) and catalase activity in breast muscles (54.70 vs. 49.66), and an increase in SOD activity in the liver (8.90 vs. 10.41). The highest dietary Arg level (110% of Lys content) did not induce the oxidation of lipids, proteins or DNA, but it increased the risk of protein nitration. The lowest dietary Arg level (90% of Lys content) deteriorated the antioxidant status of turkeys. Regardless of dietary Arg levels, an increase in Met content from 30 to 45% of Lys content stimulated the antioxidant defense system of turkeys.

PSVIII-7 Dietary L-arginine supplementation enhances growth performance, intestinal antioxidant capacity, immunity and modulate gut microbiota in yellow feathered chickens

Abstract This study investigated the effects of dietary Arginine (Arg) on performance, intestinal antioxidant capacity, immunity, and gut microbiota in Chinese yellow-feathered chickens. One thousand and two hundred 1-day-old female Qingyuan partridge chickens were randomly assigned to 5 groups with 6 replicates of 40 birds each. Chickens were fed diets with 5 total Arg levels (8.5, 9.7, 10.9, 12.1 and 13.3 g/kg) without antibiotics for 30 D. Average daily feed intake, average daily gain, and feed conversion ratio were improved with dietary Arg levels (P &amp;lt; 0.05). Dietary Arg level had a linear (P &amp;lt; 0.05) or quadratic (P &amp;lt; 0.05) effect on the gene expression of glutathione peroxidase 1, hame oxygenase 1, nuclear factor erythroid 2, linearly and quadraticly increased activities of GSH-Px and total antioxidant capacity in the jejunum and ileum. In addition, relative expression of interleukin-1β and toll-like receptor 4 decreased linearly (P &amp;lt; 0.05) and quadratically (P &amp;lt; 0.05) in the ileum with increasing dietary Arg levels; secretory immunoglobulin A contents were increased. In addition, sequencing data of 16S rRNA indicated that dietary Arg increased the abundances of Firmicutes phylum, Romboutsia and Candidatus Arthromitus genus, while decreased that of Clostridium sensu stricto 1. A diet containing 12.1 g Arg/kg could promote growth performance, intestinal antioxidation, innate immunity and modulate gut microbiota in yellow feathered chickens.

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 L-arginine supplementation enhances growth performance, intestinal antioxidative capacity, immunity and modulates gut microbiota in yellow-feathered chickens

This study investigated the effects of dietary Arginine (Arg) on performance, intestinal antioxidative capacity, immunity, and gut microbiota in Chinese yellow-feathered chickens. One thousand two hundred 1-day-old female Qingyuan partridge chickens were randomly assigned to 5 groups with 6 replicates of 40 birds each. Chickens were fed diets with 5 levels of total Arg (8.5, 9.7, 10.9, 12.1, and 13.3 g/kg) without antibiotics for 30 d. The ADFI, ADG, and feed conversion ratio were improved with dietary Arg levels (P < 0.05). The proportions of CD3+ and CD4+/CD8+ lymphocytes responded in a linear (P < 0.05) manner and those of CD4+ in a linear or quadratic (P < 0.05) manner as dietary Arg levels increased. Dietary Arg level had a linear (P < 0.05) or quadratic (P < 0.05) effect on the gene expression of glutathione peroxidase 1, heme oxygenase 1, nuclear factor erythroid 2–related factor 2, and the activities of glutathione peroxidase and total antioxidative capacity in the jejunum and ileum. The relative expression of IL-1β, myeloid differentiation primary response 88, and Toll-like receptor 4 decreased linearly (P < 0.05) in the ileum with increasing dietary Arg levels; secretory IgA contents were increased. In addition, sequencing data of 16S rRNA indicated that dietary Arg increased the relative abundance of Firmicutes phylum, Romboutsia and Candidatus Arthromitus genera, while decreased that of Clostridium sensu stricto 1. A diet containing 12.1 g Arg/kg promoted growth performance, intestinal antioxidation, and innate immunity and modulated gut microbiota in yellow-feathered chickens.

Effect of dietary l-arginine of broiler breeder hens on embryonic development, apparent metabolism, and immunity of offspring

This study investigated the effects of supplemented l-arginine (l-Arg) in broiler breeder hens' diets on the embryonic development and physiological changes of offspring during the hatching period. A total of 480 35-wk-old healthy female Arbor Acres broiler breeders were randomly divided into 6 groups and fed a corn and soybean meal diet with 6 digestible Arg levels (0.96%, 1.16%, 1.35%, 1.55%, 1.74%, and 1.93%). After a 10-wk experiment, eggs were collected for incubation. At embryonic day (E) 11 to E21, eggs, embryos, and organs (liver, breast muscle, and thigh muscle) were weighed. Total protein, urea nitrogen, creatinine, cholesterol, and triglyceride in plasma, were measured. Plasma level of immunoglobulin G (IgG), immunoglobulin M (IgM), and nitric oxide synthase (NOS) were measured at E13, E17, and E21. Messenger RNA expression of carbamoyl phosphate synthase I (CPS1), ornithine transcarbamylase (OTC), and argininosuccinate synthase (ASS) in liver and breast muscle tissues was assessed at E13, E17, and E21. The results showed that 1.16% Arg in maternal diet increased egg weight (P < 0.05). The level of Arg in maternal diet has a significant effect on organ index and embryo weight of multiple embryonic days (P < 0.05). Embryonic plasma total protein concentration was significantly affected by maternal dietary Arg level (P < 0.05) and exhibited quadratic responses at E11, E15, E17, and E21 (P < 0.01). Plasma urea nitrogen, creatinine, triglyceride, and cholesterol level were also significantly affected by the level of maternal Arg at different embryonic ages (P < 0.05). Dietary digestible Arg levels quadratically influenced plasma urea nitrogen level at E21 (P < 0.05) and cholesterol concentration at E17 and E19 (P < 0.01). L-Arg supplementation in maternal diet significantly improved the IgG level at E17 and E21 (1.16%, 1.35%, 1.55%, and 1.74%; P < 0.05), the IgM level at E13 (1.35%, 1.55%, 1.74%, and 1.93%) and E17 (P < 0.05) and the NOS level at E13, E17, and E21 (P < 0.05). Maternal dietary L-Arg supplementation significantly improved the expression of CPS1 gene, OTC gene (1.16%, 1.35%, and 1.55%), and ASS gene (1.35% and 1.55%) in the liver (P < 0.05), and also enhanced the CPS1 gene (except 1.35%) and OTC gene (1.55% and 1.74%) expression in the breast muscle (P < 0.05). In conclusion, maternal Arg level affected the embryonic development of offspring and regulated the apparent metabolic programming and immunity state of the embryo. Arginine level of 1.55% in hens' diet was beneficial to the protein synthesis and immunity of the offspring in the embryonic period, and it was recommended to obtain healthy offspring.

Effects of different levels of arginine and methionine in a high-lysine diet on the immune status, performance, and carcass traits of turkeys

We postulated that the use of appropriate levels and proportions of arginine (Arg) and methionine (Met) in compound feed with high lysine content (Lys) would make it possible to fully exploit the growth potential of modern fattening turkey crossbreds, without compromising their immune system. The aim of this study was to determine the effect of different ratios of Arg and Met in diets with high Lys content on the performance and immune status of turkeys. The turkeys were assigned to 6 groups with 8 replicates per group and 18 birds per replicate. Six feeding programs, with 3 dietary Arg levels (90, 100, and 110%) and 2 dietary Met levels (30 and 45%) relative to dietary Lys content, were compared. During each of 4 feeding phases (weeks 0–4, 5–8, 9–12, and 13–16), birds were fed ad libitum isocaloric diets containing high level of Lys, approximately 1.83, 1.67, 1.49, and 1.20%, respectively. The dietary treatments had no effect on daily feed intake or body weight at any stage of the study. The protein content of the breast meat was higher in the treatments with the highest Arg level (110%) compared with the lowest Arg level (90%). Similarly, protein content was higher in the treatments with the higher Met level compared with the lower Met level. Higher plasma levels of tumor necrosis factor, interleukin 6 (IL-6), and immunoglobulin Y were found in turkeys fed diets with the lowest Arg content. An increase in Met content resulted in a decrease in plasma content of IL-6. In growing turkeys fed diets high in Lys, an Arg level of 90% relative to Lys can be used without negatively affecting production results and immune system. Regardless of dietary Arg levels, an increase in Met content does not stimulate the immune defense system and shows no effect on growth performance of turkeys in current trial.

The effect of different dietary ratios of arginine, methionine, and lysine on the performance, carcass traits, and immune status of turkeys

The research hypothesis postulated that the optimal dietary inclusion levels and ratios of lysine (Lys), arginine (Arg), and methionine (Met) can increase the growth potential of hybrid turkeys and limit metabolic disorders that weaken immune function. The experiment was carried out in a full rearing cycle, from 1 to 16 wk of age, in a two-factorial randomized design with 3 levels of Arg and 2 levels of Met (90, 100 and 110% of Arg, and 30 or 45% of Met, relative to the content of dietary Lys), with 6 groups of 8 replicates per group and 18 turkeys per replicate. In the first and second month of rearing, a significant dietary Arg-by-Met interaction was noted for daily feed intake and body weight gain, and a more beneficial effect was exerted by higher Met content and medium Arg content. Throughout the experiment, the higher dietary Met level increased the final body weight (BW) of turkeys (P = 0.001). Different dietary Arg levels had no influence on the growth performance of turkeys, but the lowest level decreased dressing yield (P = 0.001), and the highest level increased the percentage of breast muscles in the final BW of turkeys (P = 0.003). The lowest Arg level (90% of Lys content) undesirably increased the concentration of the proinflammatory cytokine IL-6 (P = 0.028) and decreased globulin concentration (P = 0.001) in the blood plasma of turkeys. The higher dietary Met level (45% of Lys content) increased plasma albumin concentration (P = 0.016). It can be concluded that higher dietary levels of Met (45 vs. 30% of Lys content) and Arg (100 and 110 vs. 90% of Lys content) have a more beneficial effect on the growth performance and immune status of turkeys.

The optimal arginine requirement in diets for juvenile humpback grouper, Cromileptes altivelis

An 8-week feeding trial was conducted to evaluate the effects of dietary arginine (Arg) levels on growth performance, gut micromorphology, oxidation resistance and immune responses of humpback grouper, Cromileptes altivelis. Seven isoenergetic (340 kcal per 100 g of dry matter), isoproteic (50% of dry matter) and isolipidic (10% of dry matter) experimental diets were formulated to contain 1.74%, 2.42%, 3.14%, 3.58%, 4.06%, 4.54% and 5.21% dietary Arg levels. Triplicate groups of 12 fish (average initial body weight: 6.55 ± 0.1 g) were fed to apparent satiation by hand twice daily (08:00 h and 16:00 h) in an indoor recirculating seawater system which was consisted of 21 glass tanks (length 60 cm × width 45 cm × height 50 cm) and mechanical and biological water filters. After the feeding trial, all remaining fish were challenged by 2.5 mg Cu(II)·L−1, and survival rates were recorded for 12 h. Results showed that weight gain% (WG%), protein efficiency ratio (PER) as well as protein productive value (PPV) of fish were improved with the increments in dietary Arg from 1.74% to 3.58%, and thereafter, values of these parameters displayed a declining trend as dietary Arg level continued to rise from 3.58% to 5.21%. Fish fed 3.14% and 3.58% dietary Arg had lower FCR and daily feed intake (DFI) than fish fed other dietary Arg levels. Quadratic regression analysis of WG% against dietary Arg levels indicated that optimal dietary Arg level for maximum growth of humpback grouper was 3.39% of dry matter (6.78% of dietary protein). Hepatosomatic index (HSI) was reduced as dietary Arg level increased. Fish fed 3.58% dietary Arg had higher whole-body protein content than fish fed other dietary Arg levels. Expression of hepatic insulin-like growth factor-I (IGF-1), target of rapamycin (TOR), S6 kinase1 (S6K1) and hypothalamus growth hormone receptor (GHR) in fish fed 3.14% and 3.58% dietary Arg was higher than that in fish fed other dietary Arg levels. Gut micromorphology was significantly influenced by dietary Arg levels. After the exposure to 2.5 mg Cu(II)·L−1 water for 12 h, fish fed 3.14% and 3.58% dietary Arg had higher survival ratios and expression of NF-E2-related factor 2 (Nrf2) and heat shock proteins genes 70 (HSP70) in head kiney. In serum, fish fed 3.58% dietary Arg had higher superoxide dismutase (SOD) and catalase (CAT) activities and immunoglobulinM (IgM) concentrations than fish fed other dietary Arg levels. In conclusion, the optimal dietary Arg requirement for maximal growth of humpback grouper was estimated to be 3.39% of dry matter (6.78% of dietary protein), and suitable dietary Arg supplementations improved growth performance, gut micromorphology, oxidation resistance as well as immunity of this species.

Dietary arginine affects growth, gut morphology, oxidation resistance and immunity of hybrid grouper (Epinephelus fuscoguttatus♀×Epinephelus lanceolatus♂) juveniles.

An 8-week growth trial was conducted to evaluate the effects of dietary arginine (Arg) levels on growth, gut morphology, oxidation resistance and immunity of hybrid grouper (Epinephelus fuscoguttatus♀×Epinephelus lanceolatus♂) juveniles. Seven isoenergetic (1465 kJ (350 kcal)/100-g DM), isoproteic (53·5 % of DM) and isolipidic (7 % of DM) experimental diets were formulated to contain graded Arg levels ranging from 1·9 to 4·7 % (dry weight) at approximately 0·5 % increments. Each diet was randomly assigned to triplicate groups of 16 juvenile fish (average initial body weight: 11·7 (sd 0·1) g) and was administered twice daily (08.00 and 16.00 hours). After the growth trial, all remaining fish were fed their prescribed diets for 2 d and then exposed to 4·5 mg Cu2+/l water for 36 h. Results showed that growth performance and feed utilisation of experimental fish were significantly affected by different dietary Arg levels. Weight gain % (WG%) of fish was increased as dietary Arg increased, reaching a peak value at 3·8 % dietary Arg level, and when dietary Arg level increased to 4·7 % WG% was reduced. Fish fed 1·9 and 2·2 % dietary Arg levels had higher daily feed intake compared with fish fed other dietary Arg levels. Feed conversion ratios in fish fed 1·9, 2·2, 2·7 and 4·7 % dietary Arg levels were higher than those in fish fed 3·1, 3·8 and 4·1 % dietary Arg levels. Protein efficiency ratio and protein productive value (PPV) increased with an increase in dietary Arg, up to a peak value at 3·8 % dietary Arg level, above which these parameters declined. On the basis of quadratic regression analysis of weight gain % (WG%) or PPV against dietary Arg levels, the optimal dietary Arg requirement for hybrid grouper was estimated to be 3·65 %. Fish fed 3·8 % dietary Arg had higher whole-body and muscle protein contents compared with fish fed other dietary Arg levels. Fish fed 3·8 and 4·1 % dietary Arg levels had higher levels of mRNA for insulin-like growth factor-I and target of rapamycin in the liver compared with fish fed other dietary Arg levels. Hepatic S6 kinase 1 mRNA expression in fish fed 3·8 % dietary Arg level was higher than that in fish fed any of the other dietary Arg levels. Gut morphology, hepatic antioxidant indices and immune indices in serum and head kidney were significantly influenced by dietary Arg levels. In conclusion, the optimal dietary Arg requirement for hybrid grouper was estimated to be 3·65 %, and suitable dietary Arg supplementations improved gut morphology and oxidation resistance of hybrid grouper.

Metabolic and immune effects of orange-spotted grouper, Epinephelus coioides induced by dietary arginine

Arginine (Arg) as an important substrate for protein metabolism and endocrine influences on fish health directly. To evaluate the effect of dietary Arg on these endocrine and immunity of juvenile orange-spotted grouper (Epinephelus coioides), an experiment adding Arg with 0.00, 0.30, 0.60, 0.90, 1.20, 1.50, and 1.80% in seven diets was conducted. Dietary Arg levels reached 2.13 (Diet 1), 2.42 (Diet 2), 2.71 (Diet 3), 2.95 (Diet 4), 3.20 (Diet 5), 3.48 (Diet 6) and 3.74% (Diet 7), respectively. Each treatment was randomly assigned to triplicate groups of 30 fish (7.52 ± 0.02 g) each tank. The present results indicated that different Arg levels of diets were no significant effects on the fish survival rate of each groups (P > 0.05) after 8 weeks feeding experiment. The highest weight gain and specific growth rate were found in Diet 4, and significantly higher than the other groups (P < 0.05). Hepatic arginase activities were significantly higher in fish fed Diet 6 and Diet 7 compared to the activities of the fish fed first three Diets (P < 0.05). Hepatic ornithine decarboxylase activities of fish fed Diet 1 and Diet 2 were significantly decreased compared to the fish fed Diet 4–Diet 7 (P < 0.05). With ascending dietary Arg, the serum Insulin (INS) and insulin-like growth factor I (IGF-I) levels significantly increased. Gene expression of tissue toll-like receptors 22 in the three tissues were found first up-regulated and then down-regulated with the Arg increasing. Gene expression of major histocompatibility complex II in liver and kidney significantly increased in fish fed Diet 4 and Diet 6, and decreased thereafter. However, gene expression of hepcidin decreased with dietary Arg increased. The present study showed alterations in serum INS and IGF-I levels in response to Arg-induced growth activation. Additionally, the results indicate that Arg has beneficial effects on regulating mRNA expression of immune-associated genes and improving humoral and cellular immunity of fish.

Marginal deficiencies of dietary arginine and methionine could suppress growth performance and immunological responses in broiler chickens.

The present study was conducted to investigate the effects of different levels of dietary arginine (Arg) and methionine (Met) on performance, immune responses, and carcass characteristics of broiler chickens. A total of 540day-old Ross 308 broiler chicks were randomly assigned into the nine experimental diets, consisting five replicates of 12 birds each. Dietary treatments included three different levels (90%, 100%, and 110% of National Research Council [NRC] specifications) of either dietary Arg or Met, which were fed to the birds according to a 3×3 factorial arrangement of treatments during a 42days feeding trial. Results showed that supplementation of Arg and Met into the deficient-diets increased (p<.01) weight gains during all trial periods. Although average daily feed intake (ADFI) was not influenced by dietary treatments, increasing Arg up to 100% of NRC recommendations improved (p<.05) feed conversion ratio (FCR) throughout the trial period. Similarly, supplementation of deficient-diets with Met improved FCR values. There was a significant (p<.01) Arg×Met interaction for ADFI during the starter period; increasing the dietary Arg level increased ADFI when the diets were deficient in Met, while had an opposite effect in diets containing higher dietary Met levels. On the other hand, dietary Met fortification improved (p=.067) FCR values to a greater extent in 110% Arg-diets during the entire trial period. Although different levels of Arg and Met had no marked effects on carcass yield and abdominal fat percentage, supplemental Arg up to 100% of NRC values increased (p<.01) the relative weights of spleen and bursa of Fabricius. Furthermore, bursa weight was affected by Arg×Met interaction (p<.01), so that supplemental Arg level of 100% of NRC increased the relative bursa weight in birds that were fed diets containing 90% and 110% of Met. Serum uric acid level was decreased (p<.05) as a result of dietary Arg fortification up to 110% of NRC recommended values. Supplementation of deficient-diets with Met decreased (p<.05) serum cholesterol level. Although Newcastle antibody titer was not affected by dietary Arg or Met levels, Arg fortification of deficient-diets increased (p<.001) antibody responses against infectious bronchitis (IBV) and bursal (IBD) disease viruses. Similarly, Met supplementation of deficient-diets increased IBD antibody titer. There were significant (p<.05) Arg×Met interactions for IBV and IBD titers; Met fortification of 110% Arg-diets was more effective in increasing antibody titers. An increase in dietary Met level up to 100% of NRC values increased (p<.001) serum concentration of γ-globulins. The present findings imply that supplemental Arg could affect feed efficiency and antibody responses when the diets were already fortified with a sufficient Met level.

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.

Effects of dietary arginine and glutamine on growth performance, nonspecific immunity, and disease resistance in relation to arginine catabolism in juvenile turbot (Scophthalmus maximus L.)

A 12-week feeding trial was conducted to investigate the effects of dietary arginine (Arg), glutamine (Gln), and their interactions on growth performance, nonspecific immunity, disease resistance, and Arg catabolism in juvenile turbot (Scophthalmus maximus L.). The basal diet was formulated with white fish meal, soybean meal, and corn gluten meal to contain 50% crude protein and 12% crude lipid. Nine isoproteic and isolipidic experimental diets were formulated by supplementing the basal diet with three levels of l-Arg and l-Gln (0.0%, 1.0%, and 2.0% each). Triplicate groups of 35 fish were fed a fixed ration twice daily in an indoor recirculating seawater system. After the feeding trial, fish were challenged by Edwardsiella tarda and survival rate (SR) was recorded for 7days. The results showed that dietary Arg and Gln levels did not significantly affect growth performance of juvenile turbot (P>0.05). Respiratory burst activity in head-kidney macrophages increased significantly as dietary Arg or Gln increased (P<0.05), but no significant interactions was observed (P>0.05). Significant interactions between dietary Arg and Gln were observed on lysozyme and glutathione peroxidase activity in serum (P<0.05). There was also a significant interactive effect of dietary Arg and Gln on inducible nitric oxide synthase activity in serum and liver, and arginase I gene expression in liver (P<0.05). Fish fed diets with the highest Arg and Gln showed significantly higher levels of arginase I gene expression in liver (P<0.05). After the E. tarda challenge, SR of juvenile turbot were significantly improved as dietary Arg increased (P<0.05), but no significant effect of dietary Gln and their interactions was observed (P>0.05). It can be concluded that inclusion of Arg and Gln in the diet did not have a positive effect on growth performance of juvenile turbot, but significantly improved nonspecific immune responses. Dietary Arg and Gln levels also had significantly interactive effects on Arg catabolism. Disease resistance was significantly enhanced with the increasing of dietary Arg.

Effects of dietary arginine levels and carbohydrate-to-lipid ratios on mRNA expression of growth-related hormones in largemouth bass, Micropterus salmoides

Utilizing the tissue samples and growth data collected from our two preceding researches in largemouth bass (LMB), we have investigated effects of dietary arginine (Arg) levels and carbohydrate-to-lipid (CHO/LIP) ratios on the GH, IGF-I and insulin expression in related tissues to find possible relationships between the nutrient intake, growth performance and transcript level. Hepatic IGF-I and pituitary GH mRNA levels were significantly up-regulated by lower dietary Arg levels from 1.94% to 3.01% and by higher levels from 2.76% to 3.01%, respectively, while Brockmann body (BB)-containing tissue insulin mRNA expression was not affected. Dietary CHO/LIP ratios ranging from 0.32 to 5.17 (w/w) affected pituitary GH, liver IGF-I and BB-containing tissue insulin mRNA expression in a ratio-specific pattern. The lower ratios from 0.32 to 2.36 significantly up-regulated GH and insulin transcript levels, but significantly down-regulated IGF-I transcript levels; the higher ratios did no longer exert any further effects on them. Meanwhile, two strong positive correlations (r=0.892, r=0.885) between hepatic IGF-I transcript levels and specific growth rates of tested fish were observed with varying dietary Arg levels and CHO/LIP ratios, respectively. These findings indicate that in LMB dietary Arg levels and CHO/LIP ratios regulate differentially the endocrine system of GH, IGF-I and insulin at transcription level; this system, in turn, plays a fundamental role in the regulation of the nutrient metabolism and somatic growth; and that hepatic IGF-I mRNA abundance should be a more reliable index to assess growth and nutritional fitness than the others, at least in LMB.

Dietary arginine levels alter markers of arginine utilization in peripheral blood mononuclear cells and thymocytes in young broiler chicks1

Arginine is an essential amino acid in Aves and is also an important substrate for the immune system. Dietary Arg in avian diets must be sufficient to not only support growth but also immunity. To better understand Arg needs for immunity, 2 experiments examined markers of Arg use by the immune system in growing broiler chicks. Broiler hatchlings were fed diets containing adequate (1.2%) or high (1.35%) dietary Arg for 21 d. On d 7, the Arg importer cationic amino acid transporter-1 mRNA abundance in peripheral blood mononuclear cells was 2-fold greater in chicks fed 1.35% Arg than in chicks fed 1.2% Arg (P < 0.05). On d 14, chicks fed the diet containing 1.2% Arg had 2.5-fold greater mRNA abundance of the y(+)L type amino acid transporter-2 exporter compared with chicks fed 1.35% Arg (P < 0.05). In experiment 2, broiler hatchlings were fed diets containing low (1.1%), high (1.3%), or excess (1.5%) dietary Arg for 17 d. The percentage of peripheral blood B cells at a given age tended (P = 0.06) to be affected by the dietary Arg level. On d 14, but not on d 10 or 17, the percentage of monocytes from chicks fed 1.5% Arg was higher than from those fed 1.1 and 1.3% Arg (P < 0.05). These studies indicate that the dietary Arg levels in excess of 1.2% increase the mRNA abundance of markers for Arg use by immune cells undergoing development (thymocytes) and at maintenance (peripheral blood mononuclear cells) and also increase the percentage of monocytes within peripheral blood. Understanding Arg use by the immune system will provide a better understanding of how to formulate immunosupportive diets to promote animal health.