Arginine Requirement Research Articles

PSLBI-16 Arginine requirements of young adult and senior Labrador retrievers

PSLBI-16 Arginine requirements of young adult and senior Labrador retrievers

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).

Beyond protein synthesis: the emerging role of arginine in poultry nutrition and host-microbe interactions.

Arginine is a functional amino acid essential for various physiological processes in poultry. The dietary essentiality of arginine in poultry stems from the absence of the enzyme carbamoyl phosphate synthase-I. The specific requirement for arginine in poultry varies based on several factors, such as age, dietary factors, and physiological status. Additionally, arginine absorption and utilization are also influenced by the presence of antagonists. However, dietary interventions can mitigate the effect of these factors affecting arginine utilization. In poultry, arginine is utilized by four enzymes, namely, inducible nitric oxide synthase arginase, arginine decarboxylase and arginine: glycine amidinotransferase (AGAT). The intermediates and products of arginine metabolism by these enzymes mediate the different physiological functions of arginine in poultry. The most studied function of arginine in humans, as well as poultry, is its role in immune response. Arginine exerts immunomodulatory functions primarily through the metabolites nitric oxide (NO), ornithine, citrulline, and polyamines, which take part in inflammation or the resolution of inflammation. These properties of arginine and arginine metabolites potentiate its use as a nutraceutical to prevent the incidence of enteric diseases in poultry. Furthermore, arginine is utilized by the poultry gut microbiota, the metabolites of which might have important implications for gut microbial composition, immune regulation, metabolism, and overall host health. This comprehensive review provides insights into the multifaceted roles of arginine and arginine metabolites in poultry nutrition and wellbeing, with particular emphasis on the potential of arginine in immune regulation and microbial homeostasis in poultry.

Dietary arginine levels affect growth performance, intestinal antioxidant capacity and immune responses in largemouth bass (Micropterus salmoides)

This study explored the role of dietary arginine level (DAL) on growth, intestinal antioxidant status and immune response in juvenile largemouth bass (Micropterus salmoides), providing guidance for the optimization of commercial feed in largemouth bass. Six graded arginine levels in diets were fed to the fish for 8 weeks (1.96%, 2.28%, 2.52%, 2.81%, 3.09% and 3.35% diets). The findings were as follows: with increasing DALs, FW, WG and SGR increased first and decreased, and FCR showed the opposite trend. There was no difference in the contents of crude protein and ash among graded DAL (P > 0.05). DAL (3.09% and 3.35%) significantly increased the activities of plasma AST (P < 0.05). Certain range of dietary arginine levels could improve antioxidant ability by regulating intestinal antioxidant-related parameters including the activities of SOD, GPx, and the contents of GSH and MDA. The gene expression of Nrf2 was significantly increased in response to 2.52% DAL, while Keap1 expression was decreased (P < 0.05). Furthermore, 1.96% and 2.28% DALs significantly increased the gene expression of CAT and GPx (P < 0.05), and SOD expression was the highest in response to 2.52% and 2.81% DALs (P < 0.05). Compared with the control group, the relative expressions of IL-1β, IL-8, TNF-α and NF-κB were reduced that were fed 2.52%− 3.35% DALs. Moreover, the relative expression of IL-10 and TGF-β were peaked in response to 2.81% DAL (P < 0.05). The quadratic regression curve analysis according to the growth results of SGR and FCR, the expressions of IL-10 and TGF-β showed that the optimal dietary arginine requirement for largemouth bass were 2.40%− 2.63% (5.03%−5.46% of dietary protein), and could promote growth, intestinal antioxidant capacity and immune responses in juvenile largemouth bass.

Dietary arginine requirements of oriental river prawns (Macrobrachium nipponense) assessed using growth and biomarkers of antioxidant capacity

An 8-week feeding trial was carried out to determine the dietary arginine requirement of oriental river prawns (Macrobrachium nipponense). Prawns of initial tank biomass (10.0 g) were fed isonitrogenic (ca 38% protein) and isolipidic diets (ca 7.5% lipid) with incremental concentrations of arginine (0.75, 1.19, 1.61, 2.02, 2.46, and 2.81%). The prawns were randomly assigned into 24 cylindrical polypropylene tanks (1000L), with 50 prawns in each tank replicated four times in a completely randomized design, and were fed three times daily to apparent satiation. Muscle samples were used to analyze the amino acid profiles. Hepatopancreas were collected for antioxidant activity and immune-related gene expression. The results indicated that the survival, growth performance and feed utilization were significant higher (p < 0.05) in prawns fed with 2.02% dietary arginine than in other treatments except the treatment with 2.46% dietary arginine. The highest biomass increase (25.5 ± 0.5 g), protein efficiency ratio (1.05 ± 0.08) and survival (87.0 ± 2.7%) were found in prawns fed with dietary 2.02%, and the lowest feed conversion ratio (2.53 ± 0.18) was observed in the same group. Whole-body crude protein content (15.4 ± 0.1%), lipid content (2.5 ± 0.1%) and muscle arginine content (1.47 ± 0.03%) significantly increased in prawn fed with dietary 2.02% arginine compared with other groups except dietary 2.46% arginine (p < 0.05). With increased dietary arginine supplementation up to 2.02%, the activities of hepatopancreas superoxide dismutase (25.07 ± 0.64 U/mg prot) and glutathione peroxidase (461.89 ± 8.79 U/mg prot) were increased (p < 0.05); nevertheless, the glutathione content (23.45 ± 3.47 μmol /mg prot) in the 2.02% dietary arginine group was similar with that of the control group (p > 0.05). Moreover, the hepatopancreas gene expressions of Toll-like receptor, dorsal, immune deficiency, and relish were significantly upregulated in the prawn fed with1.61% dietary arginine (p < 0.05). Broken-line, quadratic and cubic regression models are used to evaluate the optimal arginine requirements. The broken-line regression of biomass increase, based on the highest R2 value, showed that the optimum arginine requirement of oriental river prawns was 2.12% of dry matter (5.61% dietary protein). The optimum dietary arginine requirement, according to the cubic regression analysis for superoxide dismutase activity, was 2.27% of dry matter (6.01% of dietary protein). The ideal arginine concentration for antioxidant enzymes activity was thought to be higher than that for growth.

Arginine Uptake by Chick Kidney Mitochondria

Arginine uptake by kidney mitochondria in two strains of chicks of high (HA) and low (LA) requirement of dietary arginine was studied by using an ion-exchange method. Dietary factors influencing uptake of arginine were also investigated. The results indicate that arginine uptake by kidney mitochondria of HA chicks was significantly higher than the LA chicks when arginine-deficient diet or diet with excess lysine was fed. The arginine uptake by kidney mitochondria reflects the kidney arginase activity. Both arginase activity and arginine uptake inversely correlated with growth rate of the two strains of chicks. However, the dietary factors that affect kidney mitochondria arginase activity are not completely parallel to the uptake of arginine by kidney mitochondria. A system that facilitates entry of arginine into kidney mitochondrial membrane is suggested.arginine uptake lysine uptake kidney mitochondria

Effects of Dietary Arginine Level on Growth Performance and Immune Response in Monopterus albus

To assess the dietary arginine requirement of Monopterus albus (21 ± 0.03 g), we compared six diets containing different arginine levels (2.03%, 2.58%, 3.16%, 3.63%, 4.24%, and 4.88%). The results revealed that dietary arginine content had a significant effect on weight gain (WG), specific growth rate (SGR), IL-1β, IL-10, lysozyme, and complement C3 activity in Monopterus albus ( p &lt; 0.05 ). The WG and SGR increased with increasing dietary arginine levels, and the regression analysis found that the optimum dietary arginine level for growth of rice field eel was 4.28–4.35% of the dry diet. However, the C3 and LZM activities peaked in the 2.58% arginine diet group ( p &lt; 0.05 ). The dietary arginine level had no significant effect on the viscerosomatic index, hepatosomatic index, condition factor, survival rate, nitric oxide, total nitric oxide synthase, insulin, growth hormone, trypsin, lipase, or amylase activities ( p &gt; 0.05 ). Arginine can significantly promote Monopterus albus growth; however, the immunity of Monopterus albus decreases as the arginine level exceeds 2.58%. A comprehensive assessment of growth and immunity recommends the optimum arginine level for Monopterus albus was 3.16–3.63% of the dry diet, corresponding to 6.58–7.70% of the dietary protein.

Modeling the response of Japanese quail to arginine intake.

Understanding how Japanese quails respond to arginine intake has been an objective that previous studies have not fulfilled. The main responses to be quantified include the arginine requirement for maintenance (mg/kg0.67) and egg mass production (mg/g). Quantifying maintenance and production relationships are essential steps for predicting animal response. The current study aimed to describe how quails respond to arginine intake and determine arginine requirements for maintenance and egg production in Japanese quails. The experiment was carried out in a completely randomized design, with seven treatments and seven replicates with individual birds as experimental units. The arginine levels were: 2.43, 3.64, 4.85, 6.07, 9.07, 12.13, and 14.56 g/kg. The experiment lasted for eight weeks. The variables analyzed were daily arginine intake, daily arginine deposition in eggs, and body weight. The data were analyzed using a mixed model, with the experimental unit being the random effect and the experimental levels of arginine as a fixed effect. When the effect of arginine levels was detected (P≤0.05), saturation kinetics and an exponential model with four parameters (monomolecular) were adopted. ANOVA results indicated that dietary arginine levels significantly affected (P<0.01) the analyzed variables. The formulation strategy of the experimental diets allowed amplitude in the dietary arginine levels, and according to bird responses, arginine was the limiting nutrient. The arginine requirement for body weight maintenance (BW0.67) was estimated to be 90 mg/kg BW0.67 by the monomolecular function. The requirement for egg mass (EM) production was estimated to be 25 mg/g per egg. A factorial model was parameterized as follows: daily arginine intake mg/bird = 90 × BW0.67 + 25 × EM ± 12 mg. The model was applied to data obtained from literature, and the resultant error was within the expected limit of 12 mg. The recommended daily arginine intake for the daily production of 11 g of egg and 180 g of BW was determined to be 304 mg/bird. The current study provides procedures that researchers can easily adopt.

Dietary Arginine Modulates Growth Performance, Hemato-Biochemical Indices, Intestinal Enzymes, Antioxidant Ability and Gene Expression of TOR and 4E-BP1 in Rainbow Trout, Oncorhynchus mykiss Fingerlings

We evaluated the effect of arginine on growth, hemato-biochemical variables, intestinal enzymes, antioxidant ability, and expression of target of rapamycin (TOR) signaling pathway related genes in fingerling Oncorhynchus mykiss. A series of six uniform diets consisting of 450 g kg-1 of protein and 20.9 g-1 of energy with graduated levels (10.0, 12.5, 15.0, 17.5, 20.0, and 22.5 g kg-1) of arginine were formulated. Significant (p &amp;lt; 0.05) variations were observed in various analyzed parameters. Growth parameters showed a positive linear trend with increasing arginine levels up to 17.5 g kg-1. Fish offered 17.5 g kg-1 of dietary arginine exhibited highest body protein, lowest moisture, and intermediate fat contents, whereas, body ash content did not significantly (p &amp;gt; 0.05) change with respect to each dietary arginine offered diet, except for the lowest levels. Each group also produced significant (p &amp;lt; 0.05) changes in their hematological variables with maximum hemoglobin (Hb), hematocrit (Hct) content, and red blood cell (RBC) count noted at 17.5 g kg-1 arginine diet. Although the majority of blood plasma parameters were insignificantly (p &amp;gt; 0.05) different with respect to varied arginine fed diets, plasma aspartate transaminase (AST) showed significant (p &amp;lt; 0.05) variations across the treatments. Moreover, total protein, alkaline phosphatase (ALP) and albumin contents increased significantly (p &amp;lt; 0.05) with increasing arginine concentrations up to 17.5 g kg-1 and, thereafter, a declined trend in these parameters were noted. Intestinal enzymes and antioxidant properties showed significant (p &amp;lt; 0.05) variations, except plasma amylase, which showed insignificant variation. The maximum up-regulation of TOR and 4E-BP1 gene expression levels were found for fish fed 17.5 g kg-1 of dietary arginine compared to the lower (10.0 and 12.5 g kg-1) and higher (20.0 and 22.5 g kg-1) arginine levels, which indicates that fish utilize arginine more efficiently at this point. Quadratic regression analysis of live weight gain (LWG), feed conversion ratio (FCR), protein efficiency ratio (PER) and body protein deposition (BPD) indicated the optimal arginine requirement of rainbow trout to be 17.61 g kg-1 of dry diet, corresponding to 39.13 g kg-1 of dietary protein, which enhances growth, immunity, antioxidant ability, and also promote TOR signaling pathway in rainbow trout.

118 Awardee Talk: An Empirical Model of Essential Amino Acid Requirements in the Pregnant Sow

Abstract Amino acid (AA) requirements are generally considered to be the minimum needed for maximum growth or protein synthesis; however, multiple studies have shown that AA intakes above these requirements improve various body functions such as immune response, gut health, and reproduction. The objective of the current modeling approach was to estimate AA intake in gestation that considered protein synthesis as well as sow reproductive performance and offspring development, potentially increasing piglet growth and survivability. A literature review was conducted to identify studies evaluating the effects of sow AA intake during gestation on protein synthesis, sow body weight, litter size, average piglet birth weight and suckling piglet growth rate. Data from 26 empirical studies from 1989 to 2021 were selected for model development and estimation of arginine, leucine, lysine, methionine, threonine, and valine requirements. To check model accuracy and performance, a validation analysis was conducted by contrasting the model predicted lysine requirements with data from 17 published studies not used in the development of the model. The estimated lysine requirement was approximately 40% greater than the minimum lysine intake required for maximum protein synthesis. Similarly, the ratios of arginine, leucine, methionine, and valine to lysine were on average 1.60, 2.47, 0.41, and 0.79, respectively, which are 6 to 300% greater than, and the ratio of threonine to lysine was similar to, current recommendations. The validation analysis showed that the estimated lysine requirement resulted in the greatest litter size and birth weight. In addition, when compared with lysine intakes that met current recommendations, lysine intake at the estimated requirement improved colostrum and milk quality, stillborn rate, proportion of low birth weight, suckling piglet growth rate, and sow blood urea, among other metabolic variables. In conclusion, at the estimated requirements sow reproductive performance as well as piglet survivability and growth rate are improved.

PSI-3 Effects of Increasing Dietary Arginine Supply on Pig Growth Performance Following Weaning Stress

Abstract Intestinal health has important implications for pig overall health status and growth performance. In this regard, arginine participates in important regulatory functions associated with nutrient metabolism, cell proliferation, and immune response that contribute to the maintenance of a functional intestinal tract. However, Current nutritional practices for weaned pigs do not consider the critical regulatory roles of arginine related to pig gut health and function. The objective of this study was to determine growth response of weaned pigs fed increasing levels of L-Arginine during the first weeks after weaning. A total of 225 weaned pigs (BW 5.8 ± 0.9 kg) were used in a randomized complete block design and assigned to 1 of 5 dietary treatments, with 9 replicate pens of 5 pigs. A basal diet was formulated to meet current arginine requirements (0.66% - NRC, 2012) and L-arginine was supplemented at 0.3, 0.6, 0.9, and 1.2%. Experimental diets were provided in meal form during phases 1 and 2 of a 3-phase nursery feeding program: Phase 1 (d 0-d 7), Phase 2 (d 8-d 21), and Phase 3 (d 22-d 42). A common diet was provided during phase 3. Feed disappearance and body weight were measured at d 7, 14, 21, and 42 after weaning. Through the first 3 weeks after weaning, increasing dietary arginine supply linearly improved (P ≤ 0.05) body weight (8.25 - 11.20 kg), average daily gain (Figure 1), average daily feed intake (251.53 - 387.75 g), and gain to feed ratio (0.60 – 0.66) of pigs. These beneficial effects persisted throughout phase 3, where arginine supplementation resulted in a linear improvement in pig overall growth performance. In addition, increasing arginine supply reduced the percentage of pigs that lost weight during the first week post-weaning by 29%. Overall, weaned pigs require more dietary arginine for optimal nursery performance, which includes reducing fall back pigs.

Arginine requirement for egg production in Japanese quail

The objective of this study was to determine the ideal arginine intake for egg production in Japanese quail using the dilution technique. A completely random design was used, with 8 treatments (seven concentrations of arginine plus a control diet) and ten replicates, totaling 80 Japanese quails. The digestible arginine levels included in the study were 0.361%, 0.603%, 0.843%, 1.084%, 1.204%, 1.311%, and 1.460%. The variables analyzed were feed intake, egg production (EP), egg weight, egg output (EO), feed conversion ratio, and body weight were performed using a mixed model. When the effect of arginine levels (P ≤ 0.05) was detected, the model's broken line linear-plateau (BL), quadratic-plateau (BLq), and the first intercept of the BLq in the plateau of BL were adjusted to determine the ideal arginine intake. It observed that the arginine levels modified the quail responses (P < 0.001). Egg production was 10% with the 0.361% arginine in diet and recovered (97%) with the 1.311% arginine diet. The BL and BLq models estimated 232 mg/quail per day and 351 mg/quail per day for EO, respectively. The first intercept obtained was 290 mg/quail per day or 1,411%, which was considered the optimum level arginine intake for EO in Japanese quail.

Effects of Dietary Arginine on Growth Performance, Digestion, Absorption Ability, Antioxidant Capability, Gene Expression of Intestinal Protein Synthesis, and Inflammation-Related Genes of Triploid Juvenile Oncorhynchus mykiss Fed a Low-Fishmeal Diet

In this study, the effects of arginine on growth, serum antioxidant levels, intestinal digestion physiology, intestinal protein synthesis, and expression of inflammatory-related genes of triploid juvenile rainbow trout (Oncorhynchus mykiss) were investigated. Five diets containing 0.86%, 1.65%, 2.10%, 2.85%, and 3.50% arginine were fed to satiation to triplicate groups of 30 fish per tank for 8 weeks. The results showed that the weight gain rate, specific growth rate, and protein efficiency ratio significantly increased. The optimal dietary arginine requirement was 2.48% (5.97% of dietary protein) based on quadratic regression analysis between specific growth rate and dietary arginine content. There were no significant differences in crude lipid and ash content. Moisture significantly decreased, and crude protein content significantly increased ( P &lt; 0.05 ). Superoxide dismutase, catalase, and lysozyme levels in serum and the liver first significantly increased and then decreased with the level of arginine compared to the control group ( P &lt; 0.05 ), while the malondialdehyde level significantly decreased. Intestinal lipase and amylase levels significantly increased, but there was no significant difference in trypsin level ( P &gt; 0.05 ). The muscular layer thickness and villus width foregut in the 2.85% group were significantly increased. TOR at 2.86% and IGF-1 and S6K1 at 2.11% reached the maximum level, and IL-1β, IL-6, and IL-8 showed a decreasing trend with their lowest levels in the 3.50% and 2.85% groups. The expression of TNF-α first decreased and then increased with the arginine level. Both TGF-β and IL-10 expression first decreased and then increased with the level of arginine and reached the maximum value in the 2.85% group. NF-κB showed an opposite trend and reached the lowest value in the 3.50% group. In conclusion, dietary arginine has a significant effect on growth, serum antioxidant capability, digestion physiology, immunity, digestion, and absorption of nutrients in triploid O. mykiss, and the optimum requirement is 2.48% fed a low-fishmeal diet.

Lysine and arginine requirements of male and female broiler in the starter, grower, and finisher phase

Twelve dose-response trials were conducted to estimate lysine (Lys) and arginine (Arg) requirements of male and female broilers in the starter (1–14 days of age), grower (15–28 days of age), and finisher (29–42 days of age) phase. In each trial, 640 birds were randomly assigned to one of eight treatments (Lys or Arg levels) with four replicates of 20 birds. In Lys trials, for both sexes, digestible (dig) Lys concentration in feeds ranged from 8.73 to 17.5 g/kg in the starter phase, 7.80–15.7 g/kg in the grower phase, and 6.40–12.8 g/kg in the finisher phase. In Arg trials, for both sexes, the dietary dig Arg concentrations investigated ranged from 10.9 to 18.7 g/kg in the starter phase, 8.38 a 16.8 g/kg in the grower phase, and 6.85–13.7 g/kg in the finisher phase. Performance and protein gain (PG) data were fitted to linear-response plateau (LRP), curvilinear-response plateau (CRP), and quadratic polynomial (QP) regression models to estimate the dig Lys and Arg intake required to optimize the responses assessed. For each phase, average daily gain (ADG) was maximized at 0.415, 1.38, 1.79 g dig Lys/day and 0.457, 1.48, and 2.11 g dig Arg/day in male broiler chickens and 0.415, 1.21, and 1.40 g dig Lys/day and 0.446, 1.34, and 1.89 g dig Arg/day in female. For male birds, PG was maximum at 0.496, 1.63, and 1.72 g dig Lys/day, whereas for female birds, maximum values were 0.528, 1.30, and 1.80 g dig Lys/day. In Arg trials, maximum protein gain was reached at 0.518, 1.36, and 2.29 g dig Arg/day in male, and 0.474, 1.28, and 2.03 g Arg/day in female, respectively. The Lys and Arg values reported in this study may be used as a reference to formulate feeds and achieve a maximum response.

Modelling Broiler Requirements for Lysine and Arginine.

Simple SummaryAchieving a close balance between amino acids provided by feeds and the estimated requirements of broilers is crucial to increase the economic and environmental efficiency in intensive poultry rearing. The utilization of factorial models to predict amino acid requirements requires previous knowledge of the efficiency with which such amino acids are utilized for growth. This study aimed to investigate broiler responses to lysine (Lys) and arginine (Arg) and, based on such responses, to estimate the efficiency with which birds utilize both amino acids for growth. Once estimated, the efficiency values were used to develop two factorial models to predict broiler intakes of Lys and Arg. Overall, the utilization efficiencies were calculated as 0.79 and 0.62 for digestible lysine and arginine intake, respectively. Based on such efficiencies, the male and female broiler requirements for digestible lysine and arginine to deposit 1 g of body protein were 94.9 and 92.9 mg, respectively.Six assays were conducted to investigate male and female broiler responses to standardized ileal digestible (SID) lysine (Lys) and arginine (Arg). Response data were modeled to estimate the efficiency of utilization (k) of both amino acids and adjust factorial models to predict bird intake for SID Lys and SID Arg. In each assay, 1280 Cobb 500® broilers (640 male and 640 female) were randomly assigned to one of sixteen dietary treatments with four replicates of 20 birds. Dietary treatments consisted of crescent levels of SID Lys or SID Arg based on the dilution technique. The values of k determined for each phase (1- to 14-, 15- to 28-, and 29- to 42-d-old) and sex were contrasted using linear regression with groups (sex and phase). The estimated efficiencies were 0.79 for Lys and 0.62 for Arg, which were unaffected by phase or sex. Factorial models based on body weight and weight gain (M1) and on body and feather protein weight and deposition (M2) were applied to estimate the SID Lys and Arg intake for growth. The amino acid intake based on M2 had a lower error of prediction. Broiler chickens require 94.9 and 92.9 mg/d of SID Lys and SID Arg to deposit 1 g of body protein.

Advances in practical feed formulation and adoption for hybrid grouper (Epinephelus fuscoguttatus♀ × E. lanceolatus♂) aquaculture

AbstractGrouper aquaculture is currently trending towards production of hybrids, due to their improved growth and disease resistance. The predominant cross is between tiger grouper (Epinephelus fuscoguttatus) females and giant grouper (Epinephelus lanceolatus) males (TGGG). Sustainable TGGG aquaculture development is limited by reliance on wild‐caught ‘trash’ fish as feed rather than commercially formulated feeds. Specific TGGG nutrient requirement values remain limited, especially for larger fish that consume the highest volumes of feed. This limits the effectiveness of formulated feeds to provide optimal growth and feed conversion in an economically efficient manner. This review examines the current knowledge of hybrid grouper nutrient requirements for grow‐out feeds and identifies knowledge gaps to inform further research that will enable development of cost‐effective feeds that optimize fish growth, feed conversion and health. Current best practice in TGGG feeds specifies a relatively high protein requirement (53.5% crude protein), with higher arginine and lower lysine requirements than previously reported for grouper species. Like other groupers, the hybrid appears to require low lipid levels (10–14%); however, it remains to be elucidated whether this increases significantly with body size. The nutrient requirement data within this review provide a starting point for development of specific hybrid grouper feeds. However, commercialization of such feeds requires better understanding of the socio‐economic context of the target industry. While formulated feeds may be more cost‐effective, their implementation is limited by inferior growth compared with ‘trash’ fish. Performance gains are expected through increased understanding of size‐specific nutrient requirements and specific raw material quality criteria.

Arginine metabolism and its functions in growth, nutrient utilization, and immunonutrition of fish

Fish have limited ability in endogenous biosynthesis of arginine. Arginine is an indispensable amino acid for fish, and the arginine requirement varies with fish species and fish size. Recent studies on fish have demonstrated that arginine influences nutrient metabolism, stimulates insulin release, is involved in nonspecific immune responses and antioxidant responses, and elevates disease resistance. Specifically, arginine can regulate energy homeostasis via modulating the adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) pathway, and also regulate protein synthesis via activating the target of rapamycin (TOR) signaling pathway. The present article reviews pertinent knowledge of arginine in fish, including dietary quantitative requirements, endogenous anabolism and catabolism, regulation of the endocrine and metabolic systems, and immune-regulatory functions under pathogenic challenge. Our findings showed that further data about the distribution of arginine after intake into specific cells, its sub-cellular sensor to initiate downstream signaling pathways, and its effects on fish mucosal immunity, especially the adaptive immune response against pathogenic infection in different species, are urgently needed.

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 levels on growth, immune function of physical barriers and serum parameters of spotted seabass (Lateolabrax maculatus) reared at different water temperatures

A growth experiment was conducted to investigate the effects of dietary arginine levels on growth, immune function of physical barriers and serum parameters of spotted seabass (Lateolabrax maculatus) reared at different water temperatures (27°C and 33°C). Six iso‑nitrogenous and iso‑lipid diets were formulated with 1.16%, 1.65%, 2.04%, 2.44%, 2.98% and 3.36% arginine, respectively. Growth of fish reared at 27°C was significantly higher than that of fish reared at 33°C (P < 0.05). Weight gain (WG) increased first and then decreased with the increase of arginine levels, and the maximum value was obtained in fish fed the diet with 2.04% arginine at 27°C or 33°C. As for immune function of physical barriers, activities of antioxidant enzymes (GPx and SOD) and expression of genes related to tight junction (ZO-1, Occludin and Claudin b) were significantly higher in the gills of fish reared at 27°C than those of fish reared at 33°C (P < 0.05). Furthermore, activities of GPx and SOD and the mRNA expression of ZO-1, Occludin and Claudin b reached the maximum values in the gills of fish fed the diet with 2.44% or 2.04% arginine at 27°C among all treatments. The mRNA expression of MAPK p38 and MyD88 and contents of pro-inflammatory cytokines (IL-1β, IL-6 and TNFα) were significantly lower in the intestine of fish reared at 27°C than those of fish reared at 33°C (P < 0.05). Regardless of water temperature, contents of IL-1β, IL-6 and TNFα as well as the mRNA expression of MAPK p38 and MyD88 reached the minimum values in the intestine of fish fed the diet with 2.04% or 2.44% arginine at 27°C among all treatments. As for serum parameters, the activity of iNOS as well as contents of NO, complements 3 and 4 were significantly higher in fish reared at 27°C than those of fish reared at 33°C (P < 0.05). Regardless of water temperature, serum activities of TNOS and iNOS reached the maximum values in fish fed the diet with 2.04% or 2.44% arginine among different arginine supplementation groups. The activity of lysozyme reached the maximum value in fish fed the diet with 2.04% arginine level at 27°C among all treatments. Those results showed that a water temperature of 33°C decreased growth, immune function of physical barriers and serum parameters of fish. Growth and immunity were maximized when the arginine requirement of spotted seabass was met. Second-order polynomial regression analyses of WG and lysozyme activity showed that the arginine requirement of spotted seabass was 2.47% and 2.53% of the dry diet (5.49% and 5.62% of dietary protein) at 27°C as well as 2.40% and 2.37% of the dry diet (5.33% and 5.27% of dietary protein) at 33°C, respectively.

Arginase II Plays a Central Role in the Sexual Dimorphism of Arginine Metabolism in C57BL/6 Mice

Sex differences in plasma concentration of arginine and arginase activity of different tissues have been reported in mice. In addition, male but not female C57BL/6 mice have a dietary arginine requirement for growth. The goal of this research was to test the hypothesis that arginase II is a key factor in the sexual dimorphism of arginine metabolism. Young adult male and female wild type (WT), and heterozygous and arginase II knockout mice on a C57BL/6 background mice were infused with labeled citrulline, arginine, ornithine, phenylalanine, and tyrosine to determine the rates of appearance and interconversion of these amino acids. Tissue arginase activity was measured in the liver, heart, jejunum, kidney, pancreas, and spleen with an arginine radioisotope. The effect of genotype, sex, and their interaction was tested. Female mice produced ∼36% more citrulline than their male littermates, which translated into a greater arginine endogenous synthesis, flux, and plasma concentration (42, 6, and 27%, respectively; P< 0.001). Female mice also had a greater phenylalanine flux (10%) indicating a greater rate of whole protein breakdown; however, they had a lower protein synthesis rate than males (18%; P< 0.001). The ablation of arginase II reduced the production of citrulline and the de novo synthesis of arginine in females and increased the rate of appearance of arginine and plasma arginine concentration in male mice (16 and 22%, respectively; P< 0.001). No effect of arginase II deletion, however, was observed for whole-body protein kinetics. Arginase II activity was present in the pancreas, kidney, jejunum, and spleen; WT females had a ∼2-fold greater renal arginase activity than their WT counterparts. A clear sexual dimorphism exists in the endogenous synthesis of arginine and its disposal. Female mice have a greater arginine availability than their male littermates. The ablation of arginase II increases arginine availability in male mice.