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1.
Growth‐related traits are the main target of genetic breeding programmes in grouper aquaculture. We constructed genetic linkage maps for tiger grouper (Epinephelus fuscoguttatus) and giant grouper (E. lanceolatus) using 399 simple sequence repeat markers and performed a quantitative trait locus (QTL) analysis to identify the genomic regions responsible for growth‐related traits in F1 hybrid grouper (E. fuscoguttatus × E. lanceolatus). The tiger grouper (female) linkage map contained 330 markers assigned to 24 linkage groups (LGs) and spanned 1,202.0 cM. The giant grouper (male) linkage map contained 231 markers distributed in 24 LGs and spanned 953.7 cM. Six QTLs affecting growth‐related traits with 5% genome‐wide significance were detected on different LGs. Four QTLs were identified for total length and body weight on Efu_LG8, 10, 13 and 19 on the tiger grouper map, which explained 6.6%–12.0% of the phenotypic variance. An epistatic QTL with a reciprocal association was observed between Efu_LG8 and 10. Two QTLs were identified for body weight on Ela_LG3 and 10 on the giant grouper map, which explained 6.9% of the phenotypic variance. Two‐way analysis of variance indicated that the QTL on Efu_LG13 interacts with the QTLs on Ela_LG3 and 10 with large effects on body weight. Furthermore, these six QTLs showed different features among the winter, summer and rainy seasons, suggesting that environmental factors and fish age affected these QTLs. These findings will be useful to understand the genetic structure of growth and conduct genetic breeding in grouper species.  相似文献   

2.
Interspecies hybridization is widely used in aquaculture as a beneficial strategy. Diploid and triploid hybrids have been detected from the interspecies hybridization of Epinephelus coioides ♀ × Epinephelus lanceolatus ♂. This is the first report of triploidization through hybridization in grouper. Confirmation has been obtained through flow cytometry, karyotyping and erythrocyte nuclei measurement. The chromosome numbers of E. coioides, E. lanceolatus, diploid hybrid grouper are 48 and triploid hybrid grouper are 72. Measurements of erythrocyte nuclei indicate that triploid fish have a larger nuclear surface than the diploid groupers, and the average ratio of triploid to diploid surface area is 1.59. During the first 1.5 years, triploid hybrid groupers grow faster than diploid hybrid groupers or either parent species. The average growth rate of triploid hybrids is 1.61 times greater than that of diploid hybrids at 6 months of age and 1.43 times greater at 18 months of age. The triploid hybrid groupers are inferior in gonadal development, with no primary‐growth‐stage oocytes appearing in the gonads at 18 months of age. Morphological studies indicate that triploid hybrid groupers have distinctive differences in snout length, eye diameter, body trunk shape, and tail shape development compared with diploid hybrid groupers. Triploid hybrid groupers have an advantage in growth ability, and artificial breeding of triploid groupers might be of great potential use in the grouper aquaculture industry.  相似文献   

3.
A six‐week growth trial was conducted to evaluate the optimum dietary isoleucine requirement of juvenile hybrid grouper (Epinephelus fuscoguttatus ♀ × Epinephelus lanceolatus ♂). Seven isoenergetic (3,400 kcal/kg of dry matter), isoproteic (496 g/kg of dry matter) and isolipidic (70 g/kg of dry matter) diets were formulated to contain graded Ile levels (7.3, 11.3, 15.7, 19.6, 23.5, 26.8 and 30.8 g/kg, dry‐matter basis). Each experimental diet was fed to triplicate groups of 12 hybrid grouper juveniles (average initial body weight: 6.00 ± 0.01 g/fish). Experimental fish were randomly distributed into 21 glass tanks (L 60 × W 45 × H 50 cm) connected to mechanical and biological water filters as a recycling system. Fish were fed twice daily (08:00 and 16:00) to apparent satiation. After the sampling of the growth trial, the remaining fish in each group were fed their corresponding diets for 2 d and then exposed to 4 mg Cu2+ · L?1 water for 24 hr. Results showed that growth performance and feed utilization were significantly affected by different dietary Ile levels (p < .05). Weight gain percentage (WG%), protein productive value (PPV), protein efficiency ratio (PER) and feed efficiency (FE) were increased as dietary Ile level increased, reaching a peak value at 19.6 g/kg dietary Ile, and thereafter, these four parameters declined as dietary Ile level continued to increase. Daily feed intake (DFI) showed an opposite tendency of variations as FE. The quadratic regression analysis of WG%, PPV, PER and FE against dietary Ile levels indicated that the optimum dietary Ile requirement for hybrid grouper was estimated to be 19.8, 20.8, 19.4 and 19.1 g/kg dry matter, respectively. Among all experimental treatments, fish fed 19.6 g/kg dietary Ile had the highest expression of growth and protein synthesis‐related genes, including growth hormone (GH) in pituitary, insulin‐like growth factor 1 (IGF‐1), growth hormone receptor 1 (GHR1), target of rapamycin (TOR) and S6‐kinase 1 (S6K1) in liver. Gut micromorphology was significantly influenced by dietary Ile levels. After the exposure to 4 mg Cu2+ · L?1 water for 24 hr, fish fed 19.6 g/kg dietary Ile had the highest survival and the best immunologic manifestation among all experimental treatments. Generally, the optimum dietary Ile requirement for maximum growth of hybrid grouper was estimated to be 19.8 g/kg dry matter, corresponding to 39.9 g/kg dietary protein.  相似文献   

4.
An 8‐week feeding trial was conducted to determine the requirement of protein for large‐size grouper Epinephelus coioides (initial body weight: 275.07 ± 1.56 g). Six iso‐lipidic (124 g/kg) diets were formulated containing graded levels of protein (350, 400, 450, 500, 550 and 600 g/kg). Grouper was hand‐fed twice daily to apparent satiation with triplicate. The results showed that significantly high weight gain, specific growth rate and significantly low feed conversion ratio were observed in fish fed 450 g/kg protein group. High‐protein level diets significantly increased protein content and significantly decreased lipid content of fish body and muscle. Total protein and cholesterol content in serum of 600 g/kg group were significantly higher than those of 350 g/kg group. However, serum glucose and triglyceride contents of fish fed low‐protein diets were significantly higher than those of fish fed high‐protein diets. Meanwhile, liver glutamic‐pyruvic transaminase and glutamic‐oxaloacetic transaminase in high‐protein diet groups were significantly higher than those of low‐protein diet groups. The intestinal protease activity in high‐protein diet groups was significantly higher that of low‐protein diet groups, but lipase and amylase showed opposite trend. With the increasing of dietary protein level, the activities of alkaline phosphatase, superoxide dismutase and lysozyme in liver of grouper increased significantly compared with 350 g/kg group, while the activities of acid phosphatase decreased significantly. With specific growth rate as the evaluation index, the optimum dietary protein level of large‐size grouper Epinephelus coioides was 438.39 g/kg by fitting the broken‐line regression analysis.  相似文献   

5.
The hybrid grouper, Epinephelus fuscoguttatus (♀) × Epinephelus lanceolatus (♂), is a newly bred cultivated marine fish species of high economic value. However, a skin ulcer disease with high mortality has occurred, and the responsible pathogen remains unknown. In this study, we summarized the epidemic status and external signs of this disease. We screened potential pathogens and finally isolated one bacterial strain ML01 from affected fish. We subjected healthy juvenile hybrid groupers to bacterial challenge tests with the isolate by immersion, immersion after dermal abrasion and intraperitoneal injection, respectively. Within 14 days post‐infection, the isolate ML01 caused mass mortality of juveniles infected via immersion after dermal abrasion or intraperitoneal injection. Diseased juveniles displayed obvious signs of skin ulcers. The median lethal dose of ML01 by intraperitoneal injection was 1.10 × 105 colony‐forming units. ML01 was identified as Vibrio harveyi by bacterial morphology, analytical profile index identification, 16S rDNA sequencing and multilocus sequence analysis. Antibiotic susceptibility tests showed that ML01 was sensitive to ceftriaxone, doxycycline and minocycline. The results of this study suggest that V. harveyi is the causal agent of skin ulcer disease in juvenile hybrid groupers, thus providing a basis for effective control and prevention of this disease.  相似文献   

6.
Since 2007, 96 wild Queensland groupers, Epinephelus lanceolatus, (Bloch), have been found dead in NE Australia. In some cases, Streptococcus agalactiae (Group B Streptococcus, GBS) was isolated. At present, a GBS isolate from a wild grouper case was employed in experimental challenge trials in hatchery‐reared Queensland grouper by different routes of exposure. Injection resulted in rapid development of clinical signs including bilateral exophthalmia, hyperaemic skin or fins and abnormal swimming. Death occurred in, and GBS was re‐isolated from, 98% fish injected and was detected by PCR in brain, head kidney and spleen from all fish, regardless of challenge dose. Challenge by immersion resulted in lower morbidity with a clear dose response. Whilst infection was established via oral challenge by admixture with feed, no mortality occurred. Histology showed pathology consistent with GBS infection in organs examined from all injected fish, from fish challenged with medium and high doses by immersion, and from high‐dose oral challenge. These experimental challenges demonstrated that GBS isolated from wild Queensland grouper reproduced disease in experimentally challenged fish and resulted in pathology that was consistent with that seen in wild Queensland grouper infected with S. agalactiae.  相似文献   

7.
Hybrid grouper juveniles (body weight, 6.1 ± 0.7 g) (brown‐marbled grouper, Epinephelus fuscoguttatus × giant grouper, E. lanceolatus) were fed with six isoproteic (50% crude protein) and isolipidic (12% crude lipid) feeds containing different levels of soy protein concentrate (SPC) in replacement of fish meal (SPC at 20%, 30%, 40%, 50% and 60% protein) and control feed (SPC0) for 6 weeks. Hybrid grouper juveniles were cultured in 100‐L fibreglass tank equipped with flow‐through water system and fed twice a day to apparent satiation level. The highest and lowest growth was recorded in fish fed SPC20 and SPC60 respectively. However, growth of SPC20 was not significantly higher than those fed SPC0, SPC30, SPC40 and SPC50 (p > .05). A decreasing growth trend was observed with the increasing level of SPC from feed SPC40 to SPC60. A noticeable better feed utilization was also observed in fish fed SPC0, SPC20, SPC30, SPC40 and SPC50 compared to fish fed SPC60 (p < .05). The fish condition factor, hepatosomatic index, viscerosomatic index and whole body proximate content of the fish were not affected by the graded levels of SPC. However, the body lipid content was significantly lower in fish fed SPC40 to SPC60 (p < .05). The apparent digestibility coefficient (ADC) of protein and lipid was significantly higher in fish fed SPC0 and SPC20 compared to other dietary treatments (p < .05). Based on the regression analysis on specific growth rate, the study suggests that the hybrid grouper grow best at 21.4% and can utilize up to 50% inclusion level of SPC in protein without significantly affect their growth and its body condition.  相似文献   

8.
The present study was conducted to investigate the protein requirement of grouper Epinephelus coioides at grow‐out stage (initial weight of 102.8 ± 1.02 g). Six iso‐lipidic diets were formulated using white fish meal and casein as protein sources with graded levels of protein (350, 400, 450, 500, 550 and 600 g/kg). Grouper was hand‐fed twice daily to apparent satiation in triplicates for 8 weeks. The results showed that lack of protein will lead to the declined of weight gain and specific growth rate and suitable protein not only improved growth, but also reduced feed coefficient rate. In addition, high‐protein level diet significantly decreased the morphological index of grouper. For the body proximate composition analysis, the high‐protein diets (500, 550, 600 g/kg) significantly increased the protein contents in the whole body and muscle which was contrary to as observed for the lipid content. High‐protein diets significantly improved the total protein levels of plasma which were contrast to as observed in triglyceride contents. Moreso, the cholesterol content was observed to be significantly decreased after high‐protein diet supplementation. The intestinal protease activity was observed to increase significantly with increasing protein supplementation whereas a decreasing trend was observed for the lipase and amylase activity with the highest going for the groups fed diets containing 350 g/kg protein as compared to the others. The liver alkaline phosphatase, superoxide dismutase and lysozyme activity increased with increasing protein level which later decreased. On the other hand, the acid phosphatase activity showed a significant downward trend. Based on SGR, the broken‐line regression analysis showed that the optimum dietary protein level and digestible protein level of the grouper Epinephelus coioides at grow‐out stage were 466.65 and 395.79 g/kg, respectively.  相似文献   

9.
Effects of rhythmic temperature change on the growth, body composition and energy budget of hybrid grouper (Epinephelus lanceolatus ♂ × E. fuscoguttatus ♀) were investigated. Nine groups of fish received repeating cycles of low‐temperature manipulation (22°C) for 1, 2 and 4 days followed by recovery temperature (28°C) for (3, 7 and 11 days), (6, 14 and 22 days) and (12, 28 and 44 days) respectively, designated as L1R3, L1R7, L1R11, L2R6, L2R14, L2R22, L4R12, L4R28 and L4R44 respectively. In the control group (C), fish were reared at 28°C throughout the whole experiment. After 96‐day feeding trail, the final weight, relative weight gain rate, specific growth rate, food conversion efficiency and apparent digestibility coefficient of fish in L4R28 were significantly higher than those of control (p < .05). The crude protein contents of fish in L2R14, L2R22, L4R12, L4R28 and L4R44 were significantly higher compared to the control (p < .05). According to energy budget, fish in L4R28 exhibited significantly higher proportion of food energy assimilated into growth and lower proportion consumed for excretion than the control fish (p < .05). These results indicated the occurrence of complete or over growth compensation in hybrid grouper, and the use of repeated cycles of low temperature (22°C) for 4 days followed by recovery temperature (28°C) for 28 days could obtain enhanced growth, that is overcompensation, with improved apparent digestibility coefficient, food conversion efficiency and energetic efficiency into growth. This technique would be more practically applicable in indoor culture for this species.  相似文献   

10.
Effects of Bacillus cereus BC‐01, Lactobacillus acidophilus LAG01, Clostridium butyricum CBG01 and their combinations as supplementation on the growth performance, digestive enzyme activities and serum non‐specific immunity of hybrid grouper (Epinephelus lanceolatus ♂×E. fuscoguttatus ♀) were assessed. Seven different diets, that is one control diet (basal feed without any probiotics, CT) and six treatment diets containing single B. cereus (Bs), L. acidophilus (Ls) and C. butyricum (Cs) at 1.0 × 109 cfu/kg feed, and also their combinations in equal proportion at 1.0, 2.0 and 3.0 × 109 cfu/kg feed (BLC1, BLC2 and BLC3) were prepared respectively. After 60‐day feeding trial, the final weight, specific growth rate,food consumption, food conversion efficiency and apparent digestibility coefficient of fish in Ls and BLC3 were significantly higher compared with the control (p < .05). The activities of pepsin and trypsin in the intestine of fish for Ls and BLC3 were significantly higher relative to the control (p < .05). Relative to controls, significantly enhanced amylase and lipase activities in proximal intestine except for Cs and BLC1 and lipase activities in distal intestine except for Cs were observed (p < .05). Meanwhile, activities of superoxide dismutase in the serum of fish for all treatments, lysozyme and catalase in Ls and BLC3, and glutathione peroxidase except for Cs were significantly enhanced (p < .05). Based on the above, dietary supplementation of single L. acidophilus at 1.0 × 109 cfu/kg or combination of three strains at 3.0 × 109 cfu/kg for hybrid grouper is recommended.  相似文献   

11.
Hybridization was used to take advantage of desirable traits in offspring. In the present study, we applied the cryopreserved Epinephelus lanceolatus sperm into interspecific hybridization with E. moara. Successful hybridization between these two species was achieved and cultured in 23–24°C seawater (34‰). There was no difference in survival rate between hybrid (E. moara ♀ × E. lanceolatus ♂) and non‐hybrid (E. moara ♀ × E. moara ♂) at 24 hrs post hatch (HPH), but less hybrid (14.35 ± 8.02%) hatched than non‐hybrid (93.60 ± 1.65%), which might be due to irregularity cell cleavage and skeletal deformities from the formation of embryonic body to the later embryonic development. Similar phenomenon was found in hybrid embryos from fertilization with fresh sperm, indicating that species variations between parents, rather than cryopreserved sperm, resulted in deformities in embryos. Mean hatch time of the hybrid was 1 hr faster than that of E. moara. The hybrid was 1.95 ± 0.06 mm in total length when newly hatched and reached 38.00 mm at 58 days post hatch (DPH), which showed faster growth than E. moara (recorded in the previous study). Considering its faster growth, E. moara × E. lanceolatus hybrid was a potential breeding production in aquaculture. Over 212,000,000 larvae have been produced and launched in the market since 2015. The results of this study also shed some lights on further comparative studies in grouper hybrid performance.  相似文献   

12.
The potential of Bacillus subtilis E20‐fermented soybean meal (FSBM) as a partial alternative component of fish meal (FM) in fed diets of orange‐spotted grouper (Epinephelus coioides) was evaluated in this study. An FM‐based diet and seven diets containing 10%, 20% and 30% and 10%, 20%, 30% and 40% of FM replaced by soybean meal (SBM) and FSBM, respectively, were fed to grouper for 84 days to evaluate possible substitution levels of FM by tracking growth performance, digestive enzyme activity and morphological changes in the liver and distal intestine. No significant differences in survival and muscle composition of grouper were found between controls and treatments. Growth performance and feed efficiency of fish fed diets with FM replaced by FSBM up to 30% were not significantly different from controls, whereas significantly decreased growth performance and feed efficiency occurred with diets containing >20% of SBM. Based on the feed efficiency, the maximum substituted levels of FM by SBM and FSBM in grouper diets were 18.36% and 29.32%, respectively, based on broken‐line analyses. Histopathological changes in the liver and distal intestine, and significantly lower activity levels of digestive enzymes, including pepsin in the stomach and trypsin, chymotrypsin, amylase and lipase in the distal intestine, were found in fish fed a diet containing 30% of FM replaced by SBM. However, these parameters were improved by the substitution of FSBM. It is therefore believed that FSBM has great potential to be used as a protein source in grouper diets in partial replacement of FM.  相似文献   

13.
Scale drop and muscle necrosis disease with high mortality widely occurred recently in the hybrid grouper (Epinephelus fuscoguttatus ♀ × E. lanceolatus ♂), a crucial cultured marine fish species in China. In this study, 30 Harveyi clade isolates of 27 Vibrio harveyi strains were isolated from diseased hybrid groupers in the south‐east and north‐east coastal areas of China. A total of 22 V. harveyi strains were determined to be pathogenic, and most challenged fish died within 2 days of infection; surviving individuals exhibited scale drop and deep dermal lesions as naturally diseased fish. Although five typical virulence genes, including luxR, toxRVh, chiA, serine protease and vhh widely existed in V. harveyi, no obvious correlation was established between virulent strains and virulence genes harboured in them. Furthermore, multiple antibiotic resistance was widely exhibited in Harveyi clade strains, particularly for penicillins, polypeptides, lincomycins, acetylspiramycin, streptomycin, metronidazole and bacitracin. And the multiple antibiotic resistance indices were gradually decreased from southern to northern areas of China. This study demonstrated that the pathogenic V. harveyi with multiple antibiotic resistance is highly prevalent in hybrid grouper in China, which requires particular attention.  相似文献   

14.
The study evaluated effects of cholesterol supplementation in a diet with high soybean meal (SBM) on the growth and cholesterol metabolism of giant grouper (Epinephelus lanceolatus). All‐fish‐meal diet was used as control. The diet including SBM (replaced 50% of the fish meal protein, SBM diet) and the SBM diet supplemented with 10 g/kg cholesterol (SBM + cholesterol) were used as experimental diets. Three diets were each fed to triplicate groups of juvenile grouper (initial body weight: 12.39 ± 0.36 g) in a recirculating aquaculture system for 8 weeks. Grouper fed the control diet showed higher (p < .05) weight gain, feed intake, feed efficiency and protein efficiency ratio than the other two dietary treatments. Hepatic cholesterol concentrations and 3‐hydroxy‐3‐methylglutaryl coenzyme A reductase gene expressions were higher in fish fed the control diet than fish fed the control diet and SBM + cholesterol diet. Hepatic cholesterol 7α‐hydroxylase gene expression was higher in fish fed the SBM + cholesterol diet than that in fish fed the control diet. Results indicate that giant grouper on a diet low in cholesterol can regulate cholesterol synthesis, suggesting that the reduced dietary cholesterol intake in the fish fed diet containing SBM is sufficiently compensated by increased cholesterol synthesis.  相似文献   

15.
A 10‐week feeding experiment was conducted to evaluate the effects of replacing fish meal with soybean meal (SBM), with or without dietary arginine (Arg), on growth performance, immune indices and intestinal morphology of grouper, Epinephelus malabaricus. Nine experimental diets were formulated to contain 20%, 30% and 40% fish meal protein (FMP) replaced using SBM and 0, 0.5% and 1% dietary Arg supplementation. The results showed that weight gain (WG) of fish was significantly affected by the interaction of substitution level and Arg supplemental level. The maximum WG occurred at the 30% FMP substitution level and the 0.5% Arg supplemental level. The immune assay showed that the interaction between the two levels significantly influenced the production of serum nitric oxide but did not affect serum IgG concentration and alkaline phosphatase activity or the liver IGF‐1 gene expression. Significant interaction effects between the two levels were observed in muscle layer thickness (tML) and fold height (hF) in the proximal and mid‐intestine. High SBM level in diets reduced the tML and hF in the entire intestine. The results suggested that the interaction of 30% FMP substitution level and Arg supplemental level of 0.5% most benefitted growth performance, immune indices and intestinal structure of grouper.  相似文献   

16.
The link between quorum sensing in Vibrio campbellii and its virulence towards tiger grouper (Epinephelus fuscoguttatus) was investigated using V. campbellii wild type and quorum‐sensing mutants with inactive quorum sensing or constitutively maximal quorum‐sensing activity, and signal molecule synthase mutants. The results showed that wild‐type V. campbellii is pathogenic to grouper larvae, causing more than 50% mortality after 4 days of challenge. Furthermore, the mortality of larvae challenged with the mutant with maximally active quorum sensing was significantly higher than that of larvae challenged with the wild type, whereas a higher survival was observed in the larvae challenged to the mutant with a completely inactive quorum‐sensing system. Grouper larvae challenged with either the signal molecule synthase triple mutant, the harveyi autoinducer‐1 (HAI‐1) synthase mutant and the autoinducer‐2 (AI‐2) synthase mutant showed higher survival than larvae challenged with the wild type. In contrast, larvae challenged with the cholerae autoinducer‐1 (CAI‐1) synthase mutant showed high mortality. This indicates that HAI‐1 and AI‐2, but not CAI‐1, are required for full virulence of V. campbellii towards grouper larvae. Our data suggest that quorum‐sensing inhibition could be an effective strategy to control V. campbellii infections in tiger grouper.  相似文献   

17.
A 50‐day feeding trial was conducted for juvenile pearl gentian grouper (Epinephelus lanceolatus ♂ × Epinephelus fuscoguttatus ♀) to determine the optimal amount of Tenebrio molitor meal (TM) that could replace fishmeal (FM) in feeds without reducing growth performance, antioxidant enzyme activities and resistance. Six isonitrogenous and isolipidic diets were formulated with TM replacing 0% (T0), 6.25% (T6), 12.5% (T12), 18.75% (T18), 25% (T25), 31.25% (T31) FM respectively. Each diet was randomly divided into triplicate groups with 30 juveniles (initial weight 6.60 ± 0.00 g). After feeding trail, fish were challenged by Vibrio harveyi for 7 days. The results showed that each treatment had better survival rate between 96.67% and 100%. Fish fed with control and T6 diet showed lower final weight and weight gain rate as compared to other diets. The feed conversion ratio of fish fed on T12 and T18 diet had no significant difference compared to control diet. As compared to control diet, other diets had no significant differences on specific growth rate and temperature growth coefficient. Fish fed with T6 diet had highest liver glutathione reductase activities. No significant differences were observed in liver superoxide dismutase activities in fish fed with T6, T12, T25, T31 and control diet. Fish fed on T18 diet had lowest hepatic malondialdehyde contents and a highest relative per cent survival. According to a broken‐line model, the recommended substituted ratio of TM for FM was estimated to be 12.3% for grouper obtaining maximum WGR, corresponding to additive amount of TM is 4.92%.  相似文献   

18.
An 8‐week feeding trial was conducted to estimate the optimum dietary manganese (Mn) requirement for juvenile hybrid grouper, Epinephelus lanceolatus × E. fuscoguttatus. The basal diet was formulated to contain 520 g/kg crude protein from casein and fishmeal. Manganese methionine was added to the basal diet at 0 (control group), 2.5, 5, 10, 20 and 40 mg Mn/kg diet providing 7.48, 10.34, 13.76, 19.72, 31.00 and 53.91 mg Mn/kg diet, respectively. Each diet was randomly fed to triplicate groups of juveniles, and each tank was stocked with 20 fish (initial weight, 60.06 ± 0.68 g). The manganese content in rearing water was monitored and kept below 0.01 mg/L. Results showed that the weight gain ratio (WGR), protein efficiency ratio (PER), specific growth rate (SGR), Mn contents in whole body, liver and vertebra, and activities of hepatic Mn superoxide dismutase (Mn‐SOD), total SOD (T‐SOD) and glutathione peroxidase (GSH‐PX) were significantly improved by dietary Mn supplementation (p < .05). However, dietary Mn did not affect arginase (DArg) activity. The highest feed conversion ratio (FCR) was observed in fish fed the basal diet (p < .05). No significant differences were found on the Cu and Zn contents in whole body by supplementing dietary Mn. Supplemented Mn in diets had significantly effect on liver and vertebral trace element deposition (p < .05). Fish fed the basal diet had the highest Fe and Zn contents in vertebra (p < .05). There were no significant differences on hepatic pyruvate decarboxylase (PDC) activity with supplemented Mn levels below 13.76 mg/kg. As biomarker of oxidative stress, malondialdehyde (MDA) content in liver was significantly higher in fish fed the basal diet (p < .05). Using the broken‐line models based on SGR, dietary Mn requirement of the juvenile hybrid grouper was estimated to be 12.70 mg/kg diet.  相似文献   

19.
In the present study, reported was an unidentified trypanosome that caused massive mortalities of cultured humpback grouper, Cromileptes altivelis (Valenciennes, 1828) and brown‐marbled grouper, Epinephelus fuscoguttatus (Forsskål, 1775) in the net‐cages in Sanya, China, and some general pathological features of E. fuscoguttatus after experimental infection of the trypanosome. Before dying in the net cages of diseased fish, listlessness and anorexia were the observable symptoms. The blood of the diseased fish was light‐coloured in comparison with that of healthy one. E. fuscoguttatus experimentally infected with this trypanosome are with different degrees of engorgement in gill lamella, liver, spleen and kidney. Tissue lesion and necrosis were observed in liver and spleen of diseased fish.  相似文献   

20.
During culture of grouper, cannibalism is a frequent phenomenon that usually causes economic loss. Grouper culture often requires grading to prevent size‐dependent cannibalism. In comparison with orange‐spotted (Epinephelus coioides) and giant grouper (E. lanceolatus), failure to swallow prey during cannibalism is frequently observed in brown‐marbled grouper (E. fuscoguttatus). The cannibal cannot engulf the entire prey and the two fish ultimately end up dying together. Herein, we attempted to compare morphometric differences among orange‐spotted, giant and brown‐marbled grouper. We established a cannibal–prey total length (TL) relationship for brown‐marbled grouper: TLprey=0.71 TLcannibal−1.75. According to the equation, a difference of approximately 50% in TL is a threshold to use for grading the grouper. This value is much larger than that used (30%) in orange‐spotted and giant grouper, and this size difference results in a higher incidence of failed cannibalism attempts in brown‐marbled grouper. It is our belief that the standard grading method will fail to produce as good an effect in brown‐marbled grouper as is seen in orange‐spotted and giant grouper. Therefore, in addition to grading, other manipulations such as satiation feeding, nutritional supplementation and optimal stocking densities should be applied to reduce cannibalism of brown‐marbled grouper.  相似文献   

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