Whole-body Crude Protein Content Research Articles

Dietary Supplementation of Astragalus membranaceus Extract Affects Growth Performance, Antioxidant Capacity, Immune Response, and Energy Metabolism of Largemouth Bass (Micropterus salmoides).

The present study investigated the effects of Astragalus membranaceus extract (AME) on growth performance, immune response, and energy metabolism of juvenile largemouth bass (Micropterus salmoides). Seven diets containing 0%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, and 0.6% AME (Con, AME0.1, AME0.2, AME0.3, AME0.4, AME0.5, and AME0.6 groups) were formulated and fed to M. salmoides for 8 weeks. Final body weight (FBW), feed intake (FI), weight gain (WG), and specific growth rate (SGR) were all significantly higher in AME0.4 group than in Con group (P < 0.05). Feed conversion rate (FCR) was significantly improved in AME0.5 group compared with Con group (P < 0.05). Whole-body crude protein contents were significantly increased in AME0.2 group (P < 0.05). Whole-body crude lipid contents were significantly lower in AME0.2 and AME0.3 groups, while muscle lipid was upregulated by dietary AME (P < 0.05). Hepatic malondialdehyde (MDA) contents were significantly lowered in AME0.3 and AME0.4 groups, and catalase (CAT) activities were significantly increased in AME0.1 and AME0.2 groups (P < 0.05). Plasma aspartate aminotransferase (AST) level was significantly lowered in AME0.5, and AME0.6 groups, and alanine aminotransferase (ALT) level was lowered in AME0.5 groups (P < 0.05). Plasma triglyceride was declined in AME0.6 group, and glucose was decreased by 0.3%-0.5% AME (P < 0.05). Significantly higher hepatocyte diameter, lamina propria width, and submucosal layer thickness were recorded in AME0.6 groups, while the longest villi height was obtained in AME0.2 and AME0.3 groups (P < 0.05). The mRNA expression levels of insulin-like growth factor 1 (igf1) revealed the growth-promoting effect of AME. The anti-inflammatory and antiapoptotic effects of AME were demonstrated by transcription levels of interleukin 8 (il-8), tumor necrosis factor-alpha (tnf-a), caspase, B-cell lymphoma-xl (Bcl-xl), bcl-2 associated x (Bax), and bcl-2-associated death protein (Bad). The transcription levels of lipid metabolism and gluconeogenesis related genes, including acetyl-CoA carboxylase alpha (acc1), fatty acid synthase (fasn), fatty acid binding protein 1 (fabp1), phosphoenolpyruvate carboxykinase 2 (pepck2), and glucose-6-phosphatase catalytic subunit 1a (g6pc), were reduced by AME treatment, while the levels of glycolysis-related genes, including glucokinase (gck) and pyruvate kinase (pk), were the highest in AME0.2 and AME0.3 groups (P < 0.05). According to polynomial regression analysis of SGR, WG, FCR, whole-body crude lipid, MDA, and ALT, the optimal AME supplementation level was estimated to be 0.320%-0.429% of the diet. These results provided insights into the roles of AME in regulating immunity and metabolism, which highly indicated its potential as immunostimulants and metabolic regulators in diverse aquatic animals.

Dietary L-Lysine Requirement of Coho Salmon (Oncorhynchus kisutch) Alevins

The suitable dietary L-lysine concentration for coho salmon (Oncorhynchus kisutch) alevins was assessed by a dose response feeding trial. Six experimental diets were made with graded L-lysine concentrations of 2.29%, 2.81%, 3.32%, 3.80%, 4.27%, and 4.78% of the dry matter, respectively, each of which was fed to triplicate groups of 100 alevins (initial body weight: 0.30 ± 0.01 g) in 18 plastic baskets (water volume 240 L). The alevins were cultured in a flowing freshwater system and fed manually to apparent satiation four times a day for 12 weeks. The survival rate of alevins did not differ significantly among the dietary groups. The specific growth rate (SGR), protein efficiency ratio (PER), and body protein deposition (BPD) increased significantly (p &lt; 0.05) with the increase in dietary lysine concentration up to 3.80% and then reduced as lysine level further increased. The feed conversion ratio (FCR) had an inverse trend to SGR. The whole-body crude protein content of the alevins increased significantly with increasing dietary lysine level, while crude lipid content showed the opposite trend. In comparison, the contents of morphological indices, whole-body moisture, and ash were not affected significantly (p &gt; 0.05) by the different dietary lysine concentrations. The highest contents of lysine, arginine, and total essential amino acids (EAAs) were observed in the group with 4.27% dietary lysine concentration, which did not differ significantly from those in the 3.32%, 3.80%, and 4.78% groups but was significantly higher than those in the 2.29% and 2.81% groups. Similarly, valine had the highest content in the group with 4.78%. The variations in dietary lysine had no significant impacts on other EAA and non-EAA contents except glycine, which increased with increasing dietary lysine level. Second-order polynomial model analyses based on SGR, PER, BPD, and FCR evaluated the optimum L-lysine requirements of coho salmon alevins as 3.74%, 3.73%, 3.91%, and 3.77% of the diet or 6.80%, 6.78%, 7.11%, and 6.85% of dietary proteins, respectively.

Optimal dietary lysine improves the growth performance, molting frequency, lipid metabolism, immunity and antioxidant of postlarval mud crab Scylla paramamosain

A 56-day feeding trial was designed to investigate the effect of different dietary lysine (Lys) levels on the growth, molting, lipid metabolism, antioxidant, and immunity of postlarva Scylla paramosain. Six diets with 1.20%, 1.46%, 1.84%, 2.06%, 2.35%, and 2.67% Lys levels (dry matter) were formulated and experimented on the postlarva Scylla paramamosain. The results showed that Scylla paramamosain fed with the 2.06% lysine obtained the highest growth performance and the highest molting frequency. Appropriate dietary Lys levels (1.73–2.03%) can improve the antioxidant capacity of Scylla paramamosain. Although unaffected by dietary Lys, the whole-body lipid content of the 1.20% Lys group was numerically higher than those of the 1.46–2.67% Lys groups. The variation in whole-body crude protein content showed a similar trend with those in the content of EAA and NEAAs, with the highest whole-body crude protein content appearing in the 2.06% Lys group. The crabs obtained the highest expression of igf, fas, EcR and fabp genes in the 2.06% Lys group. When dietary Lys levels were > 1.20%, the transcription level of immune related-genes increased. As suggested by the results of the second order polynomial regression analysis of weight gain, the Lys requirement of postlarva Scylla paramamosain is 2.03% (4.51% of dietary protein).

Impact of dietary zinc on the growth performance, histopathological analysis, antioxidant capability, and inflammatory response of largemouth bass Micropterus salmoides

Zinc plays a crucial role in the antioxidant capacity, and inflammatory response of aquatic species, but its impact on largemouth bass Micropterus salmoides is rarely reported. Therefore, this paper aimed to investigate the effects of different levels of zinc on the growth performance, histopathology, antioxidant capacity, and inflammatory cytokines of largemouth bass Micropterus salmoides. Fish with an initial weight of 7.84 ± 0.06 g were cultured for 10 weeks. Five experimental diets were prepared with supplemented proteinate Zn (Bioplex Zn, Alltech) (0, 30, 60, 90, and 120 mg/kg), which were named the Zn-42, Zn-73, Zn-103, Zn-133, and Zn-164 groups. No evident difference was found between the dietary zinc level and the survival rate, the crude lipid content of the whole fish, or the visceral somatic index. Weight gain, condition factor, whole-body crude protein content, interleukin-10, and transforming growth factor beta gene expression were gradually enhanced with up to 102.68 mg/kg zinc and decreased at higher levels. The hepatosomatic index, feed conversion ratio, malondialdehyde level in the liver, aspartate aminotransferase, and alanine transaminase activity in the serum, gradually decreased up to 102.68 mg/kg zinc, and gradually increased beyond this. Activation of the nuclear factor erythroid-derived 2-like 2/Kelch-like ECH-associated protein 1 signaling pathway gradually up-regulated the mRNA levels and activities of glutathione peroxidase, total antioxidant capacity, catalase, and superoxide dismutase in the liver, this antioxidant ability was lower when the zinc was greater than 102.68 mg/kg. The gene expressions of nuclear factor-k-gene binding and pro-inflammation cytokines (interleukin-1β, interleukin-15, tumor necrosis factor alpha, and interleukin-8) were up-regulated up to 102.68 mg/kg zinc and then gradually repressed. In conclusion, using broken line analysis to estimate weight gain and Zn proteinate as the zinc source, the recommended dietary zinc for largemouth bass is 66.57 mg/kg zinc.

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.

Assessment of Fish Protein Hydrolysates in Juvenile Largemouth Bass (Micropterus salmoides) Diets: Effect on Growth, Intestinal Antioxidant Status, Immunity, and Microflora.

Varying dietary inclusion levels of fish protein hydrolysates (FPH) were applied in a feeding experiment with juvenile largemouth bass (Micropterus salmoides) to assess their effects on growth, intestinal antioxidant status, immunity, and microflora. FPH were added in 4 dietary levels: 0 g/kg (control group, FPH-0), 10 g/kg (FPH-10), 30 g/kg (FPH-30), and 50 g/kg (FPH-50) dry matter, respectively substituting 0, 5.3, 16.3, and 27.3% of fish meal with dietary fish meal. Quadruplicate groups of 25 juvenile largemouth bass with initial body weight 9.51 ± 0.03 g were fed during the 56-day feeding experiment. Experimental results showed that fish fed FPH-30 obtained a significantly higher weight gain rate (WGR), specific growth rate (SGR), protein efficiency ratio (PER), and significant feed conversion rate (FCR) compared to the other three groups (P < 0.05). FPH-30 group also promoted protein synthesis and deposition, as evidenced by the higher whole-body crude protein contents, the higher expressions of GH1, IGF-1, TOR, and S6K in the liver, and SLC7A5, SLC7A8, SLC38A2, and SLC15A2 in the intestine than the other three groups. FPH-30 group could also enhance intestinal health status by increasing the activities of SOD, POD, CAT, GSH-Px, and T-AOC activities by upregulating the expressions of SOD, GSH-Px, IL1β, and TNFβ, and by reducing the MDA contents and the expressions of IL15, Caspase 3, Caspase 9, and Caspase 10 than other groups. Compared to the control group, the Actinobacteriota abundance markedly decreased in FPH treatments, while the variation tendency of the phylum Proteobacteria was opposite. The peak value of Firmicutes:Bacteroidetes ratio and the lowest of Bacteroidetes abundance were seen in largemouth bass fed FPH-30 (P < 0.05). Fish in three FPH treatments had lower abundances of opportunistic pathogens Staphylococcus and Plesiomonas than fish in the control group. In conclusion, FPH is a nutritious feed ingredient for juvenile largemouth bass, and can be added to a dietary level of 30 g/kg dry matter replacing fish meal without any negative effect on growth and feed utilization. FPH supplements could also strengthen the intestinal immune mechanisms of largemouth bass to tackle the immunodeficiency produced by fish meal replacement.

Dietary L-Carnitine Alleviates the Adverse Effects Caused by Reducing Protein and Increasing Fat Contents in Diet Juvenile Largemouth Bass (Micropterus salmoides)

Protein ingredients for formulation of fish feeds are expensive and have limited availability. Therefore, reducing dietary protein while increasing dietary fat content is a common practice in rearing carnivorous fish species. However, the ability of dietary L-carnitine to alleviate adverse effects in such diets is currently unknown. This study investigated the role of L-carnitine supplementation in alleviating adverse effects on growth performance, energy metabolism, antioxidant capacity, and inflammation response in juvenile largemouth bass (Micropterus salmoides) fed on a low protein and high fat diet. Three diets were formulated to contain low protein and high fat (LPHF: 420 g kg-1 protein and 150 g kg-1 lipid), LPHF supplemented with L-carnitine (LPHFC: 420 g kg-1 protein and 150 g kg-1 lipid), and a control diet (CON: 480 g kg-1 protein and 130 g kg-1 lipid). The diets were fed to 30 largemouth bass ( 10.75 ± 0.01 g) juveniles in triplicates for eight weeks. The results showed that the fish feed on LPHF diet increased hepatosomatic index, visceral somatic index, mesenteric fat index, whole-body crude fat content, serum and liver triglyceride concentrations, and serum non-esterified fatty acid level than those fed on CON diet. Moreover, the fish fed on LPHF diet increased serum alanine aminotransferase activity and liver malondialdehyde content and reduced superoxide dismutase (SOD) activities in the serum and liver. Furthermore, the fish fed on LPHF diet reduced the whole-body crude protein content. Interestingly, feeding the fish on the LPHFC diet decreased fat deposition and liver damage by downregulating the expression of genes related to lipogenesis, inflammation, and increased SOD activity. This study indicates that L-carnitine supplementation in largemouth bass alleviates the adverse effects caused by LPHF diet by decreasing lipogenesis and increasing lipid catabolism. Our study provides novel knowledge on strategies to improve utilization of LPHF diet in cultured aquatic animals.

Complete Replacement of Fishmeal With Plant Protein Ingredients in Gibel Carp (Carassius auratus gibelio) Diets by Supplementation With Essential Amino Acids Without Negative Impact on Growth Performance and Muscle Growth-Related Biomarkers

This study was conducted to investigate the effects of substitution of dietary fishmeal (FM) by compound plant protein supplemented with essential amino acids on growth performance, plasma physiology, and muscle growth-related genes of gibel carp (Carassius auratus gibelio). Four diets with equal digestible protein were prepared, where 30FM (control feed) contained 30% FM and land animal protein as a protein source, 10FM contained 10% FM, PMAa contained full plant meal (PM) supplemented with crystalline amino acid, and PM contained full PM feed. There was no significant difference in the specific growth rate (SGR) with 30FM, 10FM, and PMAa diets (p &amp;gt; 0.05); however, the SGR of PM group was the lowest with significant difference (p &amp;lt; 0.05). Feed efficiency of the PM group was the lowest with significant difference (p &amp;lt; 0.05). The whole-body crude protein content of fish in PMAa group was significantly higher than that in each group with additional FM (p &amp;lt; 0.05). There were no significant differences in plasma total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C) or low-density lipoprotein cholesterol (LDL-C), and free amino acid profile of 30FM, 10FM, and PMAa groups (p &amp;gt; 0.05); however, they were significantly higher than that in PM group (p &amp;lt; 0.05). The expression of key genes in the TOR signaling pathway (tor, s6k1, 4e-bp2, and eif4e), autophagy (ulk1 and atg13), and ubiquitin–proteasome (trim63 and znrf2) system of the PMAa group was similar to that of the FM group (p &amp;gt; 0.05), indicating that the muscle growth-related biomarker genes were positively regulated by the appropriate dietary amino acid composition at the transcriptional level. These results suggest that FM in gibel carp diet can be totally replaced by PM without negative impact on growth performance and muscle growth-related biomarkers at the transcriptional level, which provided the requirement of digestible protein and balanced amino acid profile is satisfied.

Influence of dietary protein levels on growth, feed utilization, body indices and serum profile of silver moony Monodactylus argenteus

Monodactylus argenteus, is a high-value euryhaline ornamental fish having a good market demand. Information about its nutrient requirement, especially protein, is essential for feed formulation to maintain good health, growth and colouration. A 3-month feeding trial on the fry of this species was carried out to evaluate the effect of varying dietary protein levels on growth, body indices, serum profile, skin carotenoid content and body composition. Hatchery-produced fry (ABW: 0.73 ± 0.08 g) were randomly distributed into 18 glass tanks (90 L water each) in a recirculatory aquaculture system (RAS) @ 10 fry per tank. Five isolipidic micro-diets (75 g kg−1) with graded levels of crude protein (CP) viz. 250 (CP25), 300 (CP30), 350 (CP35), 400 (CP40), and 450 (CP45) g kg−1 were formulated and fed to satiation twice daily. At the end of the trial, weight gain (WG), specific growth rate (SGR) and protein efficiency ratio (PER) of fish fed with CP35, CP40 and CP45 diets were observed to be significantly higher compared to those fed with CP25, and CP30 diets. Protein efficiency ratio (PER) decreased with increased dietary protein levels. The viscerosomatic index (VSI) and hepatosomatic index (HSI), exhibited a decreasing trend as the level of crude protein increased. The IPF was directly proportional to the dietary crude protein content of the diet, the maximum value being obtained in the CP45 treatment. The whole-body crude protein content showed an increasing trend with the increment in dietary protein level up to the CP40 diet and the diet with the highest crude protein exhibited the lowest whole body crude protein content. Analysis of serum profile revealed that serum triglycerides, glucose and protein levels were significantly different (P < 0.05) among the treatments. The group fed with CP40 recorded the highest concentration of carotenoids which was not significantly different from CP30 and CP35 groups. The whole body amino acids profile showed a significant variation in alanine, serine, threonine, glutamine and glycine. Broken-line regression analysis revealed that the optimum dietary protein level was in the range of 325–349 g kg−1 for maximum growth of silver moony fry. Our study revealed that a minimum of 35% protein in the diet of silver moony fry is optimal for improved growth.

Bacillus subtilis LCBS1 supplementation and replacement of fish meal with fermented soybean meal in bullfrog (Lithobates catesbeianus) diets: Effects on growth performance, feed digestibility and gut health

Two consecutive feeding trials were conducted to evaluate the effects of Bacillus subtilis LCBS1 supplementation and substituting fish meal (FM) with fermented soybean meal (FSM) in terms of growth performance, feed digestibility, intestinal morphology, and microbial composition of bullfrogs. In trial 1, bullfrogs received either a soybean meal (SM)-based basal diet (control check, CK group) or probiotic diet (basal diet was supplemented with 1 × 107 CFU/g of B. subtilis LCBS1, BS group). Each diet was fed to three replicates of bullfrogs (29.61 ± 0.07 g) for 58 days. Evaluation of B. subtilis LCBS1 FSM as a FM replacer in bullfrog diet was conducted in trial 2. A diet containing 20% FM formed the basal diet, and 60% and 100% of the FM was replaced with SM or FSM (FM, SM60, FSM60, SM100, and FSM100 diets). Each diet was fed to three replicates of bullfrogs (23.3 ± 0.3 g) for 63 days. As a result, in trial 1, BS treatments significantly increased weight gain (WG) and whole-body protein deposition. Significant improvements in villus height (VH), muscularis thickness (MT), and digestibilities of dry matter (DM), crude protein (CP) and phosphorus (P) were observed in the BS group compared with the control group. Probiotic supplementation resulted in elevated IL-4 and IL-10 expression and decreased TNF-α and IL-17 expression. A remarkable decrease in serum D-lactate concentration and diamine oxidase activity was detected in the BS group. Proteobacteria, Fusobacteria, and Firmicutes were the three most abundant bacterial phyla in each group, while Enterobacter and Bacillus were the most abundant genera in the CK and BS groups, respectively. In trial 2, compared with bullfrogs that received the SM diets, bullfrogs fed either the FM or FSM diets showed greater WG, feed efficiency, hind leg index, whole-body CP content, and digestibilities of DM, CP, calcium, P, and phytate P, and increased VH, villus thickness, and MT. Serum urea nitrogen and ammonia concentrations were significantly higher in the SM group than the FM or FSM group. Overall, dietary B. subtilis LCBS1 supplementation improved growth and digestion in bullfrogs and attenuated the intestinal structural damage and microflora dysbacteriosis caused by SM-based diets. Substituting 60–100% of FM with SM impaired the growth performance, digestion ability, and jejunal morphology of bullfrogs, while replacing equivalent FM with FSM effectively ameliorated these traits.

Effects of dietary glycinin on the growth performance, immunity, hepatopancreas and intestinal health of juvenile Rhynchocypris lagowskii Dybowski

This study was to evaluate the effects of glycinin on the growth, digestion, immune function, antioxidant capacity, and hepatopancreas and intestinal morphology of juvenile Rhynchocypris lagowskii Dybowski (R. lagowskii Dybowski). Graded levels (0, 10, 20, 40 and 80 g/kg) of isolated glycinin were added to the basal diets to formulate five experimental diets containing 0.0, 7.6, 15.5, 30.8 and 60.4 g/kg immunologically active glycinin, respectively. Five diets were used to feed R. lagowskii Dybowski for 8 weeks. Results showed that the weight gain rate and specific growth rate of fish were significantly reduced by dietary 40–80 g/kg glycinin (P < 0.05), and dietary 80 g/kg glycinin significantly reduced the feeding rate, protein efficiency rate and feed efficiency rate (P < 0.05). Protease activity of hepatopancreas and intestine, and whole-body crude protein content were significantly reduced by dietary 40–80 g/kg glycinin (P < 0.05). In serum, dietary 40–80 g/kg glycinin significantly reduced lysozyme and alkaline phosphatase activities, and complement 3 and immunoglobulin M contents (P < 0.05); while significantly increased the diamine oxidase activity, D-lactic acid and endothelin-1 concentration (P < 0.05). In mid intestine, distal intestine and hepatopancreas, dietary 40–80 g/kg glycinin significantly up-regulated interleukin-1β and tumour necrosis factor-α mRNA levels (P < 0.05), and down-regulated transforming growth factor-β and interleukin-10 mRNA levels (P < 0.05); dietary 40–80 g/kg glycinin significantly reduced catalase, glutathione peroxidase and total superoxide dismutase activities (P < 0.05), and increased malondialdehyde content (P < 0.05). Furthermore, dietary 40–80 g/kg glycinin destroyed the morphological structure of intestine, including atrophy and breakage of mucosal fold. Similarly, typical characteristics of hepatopancreas damage were observed when 40–80 g/kg glycinin was added, including increased the lipid vacuoles, and the nucleus shifted, dissolved and disappeared. Concluded, dietary 40–80 g/kg glycinin induced inflammation and oxidative damage, weakened immune and digestive functions, and ultimately inhibited the growth of R. lagowskii Dybowski

Dietary folic acid improved growth performance, immuno-physiological response and antioxidant status of fingerling Siberian sturgeon, Acipenser baerii (Brandt 1896)

To investigate the effect of dietary folic acid (FA) on growth performance, proximate composition, blood parameters, antioxidant status, and immune response of Siberian sturgeon, Acipenser baerii, six isonitrogenous and isolipidic experimental diets were formulated to contain graded levels of FA (0.60, 1.63, 2.71, 3.59, 4.82, and 5.68 mg kg−1). Each diet was fed to triplicate groups of fish (4.36 ± 0.18 g) in a flow through water system for 8 weeks. Weight gain ratio (WGR) and specific growth rate (SGR) were thrived with increasing FA level up to 2.71 mg kg−1 and decreased gradually thereafter (P < 0.05). The whole-body crude protein content was also highest in fish fed with 2.71 mg FA kg−1 diet followed by those fed 3.59 and 1.63 mg FA kg−1 diet. The muscle and liver FA concentrations were enhanced with increasing dietary FA supplementation with the values significantly higher in fish fed diets supplemented by equal to or more than 3.59 and 4.82 mg FA kg−1, respectively. Red blood cells (RBCs), white blood cells (WBCs), hemoglobin (Hb), hematocrit (Hct), and lymphocyte count showed significant positive correlation with dietary FA level, whereas the neutrophil count was significantly declined by enhancing dietary FA supplementation (P < 0.05). Serum superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activities were also intensified by increasing dietary FA concentration. Fish fed diets supplemented with more than 1.63 and 2.71 mg FA kg−1 had significantly higher lysozyme activity and immunoglobulin M (IgM) compared to those fed the basal diet. The dietary FA requirement of fingerling Siberian sturgeon was estimated by subjecting the SGR, crude protein content, liver FA content, and WBC count against varying levels of dietary FA which revealed the FA requirement in the range of 1.82–4.41 mg kg−1.

Comparative evaluation of processed soybean meal (EnzoMealTM) vs. regular soybean meal as a fishmeal replacement in diets of rainbow trout (Oncorhynchus mykiss): Effects on growth performance and growth-related genes

A 12-week feeding trial was conducted to compare low and high inclusions of conventional soybean meal (SBM) or enzyme-treated SBM (Enzo) as fishmeal replacements in the diets of rainbow trout, Oncorhynchus mykiss. Six isonitrogenous (43% crude protein) and isolipidic (19% crude lipid) diets were produced: a control diet (fishmeal-based) and five experimental diets replacing fishmeal by 8% or 16% with SBM (low or high SBM, respectively); 8% or 16% with Enzo (low or high Enzo, respectively); and 16% with SBM + Enzo blended with 50:50 ratio (Enzo + SBM). Triplicate tanks, each containing 40 fish, were hand-fed to apparent satiation. Compared with the control, all groups that consumed SBM or Enzo diets had lower growth performance (P < 0.05). However, fish fed Enzo showed significantly higher growth performance and protein retention than fish fed SBM at each replacement level. Whole-body crude protein content showed a decreasing trend with increasing dietary SBM and Enzo level, with significant differences detected between the control and the highest SBM or Enzo + SBM levels. However, fish fed control or low Enzo diets had no significant differences (P > 0.05). Whole-body content of some essential amino acids (e.g. isoleucine, leucine and valine) showed a significant corresponding decrease with high dietary SBM inclusions. Trypsin activity in the proximal intestine decreased significantly with increasing dietary SBM and Enzo levels. Hepatic expression of GHR1 was greater in high SBM and high Enzo + SBM treatments compared to the control diet, which exhibited the highest expression of IGF-II (P < 0.05). Expression of IGFBP-1b1 was lowest in the control treatment and highest in the high SBM diet (P < 0.05). Expression of myogenin and myoD, two myogenic proteins, was also affected by diet (P < 0.05), with highest expression in the slowest growing treatment group (high SBM). The inferior performance of rainbow trout fed SBM compared to Enzo was likely due to reduced feed intake and nutrient availability leading to alternations in the somatotrophic axis. Thus, Enzo shows promise as an alternative to SBM in rainbow trout diets.

Dietary arginine requirement of juvenile hybrid sturgeon (Acipenser schrenckii♀ × Acipenser baerii♂)

An 8-week feeding trial was conducted to evaluate the dietary arginine requirement of juvenile hybrid sturgeon. Seven isonitrogenous and isolipidic diets were formulated to contain graded levels of dietary arginine ranging from 1.74% to 3.54% (dry weight). The results indicated that the fish fed with 1.76% arginine diet had lower specific growth rate (SGR) and feed efficiency ratio (FER) than the fish fed the 2.64% to 3.24% arginine diets (p < .05), and the fish fed the 2.64% arginine diet presented the highest SGR. The fish fed with 1.76% arginine diet had lower whole-body crude protein content than the fish fed the 2.64% or 2.93% arginine diets (p < .05). Compared with the 1.76% arginine diet, 2.36% to 2.93% arginine diets significantly increased the total amino acid (TAA) concentration and total nonessential amino acid (TNEAA) of carcasses. The fish fed with 1.76% arginine diet had lower activity of nitric oxide synthase (T-NOS) and content of nitric oxide (NO) than the fish fed the 2.05% to 2.93% arginine diets in the liver. The fish fed with 1.76%, 2.05% or 2.36% arginine diets had lower gene expression of growth hormone (GH) and insulin-like growth factor I (IGF-I) in the liver than the fish fed the 2.64% to 3.53% arginine diets in the liver (p < .05). A broken-line analysis between SGR against the dietary arginine levels provided estimates for the optimal dietary arginine requirement of 2.47% corresponding to 6.18% of the dietary protein on a dry weight basis.

Effects of Taurine Supplementation on the Growth Performance of Juvenile Rock Bream Oplegnathus fasciatus

An 8-week feeding trial was conducted to investigate the effects of dietary taurine supplementation on the growth performance of juvenile rock bream, Oplegnathus fasciatus. Triplicate groups of 25 fish averaging <TEX>$2.72{\pm}0.04$</TEX> g (<TEX>$mean{\pm}SD$</TEX>) were fed one of six experimental diets prepared by adding taurine at 0%, 0.25%, 0.5%, 1.0%, 1.5% and 3.0% (Control, <TEX>$Tau_{0.25}$</TEX>, <TEX>$Tau_{0.5}$</TEX>, <TEX>$Tau_{1.0}$</TEX>, <TEX>$Tau_{1.5}$</TEX> and <TEX>$Tau_{3.0}$</TEX>, respectively). At the end of the feeding trial, the weight gain, specific growth rate and protein efficiency ratio of fish fed the <TEX>$Tau_{0.5}$</TEX>, <TEX>$Tau_{1.0}$</TEX> and <TEX>$Tau_{1.5}$</TEX> diets were significantly higher (P < 0.05) than those of fish fed the Control and <TEX>$Tau_{0.25}$</TEX> diets. The feed efficiency of fish fed the <TEX>$Tau_{0.5}$</TEX> diet was significantly higher than that of fish fed the Control, <TEX>$Tau_{0.25}$</TEX> and <TEX>$Tau_{3.0}$</TEX> diets. Fish fed the <TEX>$Tau_{1.0}$</TEX> diet had higher whole-body crude protein content than fish fed the Control diet, while the crude lipid content of fish fed the <TEX>$Tau_{1.5}$</TEX> and <TEX>$Tau_{3.0}$</TEX> diets was significantly lower than that of fish fed the Control and <TEX>$Tau_{0.25}$</TEX> diets. An ANOVA suggested that the optimum level of dietary taurine supplementation to improve growth and reduce the body lipid contents of juvenile rock bream, O. fasciatus, was 0.5%, while a broken line analysis of weight gain indicated a level of 0.62%.

Effects of dietary amino acid patterns on growth and protein metabolism of large yellow croaker (Larimichthys crocea) larvae

This study was conducted to evaluate the effects of dietary amino acids (AA) patterns on growth, survival, activities of digestive enzymes and aminotransferases and target of rapamycin (TOR) gene expression of large yellow croaker (Larimichthys crocea) larvae. The control diet was produced using intact protein as the only protein source. Four isonitrogenous and isolipidic semi-purified diets were formulated with crystalline-AA replacing approximately 40% fish meal protein-bound nitrogen. The AA patterns of these diets were adjusted according to the overall AA pattern of large yellow croaker egg protein (LEP), large yellow croaker larvae whole-body protein (LLP), large yellow croaker muscle protein (LMP) and white fishmeal protein (WFP), respectively. The test diets and live copepod were fed to triplicate groups of larvae (initial body weight 3.15±0.15mg) five times (6:00, 8:30, 12:30, 14:30, and 17:00) daily for 30days. The results showed that specific growth rate (SGR) of fish fed the WFP diet was significantly higher than LEP or LLP diet (P<0.05). At the end of the growth trial, there was no significant difference in survival rate among larvae fed LEP, LLP, WFP and the control diet (P>0.05), whereas the highest value was recorded in larvae fed the LLP diet, followed by WFP, the control, LEP and LMP diet, respectively. Whole-body crude protein content was significantly higher in larvae fed the WFP diet compared to the LEP or LLP diet (P<0.05). Larvae fed the live copepod had significantly higher whole-body crude protein and lipid contents than that in larvae fed artificial microdiets (P<0.05). Whole-body moisture content was not significantly affected by dietary treatments (P>0.05). The specific activities of digestive enzymes and the ratio “pancreatic enzyme in intestinal segment/pancreatic enzyme in pancreatic segment” were significantly higher in fish fed the WFP diet than fish fed LLP and LEP diet (P<0.05). Specific activities of alanine and aspartate aminotransferases were significantly higher in fish fed the WFP diet compared to the other treatments (P<0.05). No significant differences were observed in larvae body TOR gene expression among dietary treatments (P>0.05). Results of this study indicated that white fishmeal protein amino acid pattern was a more suitable amino acid pattern in diets of large yellow croaker larvae compared to the amino acid pattern of LEP, LLP, and LMP.

Effects of dietary glutathione on growth performance,tissue biochemical indexes and non-specific immune related enzymes of GIFT Oreochromis niloticus

This study was conducted to investigate the effects of dietary glutathione(GSH)on growth performance,tissue biochemical indexes and non-specific immune related enzymes of GIFT Oreochromis niloticus.720 fish with initial weight of(3.27±0.04)g were randomly allocated into 6 groups.The fish in control group were fed the basal diet(G0),while those in the other five groups were fed the basal diet added with 80,160,240,320,400 mg/kg GSH.After 7 weeks' feeding,weight gain rate(WGR),specific growth rate(SGR),protein efficiency ratio(PER)and RNA/DNA ratio of liver in 320 mg/kg group were significantly higher than those in the control group(P0.05),and feed coefficient(FC)was significantly lower(P0.05).Hepatosomatic index(HSI)was higher in GSH added groups than the control,showing no significant difference(P0.05).Among all groups,no significant difference was found in condition factor(CF)(P0.05).The whole-body crude protein content and crude lipid content were significantly affected by dietary GSH levels(P0.05),while the ash and dry matter content showed no significant difference(P0.05).Serum UN content was significantly lower in 320 mg/kg group compared with the control(P0.05).The IGF-Ⅰlevel in G160-G400 mg/kg groups was significantly higher than the control and 80 mg/kg groups.The serum lysozyme(LZM)activities increased significantly in 240,320 and 400 mg/kg groups compared with the others(P0.05),and liver LZM activities were significantly higher in 320 and 400 mg/kg groups(P0.05).Dietary GSH increased serum alkaline phosphatase(AKP),phenoloxidase(PO)and liver AKP,acid phosphatase(ACP)activities,but no significant difference was shown(P0.05).Serum nitric oxide synthase(NOS)activities in 320 mg/kg group were significantly higher than the control(P0.05),but those in liver showed no significant difference(P0.05).The result suggested that dietary GSH could significantly improve growth performance,raise whole-body crude protein and crude lipid content,increase serum and liver IGF-Ⅰ level,and enhance activities of non-specific immune related enzymes in GIFT Oreochromis niloticus.The optimum level of dietary GSH was 355.13 mg/kg on the basis of WGR.

치어기 넙치 사료의 어분 대체원으로써 대두농축단백을 이용하여 생산한 오징어간분의 평가

This study determined the proper inclusion levels of squid liver powder (SLP) - soy protein concentrate (SPC) premix as a fish meal (FM) substitute in the diet for juvenile olive flounder (Paralichthys olivaceus). All the experimental diets were formulated to be isonitrogenous (50% crude protein) and isocaloric (17.1 kJ energy <TEX>$g^{-1}$</TEX> diet). Five diets were formulated with SLP-(SPC) replacing 0, 25, 50, 75, and 100% of the FM (SLP <TEX>$(SPC)_0$</TEX>, SLP <TEX>$(SPC)_25$</TEX>, SLP <TEX>$(SPC)_50$</TEX>, SLP <TEX>$(SPC)_75$</TEX>, and SLP <TEX>$(SPC)_100$</TEX>, respectively). Triplicate groups of 12 fish averaging <TEX>$5.56{\pm}0.10\;g$</TEX> (<TEX>$mean{\pm}SD$</TEX>) were fed one of the five experimental diets for 7 weeks. The weight gain (WG), specific growth rate (SGR), feed efficiency (FE), and protein efficiency ratio (PER) of fish fed SLP <TEX>$(SPC)_0$</TEX> were significantly (P<0.05) higher than those of fish fed SLP <TEX>$(SPC)_50$</TEX>, SLP <TEX>$(SPC)_75$</TEX> and SLP <TEX>$(SPC)_100$</TEX>, while those of fish fed SLP <TEX>$(SPC)_0$</TEX> and SLP <TEX>$(SPC)_25$</TEX> were similar. The whole-body crude protein content of fish fed SLP <TEX>$(SPC)_0$</TEX> was significantly (P<0.05) lower than that of fish fed SLP <TEX>$(SPC)_50$</TEX>, SLP <TEX>$(SPC)_75$</TEX>, and SLP<TEX>$(SPC)_100$</TEX>, while those of fish fed SLP <TEX>$(SPC)_0$</TEX> and SLP <TEX>$(SPC)_25$</TEX> were similar. The whole-body crude lipid of fish fed SLP <TEX>$(SPC)_0$</TEX> was significantly (P<0.05) lower than that of fish fed SLP <TEX>$(SPC)_50$</TEX> and SLP <TEX>$(SPC)_75$</TEX>, while those of fish fed SLP <TEX>$(SPC)_0$</TEX>, SLP <TEX>$(SPC)_25$</TEX> and SLP <TEX>$(SPC)_100$</TEX> were similar. Based on the fish growth performance results obtained from this study, the SLP (SPC) premix can substitute up to 25% of the FM in the diets of juvenile olive flounder.